A simple guide as to what a D4 PVA wood adhesive is, what it can bond, and how to use it.
Woodstikk D4 PVA is a single component PVA wood adhesive with excellent water resistant characteristics.
Ensure that the surfaces to be bonded are smooth, clean and free from dust or other deposits. Wood, plywood, laminated plastics should be of uniform thickness. Some dense hardwoods may require sanding before bonding. For best results the moisture contents of the surfaces to be bonded should be in the range of 7 – 13%, but when pressing at temperatures above 105°C, moisture content should not exceed 10%. Moisture content variation between adjacent components should not be > 3%.
Woodstikk D4 PVA should be applied evenly to one substrate using a brush, hand roller or mechanical roller. Adhesive coverage between 80 and 180g sq/m are suitable depending on the surfaces to be bonded. When bonding different timbers, such as teak and high-density hardwoods, the adhesive should be applied to both surfaces of the joint. It should be noted that adhesive spread has considerable influence on both assembly and setting times.
Ideally open assembly time should not be more than 5 minutes.
Lay the items to be bonded together within the workable time and press them for as long a time as is needed to achieve the required handling strength. The pressure should be high enough to ensure contact of the parts over the entire area of the joint. Allow 24 hours for full strength to develop. Higher levels of water resistance form more slowly and should be tested not earlier than 7 days after bonding.
Woodstikk D4 PVA like all other PVA adhesives, may tend to show structuring especially in cold conditions. This effect is generally reversible on slight stirring. Additionally, there may be some increase in viscosity, but this will not detract from the application properties or performance.
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.
Clean machines, equipment and tools with water before the adhesive dries.
Woodstikk D4 PVA should be stored in the original containers in a cool, dry place, at a temperature range of between 10°C and 30°C. In these conditions it has a storage life of at least 6 months, but it is important to note that Woodstikk D4 PVA does have limited stability and is prone to thickening. Woodstikk D4 PVA must not be allowed to freeze and ideally should be warmed to at least 15°C before use.
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.
A quick run down on the key differences between the different D grades of PVA and PU wood adhesive.
A simple guide as to what a D3 PVA wood adhesive is, what it can bond, and how to use it.