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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:
We offer a range of products to suit these needs including:
D2 Express 45N
high viscous PVA glue which sets quickly at normal temperatures and faster still under heat. Application: Gluing joints in hard & soft woods. Carcase and assembly gluing
D3 GLX 3
easy to apply and suitable for many processing conditions. Provides very strong bonding
D3 ECO 3
easy to apply and suitable for many processing conditions. Recommended for UF replacement
D4 GLX 4
one-component adhesive with excellent water resistance. Offers fast setting times, strong adhesion to many difficult-to-bond woods, colour of glue line maintained despite typical process heat
D4 ECO 4
one-component adhesive emulsion, suitable for many processing conditions
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: H.B. Fuller
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