Guides / Specification
MR, Melamine or WBP: Which Bond to Ask For
September 21, 2026
Bond is the line buyers get wrong most often, and it is the one that costs the most to get wrong. The panel looks the same on the pallet. The difference shows up on site, after the first wet week.
Vietnam mills press with three glues. Here is what each one is for.
MR: urea formaldehyde
Moisture resistant, which in practice means interior only. It is the cheapest bond and the one a mill quotes when your enquiry does not name a glue.
- Right for packing plywood, crates, pallet tops and furniture carcases that stay dry
- Fails when the panel is rained on, stored outside or used in a wet trade
- The glue line is pale and almost invisible on a cut edge
If your panel lives inside a finished building or inside a crate that crosses one ocean, MR is not a compromise. It is the correct answer, and paying for phenolic would be waste.
Melamine: urea fortified with melamine
A middle grade. The melamine share decides how much better it is than plain MR, and that share is not visible on the panel, which is why the word melamine on its own tells you little.
- Right for interior work in humid climates, kitchen and bathroom carcases, furniture shipped through tropical ports
- Handles short wetting and drying, not repeated cycles
- Costs above MR and below phenolic
Ask what percentage of melamine the mill uses, or ask for the glue brand. A mill that presses real melamine bonded panels will answer. A mill that mixes a token amount will change the subject.
WBP: phenol formaldehyde
Weather and boil proof. Dark glue lines, visible as thin brown stripes along a cut edge. This is the bond for anything that meets water.
- Required for film faced formwork, exterior joinery, marine type panels and transport flooring
- Survives the boil test, which is the whole point of the name
- Runs well above MR on price, so no mill uses it unless you ask
A film faced panel pressed with MR glue is the classic substitution. The film hides the panel face, water gets in at the cut edges on every pour, and the plies open after the second or third cycle. See the film faced specification guide for the rest of that spec.
How to read a glue line
Cut an edge clean and look at it in daylight.
| What you see | What it usually is |
|---|---|
| Pale lines, almost the colour of the wood | Urea, plain MR |
| Light brown lines, thin and even | Melamine fortified urea |
| Dark brown to black lines, clearly visible | Phenolic |
This is a first check, not proof. Some mills tint urea glue darker. If the bond matters, take a sample from the production batch and have it tested rather than judged by eye.
The test that settles it
The boil test is simple enough to run in an office. Cut a 100 mm square from a panel, boil it for four hours, dry it in an oven or in the sun, and look at the plies. Phenolic holds together. MR opens. Some standards run boil, dry and boil again, which is harsher and closer to what formwork sees.
For structural or exterior work, skip the kitchen version and ask the mill for a laboratory report on your batch. A mill that presses real WBP will have one or can get one. A mill that cannot produce a report on any batch is telling you something.
Writing it into the contract
Three lines are enough, and all three matter:
- Bond by name: “phenol formaldehyde, WBP” or “melamine fortified urea”. Never the words waterproof or water resistant.
- Evidence: a boil test report from the production batch, not a certificate from last year.
- Substitution clause: the mill tells you before changing the glue, and the shipment is yours to reject if it does not.
Most bond problems are not fraud. They come from an enquiry that said waterproof, a sales office that read it as melamine and a press that ran what was already loaded. Name the glue and the problem disappears.
What it means for your price
Bond is the second biggest line in a plywood quote, after the core. That is why a quote that comes back far below the others is usually quoting a different glue. When you compare quotes, put the bond next to the number, and see whether you are comparing two prices or two products. The rest of the price is broken down in what drives the price of Vietnam plywood.
Frequently asked questions
What does WBP actually mean?
Weather and boil proof, a trade term for plywood pressed with phenol formaldehyde glue. It describes the glue line, not the panel. A WBP panel with a poor core still fails, it just fails without delaminating first.
Is melamine plywood waterproof?
No. Melamine fortified urea glue handles humidity and short wetting better than plain MR, and far worse than phenolic. Use it for interior work in humid climates, not for anything that sits outdoors or gets rained on.
How do I check the bond on a panel that already arrived?
Look at the glue lines on a cut edge, then run the cheap version of the boil test: cut a 100 mm square, boil it for 4 hours, dry it, and see whether the plies separate. A phenolic panel holds. An MR panel opens up. For anything structural, ask the mill for a lab test report on the batch instead.
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