What is the difference between D1, D2, D3 and D4 PVA and PU wood glues?

A quick run down on the key differences between the different D grades of PVA and PU wood adhesive.

Key Infomation

A quick run down on the key differences between the different D grades of PVA adhesive.

Product Examples

Woodstikk® D3 PVA Woodworking Adhesive

Woodstikk® D4 PVA Woodworking Adhesive

Aro-Bond® 535 D3 Laminating Grade Adhesive

Aro-Bond® 540 D4 All Purpose Adhesive

Woodstikk PU D4 Polyurethane Adhesive

Woodstikk PU Rapid D4 Polyurethane Adhesive

Woodstikk PU Gel D4 Polyurethane Adhesive

Woodstikk PU Rapid Gel D4 Polyurethane Adhesive

D references of adhesives are commonly used to identify the water resistance of wood bonding adhesives, but strictly speaking they relate to the durability of the adhesive, not just the water resistance. The standard used to determine the durability class is EN 204: 2001 – “Classification of thermoplastic wood adhesives for non-structural applications”.

Practically D1 and D2 are considered to be “interior grade” adhesives and should not be used anywhere where a high level of durability is required.

D3 adhesives are often referred to as “water resistant” and D4 adhesives are referred to as “waterproof”. Whilst this gives a simple way of identifying the difference, it is not strictly true to say that D4 is “waterproof”. The official description of the durability classes from the EN204 standard is shown below and this gives context around what you can expect the bond performance to achieve.

If you require a fully “waterproof” adhesive for bonding wood, you will need to use a phenol resorcinol resin system, e.g. Prefere 4050, or a melamine urea resin system e.g. Prefere 4535.

DESCRIPTION OF DURABILITY CLASSES

D1 = Interior, in which the moisture content of the wood does not exceed 15%.

D2 = Interior 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 with frequent short-term exposure to running or condensed water and/or to heavy exposure to high humidity. Exterior not exposed to weather.

D4 = Interior with frequent long-term exposure to running or condensed water. Exterior exposed to weather but with protection by an adequate surface coating.

EXAMPLES OF THE DIFFERENT D GRADE ADHESIVES

D2 ADHESIVES

Aro-Bond® 506 PVA adhesive

D3 ADHESIVES

Many PVA adhesive manufactures make D3 PVA's and they all perform very well. H B Fuller (with their Rakoll brand), Bostik (with their Evo-stik brand), Everbuild and Jowat are some large manufacturers who make D3 PVA's, but most other brands purchase their D3 PVA in bulk from big polymerisers throughout Europe and pack it down into smaller pack sizes.

If the grade is classified as D3, then that means that it should have gone through the testing to ensure that it does meet the requirements, which give it its water reisistance. The full D3 classifcation is set out in the EN 204 standard.

Some D3 grades from our range include;

D4 ADHESIVES

Many PVA adhesive manufactures make D4 PVA's and they all perform very well. H B Fuller (with their Rakoll brand) and Jowat are two main polymerisers who make D4 PVA's, but most other brands purchase their D4 PVA in bulk from big polymerisers throughout Europe and pack it down into smaller pack sizes.

If the grade is classified as D4, then that means that it should have gone through the testing to ensure that it does meet the requirements. The full D4 classifcation is set out in the EN 204 standard.

An additional certification for D4 PVA adhesives which indicate the quality of the grade is whether they comply to EN 14257 (WATT91). This standard tests the heat resistance of the adhesive, but not all of them comply.

Another feature to look out for is the shelf life. D4 PVA is less stable than D1, D2, and D3 adhesives and most of them only have a recommended shelf life of 3 months. There are a handful, including Woodstikk D4 PVA, which have a shelf life of 6 months if stored correctly.

All PU adhesives which are single component MCPU adhesive are likely to conform to the D4 requirements by default as polyurethane is extremely tough and weather resistant.

WATCH HOW TO USE A D3 PVA WOOD ADHESIVE

How to use a D3 PVA Wood Adhesive

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The Pfohl adhesive spreader used in this video is the benchmark in the industry for applying adhesive to panels and boards. It is suitable for use with PVA and EVA water based adhesives and UF, MUF and PRF formaldehyde resins.

Learn more here

If you would like to discuss these options in more detail, please contact us on 0117 971 1364 or email us on sales@thenamethatsticks.com.