Don Stephan
Posts: 825
Joined: 2003-07-18
Location: Cincinnati, Ohio
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A gauge for glue thickness that has worked for me is after spreading an even layer, drag a finger through the glue while pressing down lightly on the surface. If a slight ridge of glue forms on each side of the finger the glue thickness should be about right. I use a black foam roller pad to spread the urea formaldehyde UH), and another indicator of glue thickness is whether little ridges form on the glue surface behind the roller, and how quickly they lay back down. If the glue is too thick the ridges are more pronounced and slower to lay back down.
When I first started using UH, I made several test pressings (it was also my first time working with veneer), carefully weighing how much glue I started with, how much was left on tools and equipment, and then by subtracting how much I was spreading on the substrate per square foot. I even compared what seemed to be the ideal amount per square foot separately for MDF and baltic birch substrates. This also helps when planning a project, to see if I need to order more. Occasionally I have to add a bit more, but the effort gets me in the ballpark, and I always watch behind the roller.
Instead of setting the furnace back, the evening before a pressing I'll bump the thermostat to 70°F, set up the bag, platen, vacuum pump, and electric blanket, and make sure the bag and pump hold vacuum and the blanket works. The next morning, first think I'll turn on the blanket to begin warming the platen.
One added point, I only roll UF on one of the two surfaces, the substrate, or if I'm making a two ply to be glued to the substrate the next day to the upper surface of the backer ply. I never apply UF to the glue side of the show veneer.
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