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Has anybody successfully used Friendly Plastic for anything associated with building guitars? I bought some a long time ago, but never got around to using it. I pulled it out today to experiment with molding some gluing cauls for an odd shaped bridge. I watched a blooper reel from Robbie O’Brien where he was having trouble with the stuff. Oh, that’s amusing. I’ll be careful to watch for the stickiness.

OMG!!! This stuff is MADDENING. While molten, it is runny and sticks to everything. EVERYTHING. Once it cools, it lets go, so I guess that’s something. But it is also kind of brittle once it cools. I don’t see how this stuff can work for gluing cauls.

If I ever want to do something like this again, I will use epoxy or Bondo. This Friendly Plastic was a bust for me.

Has anybody used it successfully for anything?

I tried to make a caul for gluing the reinforcement patch for a side sound hole.

My kid now uses it to make toys if that tells you anything.


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I use a layer of saran wrap between the bridge and plastic to keep the wood dry and to be sure it won't stick. But maybe it's not necessary after all

Anyway, set the bridge on the bench, saran wrap over the bridge, molten plastic on that, and smush it down with something flat. After it cools, peel the saran wrap off and saw/chisel the excess plastic from around the bridge imprint so you have a nicely fitted caul that only contacts the bridge and not the soundboard. Use a flat block of wood to support it when clamping. The plastic is only to fit it to the bridge. Not stiff enough to use as a caul by itself.

I've used it for a mold to cut inlay channels with my pantograph. It hardens well enough. You have to remember to spray the inlay you use with Pam or dip in olive oil or something so the inlay won't stick.

I have used it for sound port patches too and it worked rather well. Saran wrap for sure.

Sticking to the workpiece was not the issue; I had plastic wrap over that. My problem was that getting the Friendly Plastic from the water pot to the workpiece was like have a fistful of drippy snot that wanted to clutch onto everything but the plastic wrap over the workpiece. You guys are obviously more tolerant of the mess than I am. More power to you. I'm headed in a different direction.

Let it cool down a bit more before you pick it up.

I don't use a water pot. Try using your microwave. It doesn't take long, so don't "over cook" it.

It works great for a 90 degree stress relief on your laptop power connector.

i use Milliput epoxy putty for cauls , great stuff.

I use it all the time for making clamp cauls for arched tops, bridge cauls, etc. and also for drawing out the dome of arched top instruments. To keep it from sticking to my hands I use "liquid gloves" by Rath's. Rath's PR 88. This stuff is amazing. I also use Rath's PR 88 when I am working with woods which I am allergic (cocobolo and pau ferro).

https://www.amazon.com/Pr-88-Hand-Prote ... B0058EDHQ2

Also, like Dennis said, let it cool down some. I dump out all the water and let it sit for 2-3 minutes before handling.

Bondo makes great cauls too.