Dissolving various glues

[Magnus Nedregard]

How often have you cursed those people who put non-traditional glues in instruments? Well, one must be pragmatic and cursing won't open any cracks. (I've experimented that thoroughly).

I guess we all come across occasional seams and cracks with the "wrong" glue present, and that's when I feel rather helpless. Frankly I know very little about how to deal with this. So what have you got in your arsenal in these cases, why don't we try to list up solvents for all those glues... if they exist at all.

I've found that those horribly gummy white glues soften a little bit treated with acetic acid, but you still have to work mechanically to get rid of it. Some harder glues snap rather easily if gently heated with an alcohol flame, but that's about all I've got. (And yes, I've got a 50 cm soundpost crack in rather nice cello back here, that has been glued with an unidentified super-strong glue )

[FiddleDoug]

I'm not an expert at this, but I'll add to the discussion. The carpenters glues, like Titebond, should soften with acetic acid (vinegar) and time. Cyanoacrylates will fall apart with heat, or dissolve with debonder solvents. Casein glues might be the toughest. I don't know anything to soften those.

[Matthias Lange]

Cyanoacrylate and PVAC-Glues can be dissolved with acetone. Unfortunally aceton dissolves varnish too.

Matthias

[~ Ben Conover]

Magnus, I know more now than I did 1 minute ago, thanks.

On the Bros. Guastalla I'm restoring the linings have been glued in with some kind of white substance, Casein prhaps ?

Previous repairs and set up were done with strong hide glue, made it very hard to open the box.

[fiddlecollector]

The often used solvent for epoxy is dimethylformamide.never tried it or dont know how it will affect varnish etc..Its available from kremer,probably works on pva as well.It does carry hazards though like most organic solvents.

[Magnus Nedregard]

I'm already a little wiser. Ben, most casein glues I've seen don't look white when dry. It looks rather like hide glue actually, and is very hard, not gummy at all. Casein glue can "snap" since it is quite brittle, I wonder if pure alcohol could make it even more brittle, like we do with hide glue?

[~ Ben Conover]

Thanks, that leaves me wondering what glue is in this Guastalla.

[Bruce Carlson]

Thanks, that leaves me wondering what glue is in this Guastalla.

A lot of furniture restorers and woodworkers in Italy add some white pigment to their glue so they don't get black lines on the bad glue joints ... It is not uncommon.

Bruce

[Stephen Shepherd]

According to Merck's Index, Casein glue is listed as: Sol.: Alkalies; insol. W., A., E.

[Magnus Nedregard]

So to summarize; what we've got is:

Cyanoacrylates: Acetone

Carpenter glues: Acetic acid

Epoxies: Dimethylformamide

Casein: nasty caustic stuff

For the record, my old back-crack there came apart nicely with a combination of careful application of acetone from the inside and a short blast of heat form the spirit lamp. Perhaps it was superglue?

I would like to hear what some museum folks might know about casein glue, I guess they encounter it more often than us.

[Roman Malamant]

Magnus,

Henry Strobel said he use Loctite X-NMS Solvent in a 2 oz. (59 ml) brush top bottle to dissolve CA glue (it was discussed on another forum I think). He said that it is less aggressive than acetone to varnishes he tested. Henry still advices to use it with caution as there might be some varnishes that could get damaged more easily. I personally didn't try this solvent.

[fiddlecollector]

So to summarize; what we've got is:

Cyanoacrylates: Acetone

Carpenter glues: Acetic acid

Epoxies: Dimethylformamide

Casein: nasty caustic stuff

For the record, my old back-crack there came apart nicely with a combination of careful application of acetone from the inside and a short blast of heat form the spirit lamp. Perhaps it was superglue?

I would like to hear what some museum folks might know about casein glue, I guess they encounter it more often than us.

Morpholine can be used as one of the only solvents for dried casein(its an aromatic amine with an ether group),it also removes and emulsifys shellac. Its boiling point is around 125 degrees C but has around the same volatility as water so can be mixed/diluted effectively without evaporating quickly like many solvents.

The only downside is its supposedly HIGHLY TOXIC, and shouldnt be used outside a fume hood.(According to one safety data sheet,) other sources say its fine in diluted form,as the boiling point is high, inhalation is negligable unless heated.Its used in waxing fruit ,cosmetics etc...

Ive seen some products with 5% morpholine wth no safety warnings .So dont know what to believe.

It is used by some conservation departments to remove casein.

[Magnus Nedregard]

Thanks for that tip Roman. Here's an interesting quote about morpholine from its Wikipedia article:

"Morpholine is used as a chemical emulsifier in the process of waxing fruit. Naturally, fruits make waxes to protect against insects and fungal contamination, but this can be lost by means of the food processing companies when they clean the fruit. As a result, an extremely small amount of new wax is applied. Morpholine is used as an aid by the dissolution and emulsifing of shellac, which is used as a wax for fruit coating."

So don't eat your orange peal guys!

[Roman Malamant]

So don't eat your orange peal guys!

Good to know! Now I got an excuse to ask my wife not to put orange or lemon peals and shaves in cakes. I don't like that taste!