Wood glue is adhesive made specially to join wood to wood. The most commonly used type is white wood glue based on PVA (polyvinyl acetate), but there are also PU glue (polyurethane), epoxy and traditional glues such as bone glue. A good wood-glue joint is often stronger than the wood itself: under load the wood breaks before the glue line does.
Stress classes (EN 204)
For moisture resistance, wood glues are classified into classes according to the standard EN 204:
- D1 — for indoors, dry conditions
- D2 — indoors, occasional brief moisture
- D3 — indoors at high humidity and limited outdoor use (not in direct weather)
- D4 — highest water resistance, also for outdoor use
Choose the class based on the location: for an exterior door or garden furniture at least D3, preferably D4.
How to glue wood well
- Clean and fitting — the parts must be clean, free of dust and grease and fit together well
- Thin and complete — apply a thin, covering layer to both surfaces
- Clamp — press the parts together with clamps and observe the stated pressing time
- Open time — work the glue within the open time the manufacturer states
- Excess glue — wipe away squeezed-out glue before it cures, otherwise the wood will not take stain or lacquer there
Related terms
- Glue
- Timber
- Timber joints
- Epoxy glue
- Polyurethane
- Open time
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