Fishy Solution?

[Dave Yelverton]

I've recently had my attention drawn to Romanillos' advocacy of fish glue for guitar building. Apparently it has a good grab like HHG but a longer clamping time, dries to a similar hardness, has no creep, but can be a little harder to undo.

I'm keen to try this having been shown a source in Germany but I'd be more than pleased if anyone with experience of this would care to comment. Are there any jobs where you wouldn't trust this to hold? I'm thinking most specifically of gluing bridges. My workshop can be difficult to heat adequately and I find HHG gluing in winter a bit of a trial.

Dave

[Hesh Breakstone]

I've been using fish glue (FG) for several years now after being introduced to it by David Collins.  Like HHG it's a collagen glue and as you mentioned dries very hard and crystalline like HHG.  Additionally it is capable of successfully bonding surfaces with a very thin glue line also like HHG.

 

I use it where I might like to use HHG and where having a very hard, cured glue is advantageous but also where for one reason or another getting all the clamps in place quickly as is required with HHG is not possible for me at this time.  One example of where I use it is to glue on the plates.  Open time is very long, perhaps even an hour but don't quote me on this one and I would recommend reading what the manufacturers say (Norland).  I've also used FG successfully to reglue braces in my repair biz.  Again the long open time is the primary attraction as well as the very hard resulting cure.

 

It cleans up well but not as well as HHG in my opinion.  It's very sticky stuff and will get stringy not unlike cotton candy... if your clean-up routine is not adequate.  I use a bit of hot water and paper towels to clean up squeeze-out.

 

Where I would not use it is for applications where there will be a high moisture content.  FG requires some moisture to reverse as well as heat so for a guitar that is say going to a very humid climate I might not use FG at all.

 

It is great stuff though and bridges are a good application but only again if the instrument will not be exposed to high humidity.  As for shop temps required for cure I would consult Norland for that data - seems to me though that temps below 68-70F may be problematic as they can be with other glues as well.

 

[David Collins]

I've used fish glue for years, and it does very closely resemble hide glue in its cured properties - excellent heat resistance, creep resistance, dries very hard etc. Yes, it does have a very rapid tack, but also requires a much longer clamping time to full cure. 

 

I'm not sure where the source in Germany gets their glue from or where it's made, but isinglass aside (which is quite a different "fish glue" anyway), but the biggest supplier of fish glue I know of is Norland Products here in the US. Many companies repackage and resell their high tack fish glue under their own brand, but I've always bought directly from Norland. Of the few bad experiences I've heard of, all I know of have purchased their glue through resellers like Lee Valley. It's the same glue I'm sure, but it does have a shelf life (especially if stored unrefrigerated) and I worry that resellers may not move the product through fast enough to ensure that what you're getting is truly fresh. If it sits on an unrefrigerated stock shelf for a year or they don't rotate their stock properly, then you could certainly get some bad glue. 

 

For this reason I just buy straight from Norland. Last I ordered they had a minimum of $25 or $30, and a gallon pail of fish glue was about $5 less, but I've always just told them to bill me the minimum anyway and ship out 1 gallon. It's worth the extra few bucks in my opinion to make sure it's fresh. Of course if you're in Europe it may not be worth the shipping, but it may be worth inquiring with the dealer to make sure their glues are properly dated and stored. 

 

All that said, I don't use it for bridges anymore. While it is not nearly as humidity sensitive as some sources claim (all seem to trace back to the same reference the same rant from a player piano restorer's web site), it still is not an ideal glue for extreme high humidity environments. I have had two repairs come back, one bridge reglue and one top crack, which I repaired with fish glue and failed in less than a year, with both having been kept in very high humidity conditions. To be honest I'm not sure if hide glue would have held up much longer, as I certainly see a lot of old hide glue joints come apart after storage in Michigan basements as well, but I do believe fish glue to still be a bit less moisture resistant than traditional hide glue. 

 

More importantly though, once you've gotten used to a few basic tricks then gluing items like bridge joints should be so quick and simple that there's no reason not to use hide glue. Even if the shop is cold, 15-20 seconds in a microwave will warm up a bridge nicely, and a few moments with a heat gun can warm up the top enough to give ample working time. With your clamps and cauls ready and in place, the job should be quite simple even with the air temperature being moderately cool. Plus hide glue is much easier to clean up (fish glue can be extremely stringy and tacky, making clean up quite a chore), and cures much more quickly. 

 

I still use fish glue for jobs like brace repairs and some crack repairs which require a longer open time (or a hot room with hide glue), but for bridge joints I see no reason to choose fish glue over hot hide. 

[Gabriel Dehoyos]

 I had a classical guitar with a loose brace and it was fixed with fish glue that never set. Even after three months you could feel the glue was still tacky. Needless to say the brace came loose. It may have been a bad batch, old glue or high humidity? I have never tried it in my own repairs, HHG has served me well but I am open to the idea of fish glue. If it is good enough for Romanillos, then I better look into it more.

[Dave Yelverton]

This is the link I was kindly given by a helpful bloke on another forum:
http://kremer-pigmente.de/shopint/index.php?cat=0201&lang=ENG&product=63550
It seems to be a fish skin rather than an isinglass based glue and I know of a couple of UK luthiers who use it. They do seem to have reservations about its suitability for bridges, but given that the range of humidity/temperature is generally smaller in the UK than in the US, this may not be a particular problem. I think I may need to set up a comparison test however before I consider trying it. However it sounds exceptionally useful for the general guitar joinery so I shall definitely give it a whirl.
Thanks Hesh and David for giving me the benefit of your considered opinions and experience. It's always reassuring to know that I can always find expert advice on this site!

Regards
Dave

[Tom Mitchell]

I have two peghead repairs to do (my own guitars, I'm still a novice at this, and this will be my first attempt at this kind of repair).  One is a complete break (fairly clean, and lots of surface area) and one is an open crack with a few fractures trailing away along the grain.

 

Would fish glue be a good option?

[Eugen C]

I use epoxy glue for this

[David Collins]

It's not my first choice for headstock repairs. I typically use hide glue for open breaks that are fresh and clean with little or no missing wood, or epoxy for cases which have long been open and possibly oxidized or contaminated, or previously repaired, or missing any significant amount of wood. 

 

Fish glue may be suitable for the crack which is not fully open/separated, but the slightly lower humidity resistance leaves me just a bit less comfortable with it. I've repaired many in the past with fish glue and to the best of my knowledge none have failed, but today I opt for hide glue whenever feasible. 

[Hesh Breakstone]

And... if climate change (not getting political here intentionally..) ever comes to pass and the guitar has to be used as a boat paddle fish glue would also not be a good choice... ;)

[Dave Yelverton]

Shouldn't worry too much. If global warming upsets the world's water currents sufficiently it's likely to tip us into an already overdue Ice Age.. so how will all these glues compare at -40 degrees?

Speaking of which, I've looked through the technical data of the various animal glues on the Kremer site and I've come up against the term Bloomgram, which  I believe denotes glue strength, i.e. holding power( but correct me if you know better!)

I was interested to see that out of these, bone glue, two types of hide glue and rabbit-skin glue, the bone glue had the lowest Bloomgram value whilst the rabbit-skin seemed to have the highest. This rather reverses what I had always assumed! Does this mean that I should be using rabbit-skin glue if I want to achieve the greatest joint strength? If so, why don't I hear of more luthiers using it? Price doesn't seem to be a factor as Kremer puts out all these glues at the same price per kilo