Neoprene (Contact) Adhesives and PVA Glue

To glue wood use a PVA with a D class, according to EN 204: D2 is for interiors with occasional water exposure, D3 for interiors with high humidity, and D4 for higher water resistance. For a kitchen cabinet or a window exposed to moisture, choose at least a D3. For outdoor exposure to rain, look for explicit indications on the data sheet.

Fast-setting PVA glues, such as Vinavil Pro Super Fast D2 or Pattex Legno Express, fix the piece in a few minutes and allow the joint to be worked soon after. They are handy for woodworking and small jobs, but full curing takes longer. For joints under load, allow the stated time, clamping the piece with clamps or straps.

Hardeners improve the water resistance of wood glue, as indicated for the D4 Unifix hardener in the catalogue. They must be mixed in the doses stated on the pack and used within the working time. They do not make the glue suitable for direct, prolonged outdoor exposure, for which dedicated products are needed. Note the mixing date, as prepared glue does not keep long.

Neoprene contact adhesive is applied to both surfaces, left to dry, and then the pieces are joined: the bond is immediate and needs no clamps. It is used for laminates, rubber, leather and dissimilar materials that PVA does not bond. Use it in a ventilated area, as the vapours are flammable. The gel type is easier to spread on vertical surfaces.

For leather, rubber and plastic there are specific adhesives, because the material determines compatibility. Leather adhesive bonds flexible surfaces, while rubber adhesive suits elastomeric materials. For plastic, check the type of polymer, as some materials, such as polyethylene and polypropylene, are difficult to bond even with specific adhesives.

Clean and sand the surfaces to be bonded, then spread a thin, even layer of glue on both. Join the pieces within the stated open time, then clamp them with clamps or a press and remove the excess before it sets. Let it dry for the stated time before loading the piece.

Neoprene contact adhesives contain flammable solvents, and their vapours can irritate the respiratory tract and skin. Use them in a ventilated area, away from flames, smoke and switched-on electrical equipment, and wear gloves. Keep containers closed and dispose of residues according to the safety data sheet. The employer assesses chemical risk under D.Lgs. 81/2008 (Italian Legislative Decree 81/2008 on workplace safety).