Hide Glue

[zinger]

At what temperature does hide glue become ruined?

[Thesquirrelslinger]

Do nto put it above 140 after you finish making it.
It will be ruined by 170 degrees or higher.

[zinger]

That's good. Someone said that it was ruined at anywhere above 150 and I thought that was a bit ridiculous.

Another question - how do I get the air bubbles out - is this possible? I would think that these would tend to compromise the backing but I'm not sure.

[Pat B]

If your hide glue is holding air bubbles I'd say it is too thick. I believe you want it to be the consistancy of pancake syrup.  Once it thins out a little the air bubbles should surface.

[zinger]

Yeah - that's probably it. 

[JW_Halverson]

The Bowyers Bible mentions that if you are in a hurry you can make hide glue rather quickly by boiling.  Something tells me this is a tad higher than the temps quoted in here as "ruining" it. 

If it loses 10% of it's strength from being slightly overheated for a short time, is it ruined?  If it is weakened 10% and still does it's job, will you even know it's ruined?

Test it.  Cut two 1x1 inch blocks of hardwood.  Sand them clean to make sure you remove any surface oils and glue them up.  Let the glue cure out for a good 72 hours.  Clamp one piece in a vice and clamp a pipe wrench on the other and slowly apply force until she lets go. 

Duplicate the test with a pair of blocks glued with TiteBond or some glue you have around the house.  Duplicate again using Knox unflavored gelatin. 

Make up your mind from there.

[mikekeswick]

The Bowyers Bible mentions that if you are in a hurry you can make hide glue rather quickly by boiling.  Something tells me this is a tad higher than the temps quoted in here as "ruining" it. 

If it loses 10% of it's strength from being slightly overheated for a short time, is it ruined?  If it is weakened 10% and still does it's job, will you even know it's ruined?

Test it.  Cut two 1x1 inch blocks of hardwood.  Sand them clean to make sure you remove any surface oils and glue them up.  Let the glue cure out for a good 72 hours.  Clamp one piece in a vice and clamp a pipe wrench on the other and slowly apply force until she lets go. 

I totally agree with testing things for yourself and have done so with different collagen glues. You are right that a 10% loss in strength won't really make a difference in most bow making applications. These glues are very very strong, strong enough that you have a bit of leeway when using them.
If you want to know what temperature these glues are weakened at then take a piece of sinew and put it in some water. Heat the water until the sinew turns into a spring.....thats your temperature 

[zinger]

That's an excellent idea for a test JW. Want to try that at some point. Will be interesting to see how pure gelatin stacks up against hide glue. I've recently mixed the two for a sizing on a hickory bow I'm working on. This brings me to another point, which is the application of a hide glue sizing, something that is all too easy to mess up. I quickly realized, after my first try, that you have only seconds to smooth things out. If you try to correct it after that things become an awful mess. What I do now is to use a large spoon, emptying it over around 12 inches or so of the bow and then I smooth it down with the underside of the spoon which seems to work very well. Then I do an overlap on the next section, which will create a bump but this can be easily removed by fine-grit sandpaper. Maybe next time I'll use a paintbrush and see how that works.

[zinger]

BTW, has anyone ever used gelatin/hide glue for limb laminations? I don't know how an the full length bow could be laminated all at once seeing how fast this stuff sets up.

[M-P]

Zinger,  I've done exactly that a couple of times in attempting to make replicas of Egyptian D bows.  I turned the heat in the shop up to ~ 100ºF and worked fast.  At high enough room temp the glue doesn't gel so  fast.   Ron

[zinger]

Sounds like your dedicated, MP. One thing I do is to use skim milk instead of water (makes it more water resistant) and I've realized that this makes for a slower set up time - not a whole lot, but enough to give you a little breathing room.

Another question I have is this: If you can get the glue to the right consistency at a temperature lower than 145, say 130 - 135, is that good enough so that you can go ahead and apply it? I mean is there something about 145-147 that makes it better?

[M-P]

Personal opinion is that the glue just has to be warm enough to be liquid.   After all "mouth glue" is applied at ~ 98.5ºF   Ron

[Pat B]

I bought a small crock pot from the thrift store for $5 and fill it half full of water and float a stainless steel pan in it with the liquid glue in the pan. This seems to hold the glue at the right temp.  If my work goes on for a long time I sometimes have to add a little water to the glue to thin it back down.

[4giveme]

zinger,
this link may be a help to you, as i too am going to try knox on my next bow.

http://www.primitivearcher.com/smf/index.php/topic,38992.0.html