Service And Advice

H.B. Fuller

We are the adhesive experts!

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:

Standard Products

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