Anatomy of a WurliTzer Theatre Pipe Organ
Much has been written and discussed about the glue you should use when rebuilding a pipe organ.
When talking about what should be used to attach leather to wood when it will be neccessary, at some
time hopefully in the distant future, for the work to be re-done
the general "expert" opinon seems to be "Thou shalt ONLY use hot hide glue" as was traditionally used.
Previously I have been guided to use white PVA glue, which has always been functional. It is easily
spread with a finger and easily rubs off the skin afterwards. Do not try that with hot glue. The problem
with PVA is that it is not very water soluable so that it is dificult to remove the next time, and we hope
there will be a next time but it will be so far in the future that it will be someone elses problem.
Hot Glue, being water soluable, makes it much easier to clean off old leather when it is time for
another rebuild. Simply dip the pneumatic into some water, or apply water to gaskets, until the glue softens.
The warmer the water the faster the glue softens but cold water will work if you are not in a greater
hurry than you should be.
If similar glue is to be used next time it is not neccessary to remove all the old glue but it is
preferrable to remove as much as possible.
PVA will actually soften in water as well. It just takes longer so the timber gets a longer soaking than
with the hot glue, which is not desirable. A short soak and a quick dry does not seem to have any
detrimental effect on the wood but the less time it is wet the better. It does take a long time and much
effort to remove most of the PVA from the timber. If PVA was to be used again it is again probably
not essential to get all the glue from the wood but if you want to return to a natural glue you must get
all the PVA off. This will require sanding down the wood to get to the glue that has penetrated the
pores of the timber. Many of the pneumatics were designed to be as close as possible to the minimun
size they needed to be to get the maximun speed from the action. Sanding down pneumatics may reduce the
dimensions just enough to prevent them from working properly. Sanding down gasket areas risks introducing
flaws in what should be a flat surface already.
Hot Glue does require extra effort to prepare the glue and some sort of heating pot to keep it at the
usable temperature. Once mixed it has a limited shelf life and should be refridgerated between uses to
prevent moulds. All this is little problem when it is being used continuously in reasonable quantities
but can be a problem when you are doing small amounts of work irregularly.
There is another option. Hi-Tack Fish Glue, available from the usual organ parts and leather suppliers.
Many of those who say Hot Glue is the only choice will, if pressed, also say the Fish Glue is also
acceptable. This comes as a ready to use liquid and is used cold, so it does not have the preparation requirements
of the Hot Glue, and is almost as easy to use as PVA but it is better to spread with a brush rather
than your finger. Hot Glue sets faster than Fish Glue which can be an advantage although the extra time
for the Fish Glue will probably not cause any problems in general work and may be an advantage for those
who need a little more time to get everything in place. Hot Glue is stronger than Fish Glue, but the
small difference should not be significant for most applications. Hot Glue smells more than Fish Glue,
so it depends on your preference. Fish Glue is just as water soluable as Hot Glue and as easy to remove.
Fish Glue is more expensive than Hot Glue, but you do not have the additional costs of prepartion and heating.
For low volume users the extra cost is probably not significant in the overall costs involved in
a pipe organ.
All other rubber, silicone or whatever glues should be avoided if you do not want the next person who
works on the instrument to have nasty thoughts about you, dead or alive.
I chose to use Fish Glue for this project.