| I have been asked several times how properly prepare
hide glue. Hide glue is the standard glue that is used by violin
makers, and is prized for its organic nature and ability to be dissolved
to remove a plate or other part of a violin and perform necessary
These very qualities are responsible for many of the small violin
repairs - humidity and dryness can weaken the glue joints, making
re-gluing of loose joints necessary. However, on the same note,
the strength of a good hide glue joint is almost unmatched - it
can easily be stronger than the wood itself. Spreading a thin film
of hide glue on a plate of glass will damage the glass - often times
breaking it (I have had clear glass baby food jars and ceramic pots
broken while it is shrinking during drying).
Hide glue is available in a powder, granular or flake form. It needs
to be mixed with water to dissolve.
Below is my glue set-up. This is working equipment - so is well
To heat the water for the glue I use a rather ordinary laboratory
hot-plate with a dial heat adjustment on the front. An alcohol
lamp, old clothes iron (upside-down), or other heat source could
Hide glue is made in a double-boiler to prevent the glue from
over heating or becoming scorched on the bottom. Half of a soup
can or other metal container could be suitable. I use a copper
glue pot from an alcohol-lamp heated glue pot assembly that I
purchased some time ago.
This is the outer jacket that holds the (hot) water. The glue
container is placed inside this.
This is the copper pot that I use to actually hold the glue. Again,
it is from the pot that I purchased. It is placed inside the water
jacket (image 3) so that it is suspended in the (hot) water.
I have also used baby food jars, held with a simple wire frame
to keep it from tipping. A tin can smaller than the water jacket
would also be suitable.
The glue pot holds about 4 ounces. I usually start with about
2 ounces of cold water, and put one common teaspoon of dry glue
into this. The glue should be fully dissolved while the water
The glue should be heated to about 70 C, or 165 F. I must admit
that I don't use a thermometer. The water in the jacket should
be quite hot, but not near boiling point.
When the glue is ready, there should be a slight skin forming
on the glue - but beyond this the glue will become too thick rather
quickly. At this point I usually put a couple of teaspoons of
water into the glue. Between the fingers it should feel oily,
but not thick. If it feels watery, it is likely too thin.
If you refer to Image 1 (above), you will see a selection of tools
that I use for applying the glue. A 1" brush (dollar store
variety should be adequate) is great for applying glue to fingerboards,
nuts, saddles, and other flat surfaces requiring glue.
I use a knife (the black handled artist's knife with the aluminum
blade is one of my favourites) to apply the glue into an open
edge seam (there is no way of getting a brush into these tight
cervices). Be careful to leave the metal knife blade in the hot
glue for at least a few seconds before using it, or it can quickly
cool and gel the glue on the knife. Once hide glue has gelled,
it must not be clamed, as it will create a "cold joint"
that will fail to obtain maximum strength.
For gluing cracks on the top or back of an instrument, rub the
glue into the crack (this can be done with a brush or clean fingers)
until it starts to come through the other side. Have appropriate
clamps ready, so that it can be clamped while the glue is still
warm and thin.
Make sure that all glue is wiped off of varnish, and washed from
unprotected wood. Glue or glue-water can damage varnish that it
is allowed to dry on. Unvarnished wood that absorbs glue or glue
water will not accept stain or stained ground varnish as well
as the surrounding wood, so will leave light spots under the varnish!
Hide glue is available from http://www.violins.ca/supplies/hide_glue.html
I recommend the medium strength (315 gram strength) glue. All
strengths of hide glue are capable of making a joint stronger
than the wood. The major differences in the glue is the working
time. The strong glue (380 gram) tacks faster, and the weaker
glue (195 gram) gives more working time. In my opinion, the 315
gram gives the best of both worlds, and IS rated stronger than
the weak one.
An excellent plastic glue pot, with 2 sections (one for glue,
one for hot water) can be found at www.violins.ca/tools/tools_herdim.html
Dry hide glue can last indefinitely. Once the glue has been dissolved
in water, however, it does not last long. In the summer (here
in SW Ontario, Canada) when it is hot and humid, the glue will
typically only last one day. The second day it starts to show
very small pits in the surface (mould). By the third day it can
be green and furry. In the cooler, winter weather it will usually
last several days easily, but I usually make new glue each time
to be safe (it is a small investment).
I have heard that refrigerating the glue can extend its useful
life. This is probably true, though I have never found it necessary.
Ready-to-use hide glue can be obtained. It contains a preservative
(formaldehyde?) that keeps it useful for up to several months.
I have, however, heard of one maker who used it exclusively on
his first several instruments with disastrous results - so I would
not recommend its use, even if there are those who have good experience
with it. Don't say I didn't warn you!
Below is an article about hide glue that I have had around for
a while, that may touch on some points that I have overlooked: