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What are D2, D3 & D4 PVAc Adhesives?
The D grading stands for durability
These grading’s are part of the European standard BS EN 204 governing the classification of wood glues for non-structural applications.
There are 4 main types of durability grading, running from D1 to D4. The differences between these are listed below:
- D1 = Interior areas, where the temperature only occasionally exceeds 50°C for a short time and the moisture content of the wood is 15% maximum
- D2 = Interior areas, with occasional short term exposure to running or condensed water and/or to occasional high humidity, provided the moisture content of the wood does not exceed 18%
- D3 = Interior areas, with frequent short-term exposure to running or condensed water and/or heavy exposure to high humidity. Exterior areas not exposed to weather
- D4 = Interior areas with frequent long-term exposure to running or condensed water. Exterior areas exposed to weather
The classifications, the bond strength requirement for the different classes is listed below:
RAKOLL® EXPRESS™ DKN – Low viscosity doweling adhesive
RAKOLL® 4933 D3 PVAC ADHESIVE – Formaldehyde free D3 PVAc adhesive
RAKOLL® ECO 3 – D3 PVAc for flat lamination, door production and assembly
RAKOLL® ECO 4 D4 PVAC – One-component D4 PVAc adhesive
RAKOLL® EXPRESS 25 D – High quality D2 PVAc adhesive
RAKOLL® EXPRESS TO 50 – Fast setting D2 PVAc adhesive
RAKOLL® GXL 4 – High quality one component D4 PVAc adhesive
RAKOLL® GXL 4 PLUS – Extended open time one component D4
RAKOLL® GXL-3 – D3 PVAc with IMO Certification
RAKOLL®EXPRESS LK 50 – Higher viscosity doweling adhesive
SWIFT®TAK 4002 – D3 PVAc for assembly and surface lamination
Did you know…………………..
- D4 PVAc requires to be lacquered for external use to achieve full resistance
- Work must be carried out within the specified open-time. Pressing must happen within this period to ensure bond quality
- True D4 PVAc will have certification confirming their authenticity. Many companies offer D4 PVAc which are really D3 PVAc
- HB Fuller polymerise their own polymers making their PVAc unique to the market
- PVAc are not suitable for PVC foils
- PVAc can be used with PP foils however the foils must be primed so that bonding can occur
- PVAc should not be pressed above 70°c as it will soften the glue line.
- PVAc go down to -40
- D3 and D4 PVAc adhesives cross link. D2 do not
- If stacking the coat-weight may have to be increased to ensure you have a workable open time.
- D3 with hardener / pot life 24 hours
- To spray PVAc adhesives the viscosity must be below 4000mps
Posted in: Woodworking
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