Dan,
in order to exchange recipes and techniques, especially in the
international-multibackground world as we are living in, it is important to
use the proper terms for the stuff we are talking about. Thesaurii are
therefore very important. The stuff that is called fish glue by a lot of
people is also called isinglass or saliansky glue, these terms can cause
confusion when they are used separated from each other. Therefore in my
opinion a glue that is made of fish parts is not necessarily to be called
fish glue but something like *glue made of fish*.
The reason for this is that the way the glue is made is different
and the product made is different: the swimming bladder of the sturgeon
family contains no fats, it gives a very pure type of gelatin that, when
extracted at not too high temperatures, will be almost glasslike and is
therefore suited to be used where the colour of the glue is of importance
(did you know it will dissolve in alcohol!!! - new possibilities). When
other parts of the fish are used fats present in the fish will be extracted
also, this changes the properties of the glue: more flexible, colour etc.
Also when talking about gelatins and glues (and they are not the same
thing) derived from other animals than fish you can stumble across terms
like *bone glue, hide glue, rabbit glue* and the like. This because the
glues thus named are made of different parts of the animal body:
bone glue bones, sometimes hoofs best quality- almost only collagen
hide glue hides and cut-offs contains fat
rabbit glue hides from rabbit, hare etc, less coloured
The hides, hoofs and bones are cut/broken in smaller pieces and
then soaked in limewater and washed after about 24 hours. Extraction in
warm water (double boiler) follows, just like making a bouillon, the
extraction temperature is important, the lesser qualities are extracted at
higher temperatures. For bone glue 60 C is sufficient, for hide and hoof
glues start at 65 C. Too much fat present in the glue (= not pure gelatin)
will cause problems in use: it will not stick! add some chalk. Also when a
glue does not spread well and tends to form drops on the surface add two
drops of oxgall. Hope to have given you a good recipe for home brewn fish
soup.
yours
Bas van Velzen
Jonge Eland papierrestauratie
eland@knoware.nl
t +31 20 623 79 89
f +31 20 627 32 23
VeRes (Dutch Association of Professional Restorers)
postbus 11503
1001 GM Amsterdam
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