Main Discussion Area > Bows
Hide glue gram strength
lebhuntfish:
Just go to the grocery store and buy a box of Knox unflavored gelatin. Mix a few packets in a little cold water and let it sit and get "jelly like".
I use a little crock pot with water in it, place a small stainless steel bowl on top of the water and put the gelatin in the stainless bowel and let is all warm up until it melts to a liquid. My crockpot never gets to hot so I just leave it on all of the time, it never gets to hot for my fingers so it's perfectly fine for the sinew. You don't need all that fancy stuff! Knox is nothing but finely ground hides and hooves. It's HIDE GLUE!
You don't have to make things harder than they are... )-w( :BB (SH)
Patrick
Eric Krewson:
I agree about the Knox, it has worked just fine for me. I don't think a small gram strength variation is going to matter considering how random applying sinew to the back of a bow really is. It is not like building with uniform bricks to make a wall, it is more like applying random lengths and pieces sinew to the back of your bow until you decide you have enough to do the job.
After I put on a couple of courses of sinew, I would cover the sinew with cling wrap while it was still wet and wrap it very tightly for the first couple of days so the back was smooth and even. After the sinew has cured to be hard, I sand the back to have a neat, even surface. I like this look better than having the strands showing.
Some folk enjoy delving into the complexities of bow making, my take has always been simplicity, make a bow, tiller it correctly and shoot it. Quite often it is the quality of the wood, not the bowyer that determines if a bow is just OK or a super performer.
superdav95:
I’ve tried the Knox gelitan with mixed results. I found it works ok with my hog gut backings just fine but on some of my more extreme designs I’ve had failures of delaminating for reasons unknown. It seemed very similar consistency and working time to my glue or other stir bought hide glue but lost faith in it and decided I’d start making my own glue with exclusively sinew scraps and haven’t looked back. It may have been a bad batch too but now I’m hesitant to use it. I’m sure it’s just in my head. A lot of guys use it so it must work. I’ve never had a failed sinew bow project with my glue yet that was fault of glue or sinew. It has been wood failures or design limits exceeded causing wood to fail.
willie:
--- Quote from: superdav95 on August 05, 2024, 11:08:39 am ---I’ve tried the Knox gelitan with mixed results. I found it works ok with my hog gut backings just fine but on some of my more extreme designs I’ve had failures of delaminating for reasons unknown. It seemed very similar consistency and working time to my glue or other stir bought hide glue but lost faith in it and decided I’d start making my own glue with exclusively sinew scraps and haven’t looked back. It may have been a bad batch too but now I’m hesitant to use it. I’m sure it’s just in my head........ A lot of guys use it so it must work.....
--- End quote ---
Knox has been reported to be made from bones. Other reports say it is a mix. Its manufactured as a food additive and I would suppose if a batch passes whaterever tests for food purposes, that tells us nothing about its qualities as a glue.
Dave you have tried both and see differences. I wonder how many that have had acceptable results have tried both and can offer an educated comparision as you have?
I looked in the box Bjorn sent me years ago I asked him what does he reccomend for sinew on bows. he sent me 251 (and a sample of 135 and 375 because I asked him to send me some of each because I wanted to see what the differences were)
the lighter weights are runnier consistency, and the heavier thicker,
I also recall instructions to mix with the reccomended amount of water which gave a given consistency. Thinning a heavier grade with water was not the way to go.
I used a double boiler as described above (a bowl floating in a small crok pot)
the glue would thicken as it spent too much time in the hot bowl and water evaporated and I did have to thin with water to maintain consistency occasionally.
I dont think that should be considered the same as over thining the thicker product to emulatte the thinner product
superdav95:
--- Quote from: willie on August 05, 2024, 06:05:42 pm ---
--- Quote from: superdav95 on August 05, 2024, 11:08:39 am ---I’ve tried the Knox gelitan with mixed results. I found it works ok with my hog gut backings just fine but on some of my more extreme designs I’ve had failures of delaminating for reasons unknown. It seemed very similar consistency and working time to my glue or other stir bought hide glue but lost faith in it and decided I’d start making my own glue with exclusively sinew scraps and haven’t looked back. It may have been a bad batch too but now I’m hesitant to use it. I’m sure it’s just in my head........ A lot of guys use it so it must work.....
--- End quote ---
Knox has been reported to be made from bones. Other reports say it is a mix. Its manufactured as a food additive and I would suppose if a batch passes whaterever tests for food purposes, that tells us nothing about its qualities as a glue.
Dave you have tried both and see differences. I wonder how many that have had acceptable results have tried both and can offer an educated comparision as you have?
I looked in the box Bjorn sent me years ago I asked him what does he reccomend for sinew on bows. he sent me 251 (and a sample of 135 and 375 because I asked him to send me some of each because I wanted to see what the differences were)
the lighter weights are runnier consistency, and the heavier thicker,
I also recall instructions to mix with the reccomended amount of water which gave a given consistency. Thinning a heavier grade with water was not the way to go.
I used a double boiler as described above (a bowl floating in a small crok pot)
the glue would thicken as it spent too much time in the hot bowl and water evaporated and I did have to thin with water to maintain consistency occasionally.
I dont think that should be considered the same as over thining the thicker product to emulatte the thinner product
--- End quote ---
yes Ive tried both hide glue purchased from 3 rivers, lee valley and some other place i cant remember right off at the moment. Ive tried the knox gel powder from the grocery store and of course my own glues. I did some crude testing with 16 inch long pieces of dried seasoned hickory all 2" wide/. the glued section was 2" for each of the sections i used for testing. from memory the the strongest holding glue was the homemade sinew glue that was by my estimation a close equivalant to the 251 strength glue from lee valley. The 192 glue from 3 rivers was great too and only slightly less strong. The sturgeon glue was pretty close to the 192 glue from 3 rivers. the weekest of them all was the knox but only by a little compared to the 192. all glues were mixed 50/50 granular by weight to water. each were soaked in cold water for about an hour or two before heating it up. Its hard to get the same glue consistency with the various grades. the runniest of the 4 glues was the sturgeon glue. the next was the knox. the next thicker glue was the 192 and then the last being the 251 grade. all heated to 60 degrees c. All the wood pieces were sanded and and wiped clean. In hindsight I should have sized with a number of coats each piece before applying the glues but i didnt do that. Each of the sections of the wood were heated over a radiant heat source fro about 30 secs prior to glue then clamped with and hand clamp. Each were let to dry for a week. I did not take pictures and i should have for reasons such as this right here. Im thinking a may redo the test and film it or at least take photos. I did this test a few years ago. It wasn't a very good test looking back now. I would do it a little different now. I had placed the test pieces in the bench vise and pulled with a scale attached with a section of leather. The only one that failed kinda was the knox. part of the glued portion pulled away with some wood attached on about half. possible wood failure or anomaly with that specific piece of test wood. All of the others broke at the vise on the wood and glue held. Tp redo this test again i would use a bendy section of mock limb that has simulated lamination with another piece of hickory. A true bending test is really the best way to test this imo. Like i said it was a crude test and not very scientific but gave me the info i needed at the time. I was initially concerned about the strength of my home made sinew glue and sturgeon glue in comparison to store bought hide glues. I was more then convinced of this and went ahead with confidence on my build at the time.
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