Knox Gelatin as Glue

Discussion in 'Setup & Repair [DB]' started by Martin Sheridan, Nov 10, 2003.

  1. Martin Sheridan

    Martin Sheridan

    Jan 4, 2001
    Fort Madison, Iowa
    Bass Maker
    A number of years ago I remember reading some things about the use of Knox Gelatin as a glue. They were published in a regional journal. My recollection is that it is a "cousin" to hide glue but not as strong. Does anyone have any information about this? I was fitting purfling into an instrument a couple of weeks ago when I realized I was out of hide glue, so I used the Knox Gelatin. I'm much more hesitant however to use it for the bass bar or neck joint.
  2. There was an article in the CAS journal a few years ago by someone who had used Knox gelatin to assemble a new violin. According to the author, the violin literally exploded when the weather turned damp. It's probably safe for purfling, but not for anything where an any holding strength is required.
  3. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
  4. That's interesting. I noticed that he says nothing about the relative moisture resistance of either hide or Knox. I'll try to find that old CAS article.
  5. Apparently there is a lot of disagreement about Knox gelatin as a glue. I have not been able to find the article I mentioned earlier, but I did perform a web search and found several instrument making/repairing sites with contradicting information about Knox gelatin. One violin making site recommended Knox as an excellent substitute for hide glue. Another site (a piano repair site) came up with the following quotes allegedly based on information from the Smithsonian Institution.

    "Knox Gelatin is food grade gelatin, but is not made from animal hides at all. It is made from rendering cattle bones. That means, it is comprized of a particular group of very light proteins which are edible, and which, in turn, were never incorporated in good adhesives. Granted, it has been rendered "pure" edible grade gelatin and as such retains very few fats (greases). It is these fats which go rancid and cause the glue to stink as mold spores from the air begin to multiply in it."
    "You see, hot hide glue contains many different kinds of protein. The strongest and best proteins are also the heaviest and most cohesive, as you might expect. So when you start using your glue the next day, stir the pot, because your best and heaviest glue has settled to the bottom. Definitely not the stuff that Knox Gelatin is made of."

    Who's right? I really don't have an opinion since I've never personally used Knox as a glue and probably never will since I buy my hide glue 10lbs at a time.

    Martin - why don't you try it on something else (other than purfling) and report back to us how it turns out.
  6. Martin Sheridan

    Martin Sheridan

    Jan 4, 2001
    Fort Madison, Iowa
    Bass Maker
    A luthier friend told me recently that some of the hide glue being sold to luthiers right now is actually bone glue from China and that it's no good.
    The Weishaar book has a section on hide glue and as I recall there are many different grades available according to strength.
    We're using a fish glue here at the shop made from Sturgeon bladders(?)which Anton says is much stronger than regular hide glue.
    I think I'll wait for more information before gluing my bass bar in or the neck in with the Knox.
    I know that with regular hide glude you can slosh some on a two pieces of wood, say 2"X 2" square, rub them together, and without clamping you can't get them apart ten minutes later. Maybe I'll try that with the Knox.
    After I used the Knox for the purfling I put the container in the fridge. Yesterday it took a lot of water and a long time in the glue pot before it would melt. It's susceptibility to moister weakening a joint could be a major problem?
  7. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    Is this the same "fish glue" that Kremer sells? If so, this stuff is fantastic. No heat required, very strong (it can be weakened w/more water), long working time, and dissolves w/hot water once it has dried. All the Robertsons guys use it; Dan Hachez turned me onto it.

    I haven't used knox gelatin for instrument repair, just the occassional potluck and Lion's club dinner.
  8. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
    Dick Tools (go ahead, type that one into your search engine) sells four kinds of animal collagen glue:

    * bone glue "for hard bonds"

    * hide glue "for more flexible bonds"

    * rabbit glue (powdered or sheets), "extremely strong slow-setting bonds, ideal for use in gesso"; and,

    * isinglass glue "obtained from the air bladders of Russian sturgeons. Low viscosity glue for the strongest bonds"
  9. Those looking for "G" rated entries try searching for Gunther Dick Tools ;)

    I'm really not interested in finding the strongest collagen glue. One of the most redeeming qualities of animal hide glue is that it is strong enough for to hold an instument together, but at the same time it will break/fail cleanly under stress. I look at it as a safety valve to preventing or limit damage from wood expansion stress.
  10. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
  11. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    Properly thinned, fish glue does "break" in the same manner as hide glue.
  12. How long have you been using fish glue Nick?
    Is it totally compatable with hide glue (i.e. will it stick to old hide glue)?

    I remember being in a shop that was using fish glue many years ago. It had a not too pleasant "fishy" smell to it. Is that not a characteristic of the better grades of fish glues?

    Where do you get it, and how does the cost compare to high grade hide glue?
  13. Martin Sheridan

    Martin Sheridan

    Jan 4, 2001
    Fort Madison, Iowa
    Bass Maker
    We get our fish glue directly from Russia.

    Perhaps we could try flavored Jello. It would be a lot more fun cleaning off the excess.
  14. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    I will spin my fish story later. I'm in Holland right now, and spending $$$ to access my email/Internet life. talkbass with you later...
  15. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    The only hide glue I trust comes from Eugene Bjorn Thordahl, perhaps THE world hide glue expert.

    Bjorn Industries, Inc.
    551 King Edward Rd.
    Charlotte, NC 28211
    704.364.1186 P
    704.364.1098 F

    I've been using the fish glue from Kremer, and agree with Nick that it's useful stuff. Smells bad, but not like fish...
  16. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    Okay kids. I've got some email time here...

    Kremer sells the stuff, as Arnold posted. It doesn't smell as bad as hot hide glue, by the way. (I wouldn't use it as perfume, lest I attract several pussycats.) Anyway, it does bond well with old, dry, hide glue (like when you are closing a seam?) It's very handy to have in the shop. Price wise, a kilo is $35. This should last you quite a while. It comes very thick, so thinning is neccessary.
  17. Jahm Mitt

    Jahm Mitt

    Jul 25, 2009
    I absolutely HATE people who sit around having opinions about what they once read about someone saying something about one matter or another, and then putting this out there to see what other people have to say about it...... "Ohhh is it true or is it not true etc., etc., etc."

    It reminds me of the never ending commentary - like I am not a huge fan of Micheal Jackson - never was... but I cranked on the TV and decided to watch his funeral - simply because it was on.

    And I would have been happy to have sat there and watched the whole thing - in reflective silence..... but could the TV networks do that? Nooooo way - they had an endless stream of chat show hosts and interviews...... and they just had to be yammering and yammering and yammering away, non stop with anyone and everyone and all the details and gossip and on and on and on and on they went...

    So I just turned the TV off.......

    Anyway - I am not much into "opinions and speculation" - because they **** me and so do the people holding them.

    I do stacks of wood work - and I got (back?) into using collagen based adhesives for binding up the thousands of pages of manuals I had to make in furthering my own interests - and these glues are composed of gelatin, glycerin and some water and some vinegar.

    It's like making a rubbery glue and it makes GREAT book binding adhesive - along the spines of books....

    And since I am an utter tight arse and I don't really want to cough up large amounts of cash for minimal results or quantaties - I decided to start using plain food grade gelatin in the construction of my instruments and cases (all sorts of instruments - not just musical).

    Now I prefer scientifically conducted tests over opinions anyday - but here is what I have done and found - vs what I know should be done.

    I tend to love using glue - and LOTS of it.... everywhere. I tend to buy it in bulk and I used to like using PVA - BUT:

    Because I live in the middle of nowhere and the local merchant either has none - or they charge heaps for it when they do get it in; I have kind of gotten a bit sick of the unreliability and or pricing of the agent.. so I am tending to prefer to steer around the supply problem - by using bulk quanties of granulated gelatin - shipped in 2.5Kg lots straight from the factory.

    I have found that ordinary Gelita Brand - food grade gelatin (in Australia), to be both very hard and a very very strong adhesive when bonding timber.

    In a few "special joints" I have applied a thick external bead of it (thick glue), around the outside of the joints, like welding reinforcement on pipe to plate welds....

    The glue has dried VERY VERY hard - sort of like the clear HARD epoxies that they use to encapsulate clear LED's with.

    On other lap joints etc., the bond has been so strong, there is NO way that joint is ever coming apart....

    I like heating my glue on my own glueheater and being a silly old man, talking to myself and making tut tut noises like an old motorbike and having everything just so.... and preheating the timber joint etc., and coming away - overall - being very pleased with myself and the assembly at hand.

    OK to get away from opinions and into proveable facts.

    There is NO doubt that when very high strength glue is needed, on very fine and highly stressed parts - that high strength glue MUST be used.

    BUT what I like to see happen, is that rather than people express opinons about other peoples opinions - I'd rather see YOU get off your arse and perform some tests - and then come back and tell us all about your results.

    What I'd like to see done, is for say 24 little blocks of timber to be cut from 3 or 4 "across the range" of timber types, from the same areas, with the same saws and surface preparation etc...

    And for each of the timbers to be glued with 4 types of collagen based glues, in a way that tests the bond strength of 1 or 2 cm2 of glued joint area; in tension and in shear, of both the end grain and in parallel to the grain joints;

    Using the same glue strengths of say 50:50 (dry glue weight and water); and all the joints be given the same clamping, drying and hardening time; and then to have the joints tested to failure on a calibrated tension machine - at say 12% relative humidity at 20*C...

    And then to run a series of identical tests in a heated and humidity controlled chamber - at say 40*C - in dry heat and then in slowly increasing levels of humidity of +10% relative humidity every 12 hours - up to saturation point... at a tension of say 50% and 75% of the dry cool specimens failure point - for each specific glue.

    The other issue that must be taken into consideration is the joint's surface area and the relative required strength of the bond - and is the bond strength primarily being made to resist tension, shear or peel?

    While I have NOT actually tested the bond strength of Australian Gelita Brand "food grade" gelatin; in a static rig with a tensionometer (?), I do know that in hammer and 2 bits of glued wood in a vice test; that this stuff is about 2 x as hard and as strong as PVA wood glue;

    I do know that collagen glues have fairly definite "pros and cons" about them - like every other adhesive has - but it being easy to dismantle, reglue and clean up - really appeals to me; there is NO nasty chemicals and fumes used in it's formulation; and I kind of like all the "pissing around" to make a really well crafted joint when I do use it.

    Setting aside the cost of the time to make it; I can make up 5 liters of this glue at 50:50 (weight for weight) proportions for about $60 - of the base material delivered to my door (huge advantage) fresh from the factory - where as quality PVA glue costs nearly double that.


    Rather than having opinions - I'd be prepared to perform the said tests on the basis of people supplying the materials to do so.

    What I want:

    I want 50 pieces of EACH of ones favourite woods, to be made to exactly 20mm x 20mm by 50mm long, and a 20 gram sample of each of the "hide glues" and any other glues that you prefer to use; to be sent to me and I'll construct a series of tests to determine and publish a table of the results of each glues failure points - in regards to tension, shear and peel, at relative humidity and at increasing humidity under fixed tension.

    So all you luthiers - send me your wares.

    Email me for my address.
  18. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    Mitt, there are a few of us around here who actually know a thing or two about luthiery and glues. You should take your superior attitude and shove it up your glue pot.
  19. JeffKissell

    JeffKissell Supporting Member

    Nov 21, 2004
    Soquel, CA
    Who are you and why are you insulting some of the best luthiers in North America?!?
  20. Marcus Johnson

    Marcus Johnson

    Nov 28, 2001

    "Jahm Mitt"? Give me a break.