ADHESIVES and GLUING VENEER

There are many adhesives on the market. Their use is dependant upon your equipment and expertise.

Contact Adhesives are an EASY way to glue down veneer, but the results can be very problematic. They all depend on a rubber glue line which is very stretchable and allows movement... Problems can develop - from delamination, to checking & cracks, to seam compression and separation. You also have to consider compatibility with the finish & hope it doesn't chemically break down the rubber bond (e.g. lacquer can actually melt the rubber glue line).

A Better Choice depends on the size of your project & your available equipment. Better glues all require at least a system of cauls & clamps, vacuum press, or commercial hydraulic press...

Plastic Powdered Resin - Urea resin powder with filler and catalyst. Long storage life, high water resistance, rigid glue line, no spring back w/reduced bleed through. Color - Tan. Assembly time up to 40 minutes. Cold Press time 4-6 hours. Allow the freshly applied glue to "flash" for about 15 minutes before pressing for best results on thinner veneers in a cold press.

MPA II PVA - Pre catalyzed one part formula for cold set, hot press or RF curing. Color - Tan. Assembly time up to 15 minutes. Clamp time 30-45 minutes.

MPA Veneer PVA - For veneering when faster production time is required. Reduced bleed-through & checking. Color - Tan. Assembly time 20 minutes. Cold press time 45 - 60 minutes.

MPA Slow PVA - Moderate set time, very high heat resistance good assembly time. Color - Yellow. Assembly time 30 minutes. Cold press time 1-2 hours.

MPA Fast PVA - Fast set, high heat resistance, ideal for doweling & case goods. Assembly time 10 minutes. Cold press time 20-30 minutes.

MPA Dark PVA - Good heat resistance, excellent for edge gluing face gluing of softwood and hardwoods. Color - Dark Brown. Assembly time 15 minutes. Cold Press time 30-45 minutes.

RESORSINOL Glue - Good for gluing veneer in structural applications or gluing to dissimilar materials.

OPTIMUM PRESSURE FOR VENEERING:

25 to 200+ psi - Mechanical or Hydraulic Press

10 to 13 psi with Vacuum Bag

A FEW POINTERS WHILE VENEERING:

Lay up your veneer while the substrate (MDF?) is still flat - like making your own BLUEPRINTED sheet goods. Pour some glue in a tray. Roll on with a hard rubber roller - a nice even & THIN glue line.

Never apply glue to the veneer itself - only to the substrate. Allow the glue to flash for about 15 or 20 minutes if using Urea Resin in a cold press, so it will be slightly tacky. Use minimum 3/4" MDF cauls made just proud of your substrate.

Clamps should cover square area every 3" to 4" or 3" to 6" with a thicker caul. Always apply pressure from the center out in a spiral pattern (Like torqueing a cylinder head on an engine). You should have no rippling. If you are getting squeeze out on your panels, chances are you are applying too much glue which causes rippling.

I would also suggest you glue the reverse side of your substrate with a counter balance veneer (backer veneer) even if the back side will never be seen. This should be done at the same time as gluing your face - especially in a hot press. This evens out stress on your outer skin and helps prevent future problems with your finish...

REMEMBER: Never apply glue directly to the veneer. Apply a uniform thin coat to the substrate only. Use the proper glue applicator for the glue you are using, or on smaller projects use a tray & small 3"+ hard rubber roller. Use MDF as a substrate whenever possible and always make it a point to veneer both sides of the substrate for balanced construction...

RESOURCES: Veneer Glues and Veneering Equipment:

Veneer Systems

John Ersing & John VanBrussel

johnvanbrus@veneersystems.com

1-800-825-0840

http://www.veneersystems.com/