HDO High Density Overlay

HDO High Density Overlay adds stability, repels foreign substances from the surface, and provides a smoother and more durable forming surface. The phenolic resins used in overlay production HDO are hard and resist moisture, chemicals, and abrasion. HDO High Density Overlay is often utilized where the smoothest possible concrete finish and maximum number of reuses is desired.

HDO High Density Overlay has a resin content of 52 to 58 percent and appears smoother to the touch than does MDO. Hotels, high rise office buildings, museums, power plants, civil projects, and large-scale residential projects are common applications for HDO concrete forming panels. Panels are manufactured as one-sided or two-sided panels varying in thickness. Contractors can expect 25-50 reuses depending on the application, proper handling, care, and treatment with an appropriate release agent.

HDO High Density Overlay impart a nearly polished concrete surface. Both sides of HDO are moisture resistant but cannot always be used to form concrete with equal effectiveness unless specifically made for that purpose.

The abrasion-resistant surface should be treated with a release agent prior to its first use and between each pour to preserve the surface and to facilitate easy stripping.

This Plyform panel satisfies the exact same basic specifications as Plyform Structural I or Class I. All types of HDO Plyform possess a tough, semi-opaque coating of thermosetting phenolic resin-impregnated material that creates a lasting, continuous bond using all the plywood. At a media, these overlays are secured to the plywood under pressure and heat during plywood manufacturing.

High Density Overlay (HDO) Plyform

This Plyform panel meets the same general specifications as Plyform Structural I or Class I. All classes of HDO Plyform have a hard, semi-opaque surface of thermosetting phenolic resin-impregnated material that forms a durable, continuous bond with the plywood. During plywood production, these overlays are bonded to the plywood under high heat and pressure in a press.

The function of the overlay is to add stability, repel foreign substances from the surface and provide a smoother and more durable forming surface. The thermosetting phenolic resins used in overlay production are hard and resist moisture, chemicals and abrasion. HDO is most often specified where the smoothest possible concrete finish and maximum number of reuses is desired.

The abrasion-resistant surface should be treated with a release agent prior to its first use and between each pour to preserve the surface and facilitate easy stripping. HDO Plyform is most often specified when the smoothest possible concrete finishes are desired, because the panel has a hard, smooth surface. It can impart a nearly polished concrete surface. Both sides of HDO are moisture resistant but cannot always be used to form concrete with equal effectiveness unless specifically made for that purpose. Scratches and dents in the backs caused by fastening the panels to the supports may make the use of both sides impractical.

Various grades of HDO Plyform may be available; check with your supplier. With reasonable care, HDO Plyform will normally produce 20 to 50 reuses or more. Some concrete-forming specialists achieve 200 or more reuses with good results.

MDO and HDO Plywood

 

 

Medium Density Overlay (MDO) and High Density Overlay (HDO) Plywood (also called signboard) are engineered wood panels, originally designed for sign makers. However, they are gaining popularity for other purposes. Cabinetmakers are beginning to see the value of these engineered woods and use them. They are also excellent products for jigs and cement forms.

Surfaces

Both MDO and HDO are hardwood plywoods with a resin soaked fiber overlays between the veneer layers and on both surfaces. The top veneer layer on both sides is “A” grade, providing for an extremely smooth surface, without voids, to apply the fiber overlay. The resin-soaked fiber overlays are applied with heat and pressure, forming an extremely strong, extremely flat and extremely smooth engineered wood product that is waterproof. The only differences between the two products are that the density of the exterior fiber layer on the HDO is considerably higher than for MDO and it is manufactured with higher resin content.
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Thickness

MDO and HDO are both available in a variety of thickness, including 3/8”, 1/2”, 5/8”, 3/4” and 1”. Standard sheet sizes include both 2 and 4 foot widths, and lengths of 8’, 10’ and 12’.

Painting

When used for cabinetmaking, MDO panels provide an excellent, very flat surface that accepts paint very well. The resin impregnated fiber layer adheres well to paint and eliminates the need for priming. Unlike many other materials, cut edges are still highly water resistant, with the added benefit of being easily painted, fully sealing the edges against water.

Application and cost

HDO plywood was originally created for use in making highway signs where reflective material is attached to the surface of the sign. To make a more durable sign, it was decided that a more robust resin layer was needed in order to provide a better surface for attaching the reflective material. These materials are not as commonly available as softwood plywood. Consumer building supply centers normally will not carry them, but lumberyards that cater to professions probably will. MDO plywood costs about half the cost of marine plywood, or about twice the cost of softwood plywood; HDO is slightly higher.

FINNFORM

 

The superior hardwood strength properties of Finnish White Birch combined with thin multiple veneer panel construction makes FinnForm the benchmark for quality in the plywood forming industry. The 220g/m2 phenolic surface film on both faces provides very high reusability while producing good, well-compacted concrete. That is why architects and specifiers select FinnForm for high profile concrete projects throughout the country. There is only one FinnForm—easily identified by its red colored film faces. FinnForm is available in thicknesses from 1/4″ to 1 1/2″. Standard sizes are 8’x4′, 5′; 10’x4′, 5′; 12’x4′, 5′

A special FinnForm panel is available for re-plying metal framed forms. This is FinnForm Reply, manufactured in full 1/2″ thickness, 4’x8′ size (face grain runs the length direction). The durability of FinnForm plywood out performs HDO and lasts longer. So, when replacing (re-plying) your metal framed forms, FinnForm Reply is the way to upgrade your forms.

Euroform Plywood
Euroform is made with the same high quality construction as Eurobirch with the addition of thermally fused phenolic facings for durability and moisture resistance. It is excellent for pattern plates or core box construction. Euroform features:
• Solid Birch construction
• Virtually void free laminates
• Phenolic resin adhesive that is waterproof & boilproof
• Thin veneers for maximum strength & durability

Special thanks for the original source of :

1.https://www.performancepanels.com/hdo-high-density-overlay-plyform

2.https://chesapeakeplywood.com/hdo-high-density-overlay/

3.http://www.uslumberinc.com/hdo.html

4.http://paneltechintl.com/high-density-overlays/

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