Looking for a good heat-releasable glue

[Jay McClellan]

I'm planning to make up some experimental rosettes, and since they are "experimental" I don't want to inlay them directly into a soundboard until I see how they come out. I came across a technique on the Internet a while ago, and I can't find the link now but the idea was to use super thin 1/64" plywood as a substrate glued to an MDF base, then assemble the rosette veneer onto the plywood. By using a heat-resistant glue for the veneer-to-plywood joint and a heat-releasable glue to hold the plywood to the base, gentle application of heat should release it easily (?). I could go with good old Titebond original for the releasable joint and CA or even epoxy for the veneer, but are there any better alternatives? Whatever is used under the plywood will remain on it to some degree even if I sand it down, and then I'll need to glue that surface into the spruce soundboard so it will need to be something that sticks to itself or to some other glue after being heat-released. Hide glue seems like a possibility but I don't think it releases all that well with heat alone (needs moisture too) and I'd rather avoid adding moisture. Any recommendations?

[ken cierp]

You can get very thin double sided that that will release easily with heat -- just a thought .
But I have to admit, I am not at all getting what you are trying to accomplish.

[Jay McClellan]

Thanks ken - here's what I'm trying to accomplish. I want to build up a rosette from various flat pieces of veneer, not strips laid on end where they could be glued around a form with CA and would be self-supporting, but flat pieces that need to be glued to some kind of substrate to hold together. Think traditional marquetry but with some CNC help. I could build the whole thing by gluing pieces directly into a soundboard channel as I'm sure many people do, but I want to build the rosette separately as it may take a few tries to get one that turns out right and I'd rather not ruin a good soundboard. I want to do some of the cutting on my CNC router, hence the need for a substrate like MDF that I can anchor securely yet I want to "peel" the thin ply and rosette veneer off when I'm done, which is why I'm thinking heat-releasable glue. The double-sided tape might do it although I wonder about residue that might interfere with a good glue joint. I'll be glad to post pics once I try this but at this point I'm just looking for ideas on how to hold a very thin layer very securely, and make it releasable without damage and without leaving any residue that would interfere with gluing it afterward.

[Kyle Barbour]

I do rosettes in a similar way. I use a plywood work board. Use some 3M spray adhesive to attach a sheet of paper to the board. I then assemble the rosette using CA glue on top of the paper. When I'm done I just use a thin metal spatula to work it from the paper. Here's a pic of one in progress to help with the explanation.

[Jay McClellan]

Thanks Kyle, that looks like what I need. Do you need to do anything to clean the paper off the back of the rosette after working it loose, or does it come off pretty clean? I think I need it to stick fairly well to the paper so the veneer doesn't come loose with the CNC router.

[Kyle Barbour]

I just do a careful cleanup with a scraper.

[ken cierp]

Another approach is to use a simple vacuum plate -- make a two layer pallet with an air space in between, drill a series of small holes in the circular pattern. You can even use a standard vacuum cleaner to generate the vacuum/suction, make sure you port the vacuum hose to let in some cooling air for the motor.