How to remove bridge glued on with contact cement?

September 29, 2016 at 11:24 PM · Bridge glued on with contact cement. Student violin.

What technique would you use to get this off?

Another question. I removed the nut for a fingerboard dressing, but it didn't come off easy. After applying some heat to it, it still wasn't coming off, and then after giving it a good hit it came off in two pieces. It took me about 10-15 min. with a chisel to get the small piece that was still attached to the fingerboard and base off. I was thinking they Krazy glued it. What kind of glue is used on this part at times? Anyway, I installed the new nut with a small amount of hide glue just on the fingerboard side; it will come off easy next time.

Replies (15)

September 30, 2016 at 12:57 AM · It's not just bridges that get "glued" on with epoxy resins or similar, but cracks or open seams that get "repaired" with such resins, fingerboards firmly attached in like manner, and not forgetting a top plate that has started to part company from the rib being stuck back with pva glue. I once saw a folk fiddle in which its enterprising owner had dealt with a soundpost that was always falling over by the simple expedient of nailing it in place with a fine nail through the back plate. All these every professional repairer's nightmare!

I suppose how these situations are handled depends on the intrinsic value of the violin and how much the owner (who may not have been responsible for the situation in the first place) is prepared to pay.

In the case of a glued-on bridge on a violin in, shall we say, the lower price range, you can be reasonably sure that it is unlikely to fall over or move, but could still be modified (cut lower, for example) to a certain extent in situ if necessary, so not necessarily the worst scenario in such a violin.

Now for the professional comments.

September 30, 2016 at 03:53 AM · Contact cement remains somewhat rubbery even after fully drying. It's really not very strong, and you should be able to remove the bridge if that's indeed what's holding it.

Then the question becomes "how do I get the contact cement residue off?" On a student violin I would try a product called "Bestine" rubber cement thinner. I often use it to remove residual adhesive from stuck on labels, and it's never damaged any surface or material that I've used it on. But admittedly I've never used it on a violin, so if you decide to, go slowly and carefully.

September 30, 2016 at 03:55 AM · How about a sledgehammer?

September 30, 2016 at 04:26 AM · Bestine is heptane (mineral spirits). Rubber cement usually softens a little more with toluene. You'd want to be cautious about testing an out-of-the-way bit of the instrument's varnish first. Toluene is more likely to damage varnish than heptane, that's my guess.

September 30, 2016 at 08:02 AM · All of these products would probably be solvents for the varnish of the violin, SO DON"T USE THEM ON THE VIOLIN.

September 30, 2016 at 10:40 AM · We need an industrial chemist to advise us as to what chemical can dissolve the contact cement but leave the violin varnish untouched. If this is a cheap violin then it is probably not 'real' violin varnish.

September 30, 2016 at 11:25 AM · When the OP says "contact cement" they are quite probably referring to super glue.

September 30, 2016 at 11:36 AM · www.supergluecorp.com/removingsuperglue.html advises that the one substance that will remove superglue is acetone, a constituent of nail polish. But go slowly and carefully, working at almost a microscopic level with fine tools, if it's superglue that's holding that bridge in place.

September 30, 2016 at 12:57 PM · Now seriously, someone here suggested long ago to cut off the bridge and trim the feet down to the level of the glue; then slowly work on the glue residue only.

September 30, 2016 at 01:17 PM · Acetone is a known solvent for virtually any violin varnish, so no don't try acetone.

September 30, 2016 at 03:43 PM · I agree with Lyndon -- I would NOT use acetone. The problem is that good solvents for the glue will also be good solvents for varnish. My assertion that heptane is less likely to adversely affect varnish is based on my knowledge as a chemist. But it's still only a guess, and you've have to verify that empirically using a small varnish sample in an out-of-the-way place.

(Unfortunately, I'm not an "industrial" chemist so therefore I don't quite meet Brian Kelly's criterion for sufficient expertise. But I do know enough to assert that the first plan of attack for such problems is not always chemical.)

If the adhesive is cyanoacrylate superglue, the adhesion between the glue and the varnish is likely stronger than the adhesion between the varnish and the violin. In that case you are left with mechanical solutions such as cutting (very sharp knife) or grinding/filing/sanding.

Rocky has the right idea.

September 30, 2016 at 04:02 PM · Rocky, that was probably me, and that's the way I'd do it on an instrument of high value.

Paul, I agree that mineral spirits is much less likely to damage varnish than acetone. Mineral spirits may not dissolve contact cement, but with enough patience, may soften it enough that the bridge can be removed without pulling away varnish or underlying wood.

September 30, 2016 at 04:09 PM · In this case I don't know why anyone would care about the varnish.

September 30, 2016 at 04:19 PM · David, yes, it was you and I do take any credits.

I wonder if the top plate is thick enough, and the instrument not too expensive, why not experiment with reverse graduation of the top?

Remove the bridge, remove the glue and thin the plate up to 2mm.

If it breaks, you may use it to practice sound post patch, etc.

Crazy enough to suggest?

September 30, 2016 at 06:06 PM · I did an internet search this morning and found David's post.

I also glued a 1/2" x 1/2" piece of wood to a larger unvarnished piece of wood. Several hours later I took a clothes iron and heated the small piece of wood and the glue began to loosen and I was able to remove the piece quite easily.

Thank's the ideas


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