Plywood QC Inspection Checklist : Part 25 Test of Water Boiled Proof plywood

Plywood QC Inspection Checklist : Part 25 Test of Water Boiled Proof plywood

When doing boiling experiments, we can simply make the following requirements:

1. Size of plywood samples

2. Time Recorder

3. tweezers

4. Water temperature thermometer

5. Boiling label or waterproof pen

6. Batch and order number of plywood production

7. Thickness and number of plywood layers, glue grade

8. quality inspector

9. Inspection time

The best and simple way to test the plywood is using boiling water test .In factories, prepare simple gas cookers or rice cookers, a clock, and  plywood samples with required sizes and thickness .If the factory has a special laboratory, it is best to test the boiling resistance of plywood in the laboratory.

Most WBP glues are either melamine or phenolic glues. Lower quality melamine plywood can sustain 4-8 hours boiling without delaminating. Higher end melamine can last between 10-20 hours in the boil test.

Phenolic plywood is considerably more resistant (24-72 hours). The best phenolic glue can be regarded as essentially permanent adhesives and are used in the higher grades of Marine Plywood.

According to different quality plywood products, in order to test their plywood quality, I listed several different methods to test the plywood bonding strength quality, will take a specific look according to their introduction.

1. Measuring dimensions in plywood specimens .

2. According to the different types of plywood in the specimens, there are the following ways to deal with them:

2.1 Class I plywood: boil the sample in boiling water for 4 hours, then dry it for 20 hours in an air convection drying chamber at 63  C, then eat and boil for 4 hours, then cool it at room temperature for 10 minutes. Covered and boiled specimens were immersed in boiling water.

Note: The factory in production can carry out rapid inspection method of boiling for three hours, multiply the measured results by 0.9 as the bonding strength value of product inspection. If there are different disputes between the supply and demand sides for re-inspection of type I plywood, the 28-hour boiling-drying cycle method can still be used as a cutting promotion method.

2.2 Class II plywood: The specimen is dipped in hot water for 3 hours and then cooled for 10 minutes at room temperature after being taken out according to the previous method. This is to immerse all the specimens in hot water and cover them.

Note: Rapid inspection method of 63 C and impregnation for 1 h is allowed in factory production. The measured results multiplied by coefficient 0.82 are used as the bonding strength value of product inspection. However, in case of disputes between suppliers and demanders, the method of 3 h hot water impregnation is still used as the arbitration method.

2.3 Class III plywood: After two hours of immersion in water at 63C, each specimen was separately placed in an air convection drying box for about 63 C for one hour, and then taken out for 10 minutes.

2.4 IV plywood: The moisture content of the specimen meets the standard requirements for dry test. Note: The moisture content of specimens should be controlled from 8% to 12%.

WBP is the abbreviation of “Water Boiled Proof” in English. “Water Boiled Proof” means weather-resistant, boiling-resistant or steam-treated. If WBP glue is used for plywood and cladding board, the board can be used outdoors (weather-resistant), waterproof (boiling water is no problem), moisture-proof (boiling water is not afraid, not to mention moisture-proof). Similar to the meaning of “MR glue”, WBP glue is not the name of a certain kind of glue. WBP is a characteristic, characteristic or characteristic of a certain kind of glue. If a glue has the characteristics of WBP (Water Boiled Proof), it can be called WBP glue.

The simple way to test the weather resistance of WBP plywood and WBP plywood is to boil the sample in boiling water. If the sample does not delaminate in boiling water for a long time, we can say that the plywood has the characteristics of weather resistance and water boiling resistance, and the plywood is weather resistance and water boiling resistance (WBP) plywood.

WBP plywood

The common WBP adhesives are trimelamine adhesives and phenolic adhesives. Generally speaking, ordinary tripolymerized plywood can remain unglued for about 4 to 8 hours in boiling water. Good tripolymer plywood can be kept in boiling water for more than 10 hours or even 20 hours without delamination. Normal phenolic plywood can keep in boiling water for about 24-72 hours without delamination. The best phenolic glue is the permanent glue, and the corresponding plywood is difficult to delaminate in boiling water.

It should be noted that the climatic and boiling resistance of plywood depends not only on the quality of WBP glue, but also on the production process and core board quality.

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