Isinglass Glue

[superdav95]

Hey all not sure where to put this so I’ll try here. 

I acquired some fresh sturgeon bladders from a sturgeon farm up here in Canada.  I got this frozen and had it shipped to me from the east coast.  It ended up being about 4pounds fresh weight.  I cleaned them up and cut off and trimmed all the extra little bits.  They are huge bladders!  Should give me a lifetime supply of glue for my next build which will be a full fledged horn bow.  I’ll see how this glue turns out before I use it on a bow with some tests.  I’ve heard good things about sturgeon bladder glue for horn bows instead of hide glue.  I Read adams book and he suggests he used a combination of both hide glue and bladder glue.  My impression from the book was that hide glue on the wood form was fine but that it was recommended to use sturgeon bladder glue for the horn glue up.  Here are some pics of the bladders I scored.  Got them drying right now.  Anyone had experience making this glue that can give me some tips on temp to double boil and for how long.  Let me know.

Cheers

[bownarra]

Cut it up into small pieces first.
Then heat at upto 65 deg Celsius for 8 hours.
Strain, then reduce what you have left (below 65 degs) until thicker. Be very careful not to overheat at this point.
Then pour onto a silicone baking tray until 1/4" deep.
Allow to gel then cut into small squares.
Either freeze as is for 'instant' use or dry until hard as rock in front of a fan (no hotter than 20 degs).

then send it to me

what Adam was talking about is to add bladder glue because it extends gel time considerably. This is vitally important when you are gluing the horn as this step takes time and you cannot have the glue gelling before you get it clamped up.
fish bladder glue also resists moisture ingress very , very well and is a very strong glue.

[BowEd]

Basically the same process as making hide and sinew glue.The reason for smaller pieces is that it increases surface area to extract the glue from.
http://www.primitivearcher.com/smf/index.php/topic,67763.0.html

[superdav95]

Awesome fellas thanks for the info.   I’ll do that and try some tests for my own piece of mind.  I ended up with five good pieces that dried up on the dehydrator overnight at the lowest setting.  My next question is should I do up all of this stuff now or just a few pieces at a time?  I’m not sure how much glue each piece yields.  The dry weight of each piece varies between about 450-875grams each.  Is there a rough estimate as to dry weight of bladders to volume of water???   Can’t seem to find a lot of info on making this stuff.  Ed, Would it be similar to your 1 pound of rawhide yielding  2.5ounces of glue?  I started with approx 4 lbs of sturgeon bladder. 

Thanks guys

[bownarra]

You didn't need to dry them. You now need to rehydrate them! Yes do them all. Just use enough water to cover your pieces. Of course it will steam so you need to keep an eye on the water level.
Yield is very high with bladders.

[superdav95]

You didn't need to dry them. You now need to rehydrate them! Yes do them all. Just use enough water to cover your pieces. Of course it will steam so you need to keep an eye on the water level.
Yield is very high with bladders.

Ok that’s good to know for my next batch.  I’ve cut them all up into small strips and covered with water in double boiler.  I’ve got my laser thermometer at the ready to keep an eye on it.  In my earlier post I forgot to put decimals on the weights in grams.  It should read 45.0-87.5grams per piece.  All in all I have a total of about 302.5 grams of fully dried bladder from 5 large bladders after trimming off extra bits.  I’ll now rehydrate for a while until soft then start the cook.  My thinking in drying these was partly because I didn’t know how much of this to use or how much of it I would need now and was thinking it was a convenient way to store it dried.  It makes sense though to do it up all at once now that I think about it and then dry it as glue cubes instead.  Thanks for the tip bownarra.   

[superdav95]

So just a quick question to anyone interested in the sturgeon bladder glue.  Is it absolutely necessary for me to remove the inner membrane to use for my glue or just cook the whole thing.  It’s been pointed out to me that some have scraped off the inner membrane first before cooking for the glue and not to use the outer layer.  Is this necessary for our purpose in bows (horn bows ) or is this removal of inner membrane for other uses specific to paintings and musical instruments and the like.  My thoughts on this are that if the fibrous inner membrane dissolves during the cook and the whole mess is strained anyway should it matter???   Let me know your thoughts and or experience with this.   Thanks

Cheers

[bownarra]

Yes don't be too fussy...bung it all in the pot!

[superdav95]

Thanks.  I’ll try not to sweat it.  I’m a little ocd .  I followed the cook recommendation closely and kept it low.  Took all of 10 hours. Next time I won’t dry them first.  I then cooked it down by at least half and ended up with a light syrup consistency.  Very light colour on this stuff.  I poured into baking sheets and set it in cold garage for 10 mins and it gelled up.  Not sure how long it actually took to gel in the cool garage and not sure if that’s a good sign or not to gel that quickly.  I cut it up into little fishy Jell-O shot size squares!  Got me 4 full trays.  I’ll freeze a little of this for some tests as well but will dry up most of it.  Thanks guys for the input. 

[superdav95]

Got it all dried up.  This stuff is rock hard! 

[BowEd]

That came out great for you.Nice light color.Your right it's unbelievably hard when it dries.Reducing it into smaller pieces will help to get it dissolved quicker in water for use.
Store it sealed where bugs can't get it.

[superdav95]

Thanks Ed.  Will do. 

[bownarra]

It is useful to stroe some frozen at this point before drying it all. The frozen stuff can be used straight away. The dried needs to be soaked in cold water until it rehydrates...which can be quite a while with bladder glue - it resists moisture better than any other collagen based glue.
The gel time is good.
A strong gel is your best indicator of strength.
The stiffness of the glue is a key factor in a true hornbow. It provides a transisitional 'layer' between the core and horn / core and sinew. One of the main reason s to do mismatching grooves on the core/horn joint. The grooves are filled with glue and the glues stiffness is inbetween the horn (low bend resistance) and the wood (stiffest thing in a composite).

[superdav95]

Bownarra. 

I did freeze a bit prior to drying.  It took few days to dry fully here as we are pretty humid as well in Ontario. What I found interesting was that upon examining these little dried bits further they hardened up well but still strangely flexibly on really thin sections. I’m sure they will break if I were to keep bending them back and forth eventually but seems pretty good indicator that maybe it will have some flexibility anyway.  We shall see when I run some tests on to be sure.  It’s gelled fairly quick on me even in between stirs on the spoon I noticed it gelling up.  I left the small piece of bamboo I initially used to stir on a small saucer on the counter and it stuck to the plate quite well.  Had to pry it off!  Dried up clear and hard.  That’s what we want I guess.  Thanks again for the info on how to make the glue. 

Cheers.

Dave