Updated 8.23.2012 – see below
I came across this at Robertsons and Sons Violins where they have not used any other animal glue for many years.
It is a good quality animal glue, liquid at room temperature and consequently has a long working time of several minutes compared to the working time of less than a minute – under optimal conditions – for hot animal glues. It has a lower gram – strength rating than hide glues but I have found that gram – strength measurement doesn’t necessarily describe the strength of the joint prepared with any given glue. I base my opinion on making the joint and observing how it holds up as I continue work on the instrument or repair.
Pros. I tried it for a month and found it very easy to work with. I kept it in small squeeze bottles, one for each of three dilutions for different applications – major joints, cracks, glue sizing etc. The long set up time is a joy, it cleans up well with water during application and removes easily after drying so would meet the non-damaging requirement for restoration work.
Cons. Unfortunately I also found that using it made my eyes run and where I got even a little of it on my finger tips the skin got very rough and even peeled. Checking Kremer’s fish glue msds they describe it as “not hazardous” but list phenol among the ingredients. Since Kremer says that no gel inhibitors are used in the product I assume that the phenol is a preservative and in fact the shelf life of several years is remarkable for something that is almost pure protein and should be good food for somebody. The msds for phenol describes that chemical as “extremely hazardous” so, regretfully I decided to limit it’s use and to applications where it gave me a great advantage over traditional hide and bone glues.
I will look into mixing up my own fish glue minus the phenol, if it has all the advantages of the premixed product minus the extended shelf life it would be very worthwhile.
The combination of its viscosity and non-gelling nature make it very good for center joints and neck joints where the a lot of glue can be applied and the excess has time to squeeze out during clamping, yet enough remains to avoid glue-starving the joint. I would also consider using it for large reinforcing patches where normally you have to use thinner glue on larger patches because of the decreased p.s.i. developed when clamping larger areas. It might be possible to heavily glue size each surface and simply re-wet the glue prior to clamping. I haven’t tried this yet.
Because it doesn’t set by gelling, work can be successfully done at lower room temperatures and without warming the work parts prior to gluing – much more convenient. Wear gloves.
Better fish glue
I called Milligan and Higgins to ask about Fish glue and discovered that they manufacture the Kremer fish glue that I wrote up before. It’s made in Canada, shipped to Germany and distributed in the US via Kremer, New York.
When I asked for a fish glue without Phenol I was recommended this “Gelatin from cold water fish skin” which has a food grade preservative. I bought some from Sigma Aldrich ( cat # G7765) they also make a dry form which I was told would not be as strong. I’ve ordered some of the dry but haven’t tried it yet. The wet, pre-mixed version is pretty spendy at $110/ liter but it works well and doesn’t give me the skin reaction that the Kremer product did. For the convenience and improved workability I think it’s worth the cost. There is way less wastage than with regular glue because it doesn’t go bad and because of the greater viscosity there is less squeeze out.