Following the recent acquisition of a hydraulic hot press for our facility, we are encountering challenges in applying wood veneer to 3/4" UV plywood, resulting in improper bonding and bubble formation. We require expert guidance on optimal adhesive selection (hot or cold press), ideal press time and temperature parameters, and appropriate glue layer thickness to achieve successful veneer adhesion. Any insights from experienced professionals would be highly valued..

I'm not surprised you are having problems with UV coated plywood. That surface is very smooth and impermeable. PVA and urea formaldehide glues need to wet the wood fibres. I'm not sure but I believe that resorcinal needs to as well. Your other options are epoxy or poly urethane glues. Neither are ideal for hot pressing. You certainly don't want them curing to your platens.
Your alternative is to buy finished one side plywood and use either PVA or UF.

Thank you for your contribution, Tom. To clarify, the UV plywood is currently being sanded; however, we have now ordered single-sided UV plywood, which we expect will rectify the problem. We will proceed with PVA adhesive, with UF adhesive as a potential alternative.

Be aware that veneering to one side of the plywood will likely cause warping. You will be adding moisture to one face and veneer then as that moisture evaporates the panel will tend to distort. Keep the sheets away from air flow to slow the evaporation and allow the moisture to normalize slowly.
I am pressing at 60 degrees C for about 10 minutes using Type 2 PVA.

We recently started using a hydraulic hot press for veneering 3/4" UV plywood, but we’re facing issues with bonding and bubble formation. I suspect the problem could be related to the adhesive type, press time, or temperature settings. We’re unsure whether a hot or cold press adhesive would work best and what the optimal glue thickness should be. Adjusting pressure and ensuring even glue application might help, but expert advice would be greatly appreciated. If anyone has experience with similar challenges, I’d love to hear your recommendations!

For veneer adhesion issues, selecting the right adhesive is crucial. For hot pressing, consider using a urea-formaldehyde adhesive, which is suitable for its quick cure and strong bond. Ensure the press temperature is around 195-210°F (90-100°C) and maintain sufficient pressure, typically 150-200 psi. Press time usually ranges from 3-5 minutes but may vary depending on specific materials. Thin, even layers of glue reduce bubbling—consider spreading it with a roller or glue spreader for consistency. Testing different combinations on small samples might help fine-tune the process.

I’ve worked with veneer applications on UV-coated plywood before, and a few parameters can make a big difference in avoiding bubble formation and poor bonding:

Adhesive Selection: For UV-coated or prefinished plywood, cold press adhesives often don’t penetrate well. A modified urea-formaldehyde (UF) or specialized hot press adhesive with good heat resistance tends to perform better. Phenolic or melamine-urea resins can also be considered if high durability is required.

Glue Spread & Thickness: A uniform glue spread of around 150–180 g/m² is usually recommended. Too thin a layer causes weak adhesion; too thick traps moisture and leads to bubbles.

Press Temperature & Time: For hot pressing, 110–120°C with a dwell time of 6–8 minutes (depending on thickness and adhesive type) generally works well. Cold pressing requires longer curing times, so ensure enough pressure and curing duration.

Surface Prep: Light sanding or primer treatment of the UV plywood improves adhesive penetration.

For more advanced formulations, you might want to look at I R Tubes Pvt Ltd, who supply specialty chemicals and adhesive solutions for wood, veneer, and rubber applications. Their technical team has experience tailoring adhesives to specific substrates, which can be very useful when dealing with coated plywood challenges.

I.R.Tubes Pvt Ltd