Tips for Minimizing Warp in HPL Panels 1 SIDES HPL (Not two sides)

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All panel components should be acclimated to the same environment prior to assembly. This will ensure that one component will not be contracting while the other is expanding due to subsequent relative humidity changes. In addition, under extreme conditions, materials that have not been properly acclimated to the same condition prior to fabrication can buckle or de-laminate, as well as warp. Proper preconditioning of materials can also help to minimize shrink-back or laminate growth problems on machined edges.

For critical applications requiring a well-balanced assembly (doors, etc.), the same laminate should be applied on both sides. Less critical applications may only require a cabinet liner or phenolic backer.

Thick panels warp less than thin panels due to increased rigidity and the geometry of the forces involved. For critical applications, the thickest core material permissible should be selected to help minimize warpage.

Laminates expand and contract twice as much in their crossgrain direction as they do in their grain (parallel with the sanding lines) direction. Always align the sanding lines of the front and back laminates in the same direction and, wherever possible, align the grain direction of the laminate with the longest panel dimension. It is also advisable to align the grain and cross-grain directions of the laminates with that of the substrate. Note: When multiple panels are viewed together, keep all laminate components aligned in the same direction to minimize visual changes in color or gloss due to the directionality of the underlying surface paper and laminate finish.

Use the same adhesive and application techniques (application rate, method of application, drying techniques, etc.) for bonding the front and back laminates. This is especially important when using water-based adhesives such as PVA (white glue), ureas or water-based contacts which introduce additional moisture into the panel assembly. In addition, if panels are being hot pressed, the top and bottom platen temperatures may require temperature adjustments to produce flat panels. Temperatures used to effect glue line cure can cause shrinkage of the glue and surfacing materials. Generally, the side having the thicker skin will require a slightly higher platen temperature than the side having a thinner skin (cabinet liner, phenolic backer, etc.), due to heat transfer rates. Bottom platen temperature may also require reduction to compensate for the additional contact time involved while the press is being closed and opened.

Moisture barriers such as paint, varnish, vinyl film, and other coverings including impregnated fiber backers will not balance a panel having a laminate on the other side. Coatings or materials of this type do not exhibit the same strength or dimensional change characteristics as a laminate. Remember, the strength and expansion/contraction rates of the face and back skins must be matched for proper balancing.

Installed laminate-clad panels will expand and contract with humidity changes. Provide sufficient spacing between panels to allow for this. Panels or countertops that are locked between two walls or other such restraints should have a sufficient gap allowed to accommodate dimensional movement. Wider panels and higher humidity swings require more spacing. A general rule of thumb is to allow 1/8″ (3.18mm) minimum between panels having widths of 48″ (121.9cm).


  • Acclimate or precondition materials.
  • Use same laminate on both sides unless panel is small or mechanically restrained.
  • Thick core resists warpage better than thin core.
  • Align sanding marks on both sides.
  • Use the same adhesive and application techniques on both sides.
  • Paint, varnish, vinyl film and fiber backers will not balance high pressure laminates.
  • Spacing is required between panels to allow for movement.


Laminate-clad panels are susceptible to warpage if they are not physically restrained or balanced. Balanced panel construction equalizes the forces acting on both sides of the core material. If for any reason these forces become unbalanced, warpage can result. Warpage of wood product panel assemblies (e.g., laminate-clad particleboard or MDF ) is attributed to the differences in dimensional movement between the face and back laminates and the core or substrate material. This movement and its subsequent stresses are caused by the expansion or contraction of paper fibers in the laminate skins and wood fibers in wood composite cores as they respond to relative humidity changes. The stress and dimensional movement generated within a laminate skin are transmitted to the core through its glue line. The forces involved are tremendous and, if they are not properly considered in the panel design, warpage can result. The use of laminates and substrates that have different strengths and/or dimensional movement potentials is not the only cause of warpage. Exposing one side of a panel assembly to different humidity conditions than the other side can also cause warpage. For example, a “balanced” panel will warp if one side is exposed to air conditioning and the other is against a damp, below-grade wall (e.g., basement wall without a proper moisture barrier).

Other tips about the HPL 1SIDE WARPPING PROBLEM

Warp is defined as the “deviation of the geometry of a panel from an initial state of flatness.” This document outlines some factors (balanced construction; material handling and storage; and proper laminating, fabricating, and installation techniques) that affect warp, and steps a laminator or fabricator can take to minimize it.

Balanced Construction One of the most common causes of warp in laminated panel products is unbalanced panel construction. As different materials are rigidly bonded together, moisture content changes may occur. In response to the changes in moisture content, the materials attempt to change dimensions. When that happens, stresses can accumulate. Warp results when these stresses become excessive and are no longer balanced on the two surfaces. This imbalance may be caused by a number of factors, including selection of laminate, laminating environment, component conditioning, product design, installation, and application. Selection of laminates and balanced construction go hand-in-hand. The laminates and/or coatings applied to each side of a PB or MDF substrate should be similar in properties. Generally, this is best achieved by using the same material to cover both sides of a substrate.

Unusually moist or dry conditions should be avoided in the laminating and storage environments. The moisture content of wood-based materials and laminates is dependent on the amount of moisture in the air. When these materials are moved from one environment to another, the moisture content changes. Resulting dimensional changes can be substantial. Once assembled, differences in the expansion or shrinkage characteristics of the laminate and substrate can produce stresses which cause warped panels. Ideally, laminates and substrates should be stored and assembled in conditions similar to the finished product application environment. It is unlikely that the moisture content of the laminate and the substrate will be in equilibrium with the laminating environment when they are delivered. Allow sufficient time for the laminate and the substrate to adapt to the laminating environment. It can take two or more weeks to reach a satisfactory equilibrium. Seasonal changes and air circulation around the materials will influence the time it takes. Laminates at one equilibrium moisture content (EMC) condition should not be applied to PB/MDF of a different EMC condition. If they are, as the moisture content equalizes, the PB/MDF substrate may expand or contract while the laminate seeks the opposite. When bonded with rigid adhesives, the components cannot move in relation to each other. This creates stresses at the substrate/laminate interface which can result in a warped panel.

An imbalance in moisture-related expansion or contraction frequently causes warping of laminated panels. Such an imbalance is activated by changes in moisture content. A change might be temporary, as in the case of wetting one side of a flat panel. The resulting “transient warping” is beyond the c o n t r o l o f t h e l am i n a t e d – p a n e l manufacturer. In theory, “structural warp” resulting from a built-in imbalance can sometimes be prevented. Balanced lamination is the key to consistently manufacturing flat panels. The natural variability of the laminate and substrate properties is a common cause of warping, particularly in the case of a thin substrate with relatively thick laminate faces. Controlling the variability between the laminates can effectively reduce warp in laminated panels. The concept of balance does not end with the manufacture of a balanced panel. The installation and the end-use environments can also be sources of moisture imbalance that create internal stresses resulting in warp. To ensure acceptable laminated product performance, design and engineering must consider the product application and environment.






Water-Based Glue, Lamination, and Warping

Using water-based adhesives for laminating to wood-fiber panels can cause the panels to warp. To prevent, laminate both sides. May 20, 2006

We are having a problem in lamination when we laminate HPL onto MDF using PVA glue. It tends to warp on the other side of the lamination. Does anyone have any suggestions?

Forum Responses
(Adhesive Forum)
From contributor L:
You need to put the same HPL on both sides to prevent the warping.

From contributor R:
Inexpensive backer material is available for this. Have you tried looking into contact cement instead of PVA?

From contributor M:
PVA glue is water-based and expands the surface as it is spread on causing the board to warp. Solvent based contact cement has no water and will not do this. However, if you put no laminate on the bottom surface, that naked surface will eventually soak up or shed humidity and cause the panel to warp anyway.

From contributor C:
When using any water-borne adhesive to laminate only one side of a panel, warping will always occur to some degree due to the fact that the core expands when it absorbs water from the adhesive. This is particularly true of MDF. After the panel is removed from the press the core is still expanded due to the remaining water trapped in the wood fibre. At this point I’ve seen the panel warp away from the HPL due to expansion of the surface the adhesive was applied to.If you’re lucky, when the water eventually dries out, the core will shrink back to its original dimensions and the panel will be flat again. If the panel actually over-dries or if the backside picks up moisture later on (manufactured under low humidity but installed into humid conditions) then the panel may warp forward or towards the HPL surface. Using a very high solids PVA (65%+) may help somewhat. However the preferred solution is to use an inexpensive HPL “backer” sheet and laminate both sides of the panel to balance the forces which would otherwise cause the panel to warp. This is the method specified by the Architectural Woodworking Institute for it members when doing laminated panel construction for architectural millwork.





Balanced Laminating Over Melamine

Here’s a detailed discussion about whether it’s okay to apply laminate over just one face of a melamine door, and about various other ways to achieve the same product. October 12, 2012

Every time I talk to my plastic lamination outsource vendor, he gives me shit about how I make Formica laminated commercial cabinet doors. Instead of going through all the trouble of having him laminate plastic to one face of particleboard and white cabinet liner plastic to the other, I simply contact cement the plastic to one face of two-face melamine particleboard, trim, and edgeband. The result looks exactly the same as what the laminator gives me, and is considerably cheaper given that the white liner is omitted and the whole operation involves no press time.

He claims that this is not a balanced panel and will surely warp, but I have done this hundreds of times and never had a warp any worse that you can get with his “proper” method. Does anyone else do this?

Forum Responses
(Cabinetmaking Forum)
From contributor P:
My very first Formica kitchen was built the way you do your doors. The material back then was called Kortron. It had a shiny white baked-on finish on one side and plastic laminate applied with contact cement on the other. It warped, so I started balancing the panels. If your mileage varies it is only because you are lucky.

From contributor D:
Like you, we have been laminating over white melamine for years without a failure. However, for larger projects we will often purchase MDF door board that has a white liner on one side. It gives a little more peace of mind. We often use PVC edges so we lay up in sheets, cut and then band. If we are doing HPL edges, we band and then face.

From contributor C:
I’ll admit we have done the same in tight deadlines, but now I actually have 11/16 particleboard with a liner on one side and no laminate on the other. This allows us to lay up fast and in a balanced panel fashion. We have not had failures in the past, but it is not balanced.I studied the time to pull a sheet on melamine with paint grade on one side and melamine on the other, opening the box of p-lam and laying it up, trimming and then walking it to the saw, versus buying pre-laid up with a liner, set at the saw, and the conclusion is absolutely obscene. We expend waste of 30.00 in labor doing it ourselves rather having it done for us. On 40 sheets, that’s 1200! And on a job that size we cannot afford delamination, warped panels or the loss of time on the labor, when it can go to many other areas.

From contributor T:
I think that the bigger factor is that it is a lot cheaper to just buy the panels laminated. I can usually get them within a few days. And yes, balance the panels, or you will regret it.

From contributor L:
You are lucky! I’ve seen this fail several times and won’t do it in our shop. We buy pre-laminated panels as much as possible, almost always with laminate both sides. Cabinet liner is better than nothing, but still not truly balanced.Fact is, pre-lam is cheaper than doing it in house, and you get a better product because they use hard glue, not contact.

From contributor K:
I’m surprised nobody has mentioned that using contact cement does not cause unbalancing because it’s not a rigid glue. The questioner’s technique works fine and is not unbalanced. But contributor L’s point is correct. Post laminating melamine is still not cheaper than buying a pre-laminated panel with a cabinet liner back. What you save in material you more than lose in labor.

From the original questioner:
I have to say that it is just as cheap for me to cut up melamine into door sizes, cut up the Formica slightly oversized, contact cement the Formica on and trim, as it is for me to order laid up panels pre-cut to door sizes. (I have to order pre-cut since I cannot cut the laminated panels myself without a chippy saw kerf on one side or the other.) At this point, either way, the panels have to be edgebanded and there is no labor difference there.Maybe my laminator is ripping me off. But I am prone to think that there is just as much labor for him to spread glue on two sides of PB, stack the panels in his press, take them off his press and onto his beam saw to cut to size, and then strap all the pieces and send them out to me. And maybe I have always gotten away with this because I always use two face melamine (not paint grade back or one sided) and solvent based contact cement. I was always told that Formica laminate was developed to have the exact same coefficient of expansion-contraction as wood itself.

One final point: I have actually on occasion used my laminator for big door jobs, and I have experienced some warping even then.

From contributor C:
Yikes – so sanding the melamine does not take time? Apparently we are paying a different rate than you are. We use the paint grade or good one side so we don’t have to sand.

From contributor T:
The main reason that is cheaper is because they buy laminate at the wholesale price. Give West Coast Laminates a call.You have to balance the panel with the same thickness material on both sides. Instead of cabinet liner you have to use 949 of the same thickness as the face.

I doubt the comment about contact cement, as that has not been my experience. I mean if you just put a sheet of particleboard in the sun, it will warp because of the difference it causes in moisture content.

From contributor S:
I can’t even buy the sheet laminate as cheap as I can buy it already laid up. My price for a 4×8 sheet of Formica from my supplier is about $50-55. Two of those with a sheet of MDF will run me about $130 or so. Plus the cost of the contact cement and a roller. And the labor to lay it up. I can order a 2-sided 4×8 laid up Formica panel with 3/4 MDF core for $100. All I have to do is cut and edgeband. No contact cement.

From contributor L:
“Formica laminate was developed to have the exact same coefficient of expansion-contraction as wood itself.” Not true! For a start, laminate is directional. It moves more in one direction than the other. That’s why you always lay the laminate the same way front and back.We just ordered 20 .75 x 4×8 sheets to finish out a job. Lam one face, liner back (not ideal, but the customer specified). Price was $68. 3/4″ particleboard core, Wilson VG lam, white cab liner. I don’t see any way we could beat that price in our shop using contact cement. You guys must be a lot faster at laminating than our guys.

From contributor R:
We laminated to melamine for many years and rarely had a problem. However, melamine backed doors are not allowed under AWI Custom Grade, and almost all of our work is AWI specified. I know of a couple cabinetmakers who ended up replacing every door and drawer front in a large job because the architect insisted that they meet the spec. Silly or not, it happened, and I didn’t want to get caught that way, so I started making balanced panels. I also used the fact that our panels were balanced to distinguish us in yet another way from our competition.I made a relatively small investment in used panel layup technology, and found that we could make balanced panels less expensively than melamine backed panels. We went from 12-15 minutes per side spraying and laying contact to about 4 minutes for 2 sides. We buy white V Grade in bulk and core in bulk so we get good materials prices. The PVA glue we use is about a third the cost of contact. It’s also non-toxic, non-flammable and has no VOCs. The glue line is hard, not flexible like contact, so there is no shrinkage from side to side. We can do 150 panels in a shift and we often laminate for others. Among the other benefits of this system is that we moved to miter-folding most of our straight laminate countertops, so we lay up countertop blanks and have cut our counter assembly times in half. All in all, a very positive evolution.


What is HPL made of?

It consists of about 60-70% paper and about 30-40% thermosetting resins. The latter are of two different types; the inner layers of paper are impregnated with phenolic resin and the outer layers with melamine.

How is a sheet of high-pressure laminate made?

HPL laminates consist of superimposed layers of paper, impregnated with thermosetting resins and permanently bonded together by simultaneously applying heat (greater than 120° C) and pressure (greater than 5 MPa) for periods of 40 / 50 minutes.

Do the levels of heat and pressure the materials are subjected to in the presses affect the properties of the finished product? If so, how and to what extent?

The quality of HPL laminates is influenced by the levels of heat and pressure applied during manufacture. Arpa employs a pressure greater than 7 MPa and a temperature of about 150° C. The surface and structural qualities of the laminates achieve a high standard as a result.

What makes a low-quality HPL different from an excellent one?

Poor resistance to scratching, impact, wear, steam, heat, stains and light are indicative of poor quality raw materials and/or manufacturing processes employing lower pressures or temperatures and shorter heating times. The minimum performance requirements are set out in EN 438.


What temperatures can HPL withstand without deterioration or discoloration?

HPL can withstand up to 180° C without deterioration or discoloration. However, this relates to an accidental rather than a regular occurrence in that prolonged and localised heat can cause loss of brightness in the decor colour as well as yellowing and surface blistering. In the kitchen, care should be taken to avoid direct contact with saucepans just taken off the cooker; the bottom of a pan containing hot oil can reach 250° C.

In terms of resistance to heat, moisture, scratching, impact etc. does each type of HPL have specific properties?

Every HPL can claim exceptional hardness and resistance to scratching, impact, abrasion, chemicals and heat. Each type can have very different characteristics, however, in line with the required performance for the specific application. European standard EN 438 classifies HPL into different grades according to its properties and application: Standard (S); postforming (P); suitable for horizontal (H) or vertical (V) applications; flame retardant (F); compact (C) or external (E), pearlescent (A), metal (M) or wood veneer finishes (W), multicolour core (B) and metal reinforced. For example, laminates for horizontal applications have more resistant surfaces than those for vertical applications, the physical and mechanical properties of thick laminates are greater than those for thin ones, postforming laminates can be hot formed and flame retardant laminates have increased fire ratings.

What is meant by antibacterial HPL?

In general, all HPL is inherently hygienic due to the density of its surface and its ease of cleaning. ARPA’s SILVERLAM HPL has a special innovative structure providing anti-bacterial protection. This is microbiologically tested and uses silver ions to inhibit bacterial growth and reduce the quantity of bacteria by 99%.

What are the properties of HPL, in general?

Its main mechanical, physical and chemical characteristics are:
– Impact resistance
– Scratch resistance
– Lightfastness
– Ease of cleaning
– Heat resistance (occasional, up to 180°C))
– Hygiene
– Suitability for contact with food

Where there are special performance requirements for specific applications, can Arpa provide specific product details?

Yes. Where there are specific requirements, products with particular aesthetic or performance characteristics can be devised, as long as the design satisfies technical feasibility and environmental and economic sustainability criteria. It is important to note, however, that the existing Arpa collections already contain a wide range of attested products and applications. So, at first, it would be better to aim for a selection from the products in the catalogue; Arpa’s sales and technical departments are always available to customers and will be able to recommend the most suitable products for every situation.

Do laminates follow the CE marking rules for construction products?

Only laminates 2mm or more thick used in the construction industry (e.g. walls) must conform to the rules for CE marking. For all other applications, such as furniture, this specific marking is not required.

What international standards does HPL meet?

There are two international standards, both of a voluntary nature, European Standard EN 438 (European HPL regulations) and ISO 4586. These set out the minimum requirements and the performance characteristics for each type of HPL. EN 438 is the most complete and recent standard as it considers not only the more traditional types of laminate but also the more aesthetically and technically advanced varieties.

Can Arpa issue certificates or test report documents on request?

Some Arpa laminates have been certified for use in the construction, shipbuilding and railway industries. Arpa can guarantee that these products comply with the relevant rules and regulations. Customers should request this when ordering.

Which of the existing standards is commonly used?

The 2004 revision of international standard ISO 4586 in two parts, one dealing with the specifications and the second with test methods, takes a standpoint aimed at a global market but has now become obsolete. The European EN 438 standard is more up to date and has 9 parts. The first part is a guide while the second covers test methods. Parts 3, 4, 5, 6, 8 and 9 deal with the different applications. Part 7, which is mandatory as regards compliance with European Regulations for Construction Products, covers the requirements for CE marking.

Can different finishes affect the properties of the finished product?

Yes. For example, a glossy finish will be less scratch resistant than a more textured one. For more detailed information, it is always advisable to refer to the specific Product Data Sheet for each laminate.

What performance standards does EN 438 require?

EN 438 consists of 9 parts but only one of these sets requirements. Part 7, in fact, deals with the essential requirements specified in the terms of reference of the European Commission Regulations on construction products, M/121 (interior and exterior wall and ceiling finishes) and M/113 (wood based panels). Parts 3, 4, 5, 6, 8 and 9 of the EN 438 Standard each apply to specific types of laminate and give recommendations for areas of application, laminate performance standards and test methods. We recommend reading these parts carefully for detailed technical information.


Are there special certifications for the transport industry?

For transport, for example in the automotive and railway industries, European technical regulations exist but product approvals and/or certifications are currently handled by national agencies and are valid locally.

If a higher fire resistance is required (e.g. REI 240) what grade of HPL should I use?

The HPL laminate is only one of the materials that make up the finished product. It will be the manufacturer who needs to test the structure consisting of different materials and then choose which laminate to use. As a general rule, in this particular case, it may be advisable to use a flame retardant laminate.

As regards reaction to fire, are there classifications and test methods approved and accepted across Europe?

There is only a common reaction to fire classification for the whole of Europe with regard to products used in the construction industry. For all other sectors, each country has its own laws or regulations. For construction, the European Construction Products Regulations (CPR) apply, stipulating a series of health, safety and energy saving specifications. HPL laminates must also meet these requirements in order for the manufacturer to gain CE marking and market them throughout the European Community. There is also a technical standard for the railway industry, CEN TS 45545, which has not yet been approved as a harmonised standard however. In this context, therefore, local regulations still prevail.

As regards reaction to fire, to which Euroclass do Arpa’s flame retardant laminates belong …and what about the standard grade?

Arpa’s Flame Retardant HPL can achieve Euroclass B, that is the best performance possible for an organic material. The standard grade, however, conforms to the requirements of EuroclassD.

In construction, are there national regulations and markings as well as the European ones?

European regulations for construction products include a reaction to fire classification but each nation is free to adopt different minimum requirements according to the type of application. This means that based on assessments by local supervision agencies (e.g. Interior Ministries and Fire Brigades), different European classifications may be required for similar applications. In addition, public institutions and associations in each European country can establish national markings that have more stringent specifications for certain technical criteria. These are optional markings (because they would otherwise constitute an obstacle to the free movement of goods) that nevertheless become essential for the local market.

As regards reaction to fire, to which classification in the UK building regulations do Arpa’s flame retardant laminates belong …and what about the standard grade?

If bonded to a suitable fire-retardant substrate with the proper adhesive, Arpa’s flame retardant HPL fulfils the requirements of Class 1 and Class 0. Where class 1 or class 0 is required for the application, it is important to specify the rating for reaction to fire.

In construction, if there are national regulations and markings as well as the European ones, what is Arpa’s approach?

Arpa products are supplied with European certification. Customers should check the local requirements. In the case of national markings such as the French CSTBat or the Dutch Komo, Arpa conforms to the local market.

As regards reaction to fire, to which classification in American regulations do Arpa’s flame retardant laminates belong …and what about the standard grade?

One of the most important tests for the North American construction industry is the ASTM E 84 (Tunnel test). ARPA’s flame retardant Integrale laminates achieve class A, which is the highest, while the standard grade achieves class B.

How does the manufacture of Flame Retardant HPL differ from that of the standard grade?

Laminates are organic materials which, by their very nature, even in the standard grade, do not burn very well or rather, do not ignite easily when exposed to flames and contribute relatively little in the event of a full scale fire. There are also flame retardant HPL laminates which, unlike the standard ones, are manufactured with special additives that make them particularly flame resistant. They are used in the construction and transport industries where there are legal requirements or safety regulations. The additives are halogen free.

Are there special certifications for the shipbuilding industry?

Yes. In shipbuilding, there are the European MED regulations followed by shipyards for the construction or refurbishment of ships flying European flags.

For fire doors should I use flame retardant HPL or I can use the standard grade?

Fire resistance is the ability to retain load bearing capacity (R), integrity (E) and insulation (I) properties for a defined period of time. In the construction of buildings, this is assessed for finished elements with structural functions (e.g. doors or walls) in which the HPL laminates are just one component. For fire doors, it is essential to use a structure with the required REI properties such REI 30 or REI 60 (where the numbers indicate the minutes for which the element retains these properties). If the substrate possesses the correct fire resistance properties and the adhesive is suitable, it is also possible to use the standard grade of HPL. It will be up to the door manufacturer to experiment to find the best solution.

What is the difference between reaction to fire and fire resistance?

Reaction to fire refers to the tests carried out on an individual material, in our case HPL. Fire resistance, however, is measured by tests on the finished article, i.e. the composite panel formed of HPL, the substrate on which the laminate itself is applied, the bonding or fixing system and any supporting structure. Typical examples of this latter type are the doors or ventilated cladding for building façades.


How can HPL be disposed of?

HPL is not a dangerous product and requires no special treatment. Thanks to its high cellulose content, the laminate can be used for energy recovery at the end of its life cycle, in incinerators authorised for municipal waste. In the factory, waste materials are used as fuel to generate the energy needed for manufacturing. The residual ash can be treated as solid municipal waste (EAK Code 120105).

Is HPL a chemical product?

No. It is not a chemical substance but a thermosetting plastic material whose physical and chemical characteristics are completely different from those of the raw materials it is made from. During the high-pressure process, the resins that the sheets are originally impregnated with undergo an irreversible reaction, producing a stable and non-reactive material.

Is it true that HPL does not release formaldehyde?

The formaldehyde emission of Arpa’s HPL does not exceed 0.03 ppm with the EN 717-1 chamber method and 0.4 mg/m2/h with the EN 717-2 gas analysis method. This level is far below the minimum required in Europe for wood based panels used in furniture. In addition, given its very low permeability, when HPL is combined with a wood-based panel, it acts as a barrier against possible formaldehyde emissions from the substrate itself.

What is the average life of a sheet of HPL?

The life expectancy of HPL laminates is much longer than that of a human being! A piece of furniture finished in HPL is not easily damaged. Of course, the actual lifespan depends on how it is used, especially as regards the decorative surface. In any case, its durability is another of its considerable qualities and helps to make it especially attractive from an environmental point of view as well. Long life means less waste and a saving in resources.


How is HPL cleaned?

A simple cloth dampened with hot water is almost always sufficient, because the surfaces of HPL are compact, not very porous and are resistant to the stains and chemicals commonly used in a domestic environment. Of course the less textured finishes can be cleaned more easily.

Is it possible to use any cleaning product or are there products to be avoided?

Almost all normal household cleaning products or disinfectants are tolerated perfectly well, as long as they are not abrasive or strongly acidic or alkaline. Bleaches or heavily chlorinated products should also be avoided. After cleaning with detergent, rinsing and thorough drying is advisable, to prevent stains. It is not necessary to use furniture polish or wax based cleaners to maintain the surface sheen and indeed, these eventually form deposits on the surface that absorb dust and dirt.

As regards surface stains, to which substances is HPL resistant and which are the ones to avoid?

HPL has a good resistance to most substances that can cause stains, including syrups, fruit juices, jams, liqueurs, milk, tea, coffee, wine, soap, ink, citric acid and acetone. It is as well, however, to remove products such as cranberry or beetroot juice, concentrated tomato or fruit juices, caramel and some very strong sanitary bleaches as soon as possible.

Is it true that HPL is especially hygienic?

Yes, absolutely. An HPL surface is unfavourable terrain for the growth of germs and is therefore a material ideally suited to all situations that require maximum hygiene, from kitchens to operating theatres.


How long does the sample delivery take?

Arpa’s Quick Sample service ensures the rapid delivery of samples in A4 format, in the decor and finish chosen. Timescales will vary, however, depending on the destination. For an accurate estimate, please contact Customer Service.

What are the essential elements in establishing product specifications?

These are some of the essential criteria:
– colour of the decorative finish
– thickness
– surface finish
– grade (e.g. standard, vertical or postforming)
– sheet size
– fire resistance (standard or flame-retardant)
– field of application (construction, shipbuilding, transport, furniture, etc.)
– use in wet or dry environments
– the substrate used for bonding and the balancing material
– fixing or bonding method

For solid colours, can Arpa provide RAL, Pantone and NCS references?

Where possible the RAL, Pantone and NCS references are shown. In every case these are indicative references which should always be confirmed visually. For precise information you can always contact Customer Service.

On average, how long does it take to fulfil an order?

The 311 decors in the Arpa for You collection are all available for rapid delivery. For decors in the other collections, times can vary depending on the specific references and quantities required. For precise details please contact Customer Service.

If the laminate is to be used in applications which legally require special markings, can Arpa issue a certificate?

Yes, of course, but it is important that the request is made at the time of ordering. In such cases, Arpa will be responsible for confirming compliance and, if confirmed, for marking the panels and/or issuing the required certificates and declaration of conformity.

Which RAL reference is given in the catalogue? Classic or design?


Where can details of the properties of Arpa laminates be found?

The latest Technical Data Sheets can be downloaded from Arpa’s website, in pdf format.

Can I order any finish with any decor?

Not every decor is available in all finishes. In the catalogue or by selecting the decor using the search facility on the website, you can easily check which finishes are available. For any further queries, please contact Customer Service.

How can I decide the size of the panels?

The sheet size the customer can order depends on what it is to be used for. The Customer should check the sizes available at the design stage. For solid colours and certain decors, maxi-sizes are available and are ideal for shower enclosures.

Once the decor and finish have been chosen, can I order the panels in any size or thickness?

Again, the catalogue or the search facility on the website will provide information on the thicknesses and sizes available for each reference. For any further queries, please contact Customer Service.

The colour shown in the catalogue looks slightly different from the colour of the sample. Which one should I rely on?

The colour of the sample is always the one to rely on. The design images in the paper catalogue may suffer from all the variations in tone and colour that printing processes are liable to. Equally, the design images on the website are as close as possible to reality but the colour fidelity depends essentially on the computer systems used as well as on the User’s graphics card and monitor settings. So these images are only to help the Customer make an initial selection and ask for samples to examine.


Can HPL be purpose made in any finish and thickness?

In many cases this is possible but a thorough assessment of both the costs and manufacturing feasibility is necessary on each occasion. Once the finish and decor have been selected, the Customer and Arpa Sales staff will assess what thickness and type of laminate is best for the specific application. For information Customer Service should always be consulted.

Can HPL be ordered purpose-made in any size and shape?

For special projects, the Arpa Custom service offers the option to customise designs and finishes, starting with the sizes available, as well as special treatments (e.g. cutting, routing and perforation).

Is it possible to create panels with special decors, with purpose made designs, for example?

Yes. For example, with digital technology, HPL panels can be made with any image or drawing incorporated, including special designs. For information please contact Customer Service.

Is it possible to design a purpose made product, to suit particular applications and specific performance requirements?

This depends on the scale of the project of course and prior analysis is required on the profitability and feasibility of the request. After checking the particular features, however, Arpa Lab is at our customers’ disposal for designing and considering, with them, the best solutions for each individual situation. It is precisely this sort of cooperation that can result in the most innovative products.

Can the panels be customised with a logo?

Of course. Digital technology enables us to incorporate logos and graphic images on the HPL sheets, to customise any application or installation. For information please contact Customer Service.


Can the laminate be applied directly to the walls that are to be clad?

Absolutely not if they are functioning, plastered or painted walls, for many reasons: because of the natural surface irregularities that do not allow good adhesion, because of the moisture released from the bare wall, because adhesives do not perform well when hand-applied to plaster and because the dimensional movement of HPL, which differs from that of the wall, would create stresses and possible cracking. To prevent the laminate warping, it is good practice and an indispensable rule “to let it breathe”, isolating it from possible sources of moisture. In conclusion, the laminate must be applied to a framework or support that is then fixed to the wall.

Can HPL be used for signage?

Yes. Digital technology makes it possible to incorporate any kind of sign or wording, with perfect results. For information please contact Customer Service.

What precautions are recommended for applications intended for dry or wet environments?

The success of applications intended for particularly dry or wet environments depends essentially on the choice of substrate and proper pre-conditioning of the materials. Where there are variations in humidity it is essential that the panel is symmetrical on both sides and that the humidity conditions are as similar as possible for both faces. Bear in mind that, as regards dimensional changes due to wet conditions, the laminate is similar to wood, so products need to be designed using appropriate adhesives, leaving adequate moisture escape routes and making screw holes a little larger. For information, please refer to Customer Service.

Are there recommended decors and/or finishes for particular applications?

The choice of pattern and/or finish is important both from an aesthetic and functional aspect. There are big differences, for example, between a worktop potentially subject to heavy wear and tear, a small vertical door of a little used piece of furniture and a building façade subjected to the weather, heat and sunlight! In general we can say that surfaces with more textured surface finishes and lighter colours offer better performance in terms of scratch resistance and abrasion than dark and glossy ones. Equally, smooth surfaces or those with a fine texture are easier to clean than those that are heavily and deeply textured. For information, please refer to Customer Service.


In what circumstances should HPL Compact be chosen and how is it handled?

This is a particularly versatile grade of HPL, a strong, durable and homogeneous material, with excellent dimensional stability. It is much thicker than normal laminate and usually has the decor on both sides. Because of these properties it is often used to create partitions and wall coverings in densely trafficked public spaces, lockers or cubicles in damp environments such as swimming pools and gyms or laboratory benches.

What alternatives are there for finishing the edges of a worktop?

There are several options:
– using postforming HPL and bending it, as the design requires
– bonding a strip to the edge, of the same HPL as used for the surface
– with PVC, bonding a strip to the edge
– with wood, gluing a strip to the edge of the composite panel
– with Arpa Unicolor HPL, borders are not necessary, as this product has a core of the same colour – as the surfaces (full colour).

Can I make internal cuts without risk of the panels splitting or cracking?

Yes. Rounded corners need to be formed (5mm radius) and 90° angles avoided at all costs. Care should be taken, when forming notches and holes, not to induce micro cracks that could degenerate into real splits in the long term. In addition, the composite panel must have been manufactured with rigid or semi-rigid adhesives and, of course, with suitably pre-conditioned materials.

What should be done to make sure the composite panels do not warp?

To counterbalance the effects of possible variations in material sizes, it is almost always necessary to apply a sheet of laminate to the back of composite panels, as similar as possible to the one on the front, (preferably of the same thickness, from the same manufacturer and cut in the same direction). In addition, simultaneous pre-conditioning of the substrate, the laminate and the balancing sheet is essential prior to bonding.

Can metallic laminates be worked and bent like the others?

Metallic laminates require special attention but they can be worked with the normal equipment used for all laminates. Metallic laminates are also available for postforming. For detailed information on these processes, Customers can refer to Arpa’s technical documentation or contact Customer Service.

What are the most suitable substrates for HPL?

Plywood, particle board and MDF are all particularly suitable because, like the laminates, they are cellulose based and therefore have similar dimensional movement. In some industries and applications they require special substrates such as mineral fibre boards, sheet metal, foam or honeycomb panels etc. These materials all require special bonding and manufacturing techniques. Before proceeding with application, it is always advisable to check with the Arpa technicians.

What substrates can be used for metallic laminates?

Compared to other high-pressure laminates, metallic ones require greater care in the choice of substrate and adhesive. To achieve good results, the substrates should be perfectly smooth and the surfaces free from any undulation or blemish. Various adhesives (other than those that are urea based) can be used but the best results are obtained with a very evenly spread PVA type adhesive (which has no tendency to shrink) because this minimises the risk of irregularities extending over the finished surface.

Can the laminate be bent?

When the laminate needs to be bent, the “postforming” grade should be chosen (either HGP or VGP); this retains all the properties of HPL but is also capable of being hot formed into either concave or convex shapes. For detailed information customers can refer to Arpa’s technical documentation or contact Customer Service.


Can the laminate be transported or stored rolled up?

In general it is better to handle the sheets carefully, keeping them laid flat and using pallets of appropriate size and stability. Only very thin sheets can be transported rolled up, with the decorative face on the inside and in rolls about 600mm in diameter.

Are there any special precautions for the storage of HPL?

The panels should always be placed on flat, horizontal shelves, in pairs, with the decorative sides facing inwards. They should be well protected from dust and, in the case of laminates of limited thickness, from accidental stresses that may mark the surface. If horizontal storage is not possible, they can be placed in slightly inclined (60 / 70°) vertical stacks with support provided across the entire area of the sheets to keep them flat.

Are special temperature and humidity conditions required in warehouses?

Decorative laminates should be kept in closed rooms and under normal environmental conditions, approximately at a temperature of between 10 and 36° C and humidity of 60 / 65%.




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