Raw Veneer
I have been working with large sheet raw veneers for many years. Many of my speaker projects are curved -- so clamping would be problematic. I use premium grade Le Page's contact cement. (NOT WATRER BASED) Here is the method I use:
1) Cut your veneer sheets 2 inches larger (on both dimensions) than the area they are required to cover.
2) If the veneer is heavily figured (burl, knotty or birds-eye), you MUST use veneer softener. Mix up this stuff according to the manufacturers instructions in a spray bottle. Spray both sides of the veneers -- let it sit until the veneer becomes pliable. GENTLY attempt to flatten the veneer. If you hear any "crackly" sound STOP -- this is the veneer cracking. Apply more softener and wait (maybe an hour). Repeat until the veneer is pliable.
3) Using 3/4" MDF (cut at least 2" larger then the veneer on both dimensions) as a press, lay down 2 sheets of brown kraft paper the same size or bigger than the MDF. Lay down the wet veneer sheet on the brown kraft paper sheet.
4) Cover the wet veneer with another 2 sheets of brown kraft paper. Then cover the brown Kraft paper with the second piece of 3/4" MDF. Depending upon the temperature and humidity in your shop, the drying time could take up to 24 hrs.
5) If you are applying then veneer to curved items you should not let the veneer COMPLETELY dry -- it should remain somewhat moist and flexible. If you are applying it to flat surfaces dry it out completely.
6) On an other piece of MDF, lay down the veneer with side you want to glue facing up. Use masking tape to hold down the corners. Using Le Pages premium contact cement and Le Pages contact cement thinner (use only this stuff to reduce the cement viscosity) make a 50% mix of cement and thinner. Put this in an air powered paint sprayer. (A cheap Chinese model will do nicely here).
7) Working in a WELL VENTILATED AREA and wearing a CHEMICAL RESPIRATOR (s simple dust mask WONT DO) apply a coat of thinned contact cement with the sprayer. Let it dry completely -- the must be NO TACKINESS. Repeat this procedure until you have THREE COATS.
8) While you are spraying the veneer, you can spray the box (?) you want to cover.
9) When the veneer and box (one face) are covered with contact cement (3 coats) monitor their surface tackiness with your hand and a brown kraft paper drag test. If the cement coat looks dull, it is on the way to being dry. Test it with the palm of your hand. if it is not tacky, LIGHTLY drag a piece of brown kraft paper over the complete surface of the cement (both veneer and the box face). If it doesn't snag, you are ready to join the veneer with the box face.
10) Lay a piece of brown kraft paper on top of the box face that has the dried contact cement on it. Make sure the kraft paper is 4" bigger than the box face on both dimensions. Lay the veneer, glue face down on to the brown kraft paper.
11) Center the veneer as best you can in relation to the face of the box. With a helper, slowly SLIDE the brown Kraft paper OUT on one dimension do that about 1/2" of the veneer comes into contact with the box face, DO NOT PRESS DOWN..
12) Check alignment of the veneer and the box face -- make your minor adjustments NOW -- and make them correctly -- ONCE the the two faces with contact cement join they ARE NOT MOVABLE.
13) Once you are satisfied with the alignment rub the veneer with a LARGE ROLLER or a piece of 2 x 4 that has been sanded smooth.
14) Repeat the brown kraft paper incremental removal / press down process until the face has been completely veneered.
The reason most veneering projects with contact cement fail is due to the fact that most folks don't allow the cement to COMPLETELY DRY before joining the veneer to the substrate. Making this mistake will ensure bubbles, peeling and project failure. LET the contact cement DRY COMPLETELY (NO STICKINESS) before you join the veneer to the item you are covering.
Hope this helps...
