Natural glue for finer woodworking & lutherie

A friend recently sent me home with some hide glue, and that was one of the best things that could have happened. I used it to finish gluing together my otherwise rickety gourd-based string instrument, and turn it into a polished, finished, pleasant-sounding instrument whose sound board doesn't slide off whenever I re-tune it!

Previously I'd tried with a resin/beeswax mixture to glue certain parts. In some places it worked, for a while. In one place it's still working quite well. But I think that the hide glue seemed a lot better at sticking where it mattered. Maybe the place where it's working well, got more resin as opposed to beeswax? I did hear about an instrument from ancient times that was caulked with resin and pegged together, so maybe that's an option too.

Do you have any natural and/or homemade glues that you use? Especially something that is very adhesive and would work when pegging or nailing might risk splitting such thin pieces of wood. I have a friend who is more strict of a vegetarian than I am, who I'm planning to make an instrument for, so alternatives to hide or animal based glues would also be very helpful. But this is a perennial thread so hopefully it gets to be useful for many people!

If dairy isn't beyond the pale then you could look into casein glue, which isn't hard to make. Other recipes for pitch glue that dont have wax but things like powdered charcoal to reduce brittleness might be worth playing with too. Latex sources that you could forage would be super interesting to play with. Wheat paste might do the trick too.

You might want to peruse the book Glue Gelatine Isinglass Cements and Pastes by Dawidowsky from 1884.

Thank you! I was thinking of something from dairy, but didn't quite know about casein glue yet. And thank you for the advice on adding powdered charcoal rather than beeswax. I had done that before but was trying the wax mixture for some reason--I think it was because it would show up less on the light colored wood.

Milkweed is always an excellent (and often unwanted) source of latex. Every time I go out to pick it my hands come back very sticky. It dries clear too, so that is sounding quite promising.

I think other powders work in pitch glues, I've seen various recipes (some shellac based) with brick dust or stone powder. Chalk powder or maybe even very fine sawdust might give a more neutral color.

I found a discussion elsewhere on the properties and preparation of casein glue and especially as it relates to lutherie: https://maestronet.com/forum/index.php?/topic/363085-casein-glue-help/

I made some basic glue with well drained yogurt and washing soda--we shall see how it works by tomorrow morning.

It looks like the yogurt glue is none too trustworthy. I could pull it apart quite easily. Perhaps it could be a paint binder, though. It definitely sticks when it dries, but I wouldn't trust it where there is much force being applied.

Here is another video on making something of better quality. Apparently some people have called what is essentially dried cheese, "casein plastic".  

This morning I am preparing purified casein...

Thats a pitty, I would have thought the milk glue would work.  Thanks for testing.

Do you have any left for a new test?  It probably won't work any better, so no point making a new batch.  I was wondering what it would be like if it has 2 or 3 days to cure before testing.

I was able to recover the rest of the glue and purified it--now I'm adding the alkali (this time a gentler baking soda). I added a lot of washing soda last time too, so maybe it was excessive. It is a good idea to wait a little longer.
My purification process was to add lots of water, mix until dissolved, precipitate out with vinegar, and then wash with rubbing alcohol. Hopefully this results in a better glue!

I might have been too harsh on the glue earlier. I found that the butter knife I mixed it with, even after washing, stuck and dried to the counter!

The new glue on some test wood seems to be holding up well, but again it's necessary to wait a while longer and see.

here's where it got on my radar, Steven Edholm of Skillcult making glue for a knife mod experiment

Cool to know about milkweed latex! Never heard that. I probably won't plant any, since it's apparently crazy invasive in some parts of Scandinavia, but if it finds its way to our area, it's good to know.

I've been toying with the idea of using some kind of protein-based adhesive (hide glue or possibly casein) and turning it water insoluble by treating it with tannin somehow. Haven't got around to trying yet, but it should work in theory, since the defining characteristic of a tannin is that it precipitates proteins out of solution... No telling what properties the glue will have afterwards, though. It would be nice if it remained strong and slightly flexible. I'll report back once I try.

Eino Kenttä wrote:Cool to know about milkweed latex! Never heard that. I probably won't plant any, since it's apparently crazy invasive in some parts of Scandinavia, but if it finds its way to our area, it's good to know.

There might be others--dandelion? I heard that russian dandelion is good for that. I wouldn't use anything other than milkweed here though, since they appear to be the best. Or perhaps sumac.

I've been toying with the idea of using some kind of protein-based adhesive (hide glue or possibly casein) and turning it water insoluble by treating it with tannin somehow. Haven't got around to trying yet, but it should work in theory, since the defining characteristic of a tannin is that it precipitates proteins out of solution... No telling what properties the glue will have afterwards, though. It would be nice if it remained strong and slightly flexible. I'll report back once I try.

That is interesting. If water is the solvent, wouldn't it precipitate out not as a glue? One would have to find a different solvent.

Update: Oh, wow! The casein glue is very strong!!!

M Ljin wrote:
There might be others--dandelion? I heard that russian dandelion is good for that. I wouldn't use anything other than milkweed here though, since they appear to be the best. Or perhaps sumac.

Yes, dandelion sap does contain latex, and it is somewhat sticky. It makes permanent stains on clothes. Don't know how good it'd be as an adhesive, though... I get the feeling that it wouldn't be very strong. It would be cool to try making rubber from it, though, just as an experiment. It would take a lot of dandelions...

That is interesting. If water is the solvent, wouldn't it precipitate out not as a glue? One would have to find a different solvent.

I'm thinking to use water as the solvent, make a very strong solution, and hope it has time to tan the (dried) hide glue before the glue dissolves. The glue I've made takes a little while to completely dissolve even in hot water, so with a very strong, cold solution, I figure there might be a chance. It's likely that only the surface of the glue will be treated, but combined with oiling, that might be enough. Well, there's only one way to find out. Yesterday I glued a few random objects (pebbles and small pieces of wood) together, using some hide glue I made years ago. Off to fetch some bark!

M Ljin wrote:Update: Oh, wow! The casein glue is very strong!!!

Yes it is! I made a guitar last year with commercial glue, but when my kids damaged it I've had great success repairing it with casein glue.

I am trying the tannin idea too!

I repaired a mug with my casein glue that had fallen from the counter. I had some astringent, tannic sumac bark decoction from far too long ago, when I boiled some sumac bark strips to make a pasta substitute, so I poured it into the mug and we will see. If it falls apart then it's no worse than where it started. If it holds, then all the better!

The tanning of glue is looking extremely promising so far! I made some strong willow bark decoction, and then dipped the dry test pieces briefly in it, set them to dry a little bit, dipped them a couple more times (with some drying time in between) and then put them in to soak a bit longer. The exposed hide glue did absorb water, but it didn't dissolve or turn sticky at all. It just turned sort of... gelatinous. More importantly, it's still functioning as glue! When I pry slightly at the glued pieces, they don't budge, though I suspect I could pull them apart while wet if I wanted to. We'll see how it seems once it dries completely, and if it tolerates being put in water. I suspect it'd be good to oil it after tannin treatment, to reduce the amount of water it absorbs. But yeah, promising.

Did you try how water resistant the casein glue is on its own, M? In the Skillcult video it sounds like it sets chemically to some extent at least, rather than just drying. Does yours soften much when wet?

Unfortunately it came apart after soaking, but I'll try again. Maybe it's for holding squash seeds...

I am not sure about setting chemically--I keep rehydrating mine as it gets a little jelly-like and it comes back. I'd compare it to hide glue.

Chris Clinton wrote:here's where it got on my radar, Steven Edholm of Skillcult making glue for a knife mod experiment

This is extremely helpful.

Working with hand tools in lutherie, there are always the little gaps in the wood where it's supposed to go together but doesn't quite. Where this happens I could glue-soak a few shavings to fill the gap, I'm sure! I will do this next time I have the chance.

This reminded me of this thread so popped it here just in case it's useful to anyone

Luthier talks about the advantage of hot hide glue for instrument making like guitars over modern alternatives, and how to use hide glue in guitar build and repair.  Looks like he is buying in granular form and making it as needed.

I'm lazy/cheap, and just use powdered grass-fed gelatin as glue. Granted, I've never tried gluing anything big like an instrument with it! I've just glued paper and cloth with it.

I found it worked great for bookbinding (there's picture of my bookbinding process here on permies). I usually just put a some gelatin in water in a little container. I either heat it up on my stove top burner on 2 or 3. Or, I put it on my woodstove. Here's the picture and description from my other post:

I made my own bookbinders glue by adding gelatin to water. It's a very thick mix, something like 2 tbsps of gelatin to 1/4 cup water. I added clove oil to help prevent the gelatin from spoiling

The picture above show the gelatin having "bloomed" in cold water. I haven't heated it up yet. It turns clear when it's fully warmed.

I apply it with a paintbrush. One downside to it is that it cools/sets very quickly, especially compared to store bought glue. There's not as much forgiveness with the gelatin glue. You really want to get your things lined up correctly when you adhere them to each other!

I made my first leather bound book over 5 years ago. The one made with PVA glue and the one made with gelatin glue have both held up equally well.

So, I tested the tanned glue by putting the test pieces in water over night. One of them held together just fine, still strong, the other broke apart completely. And here I thought I had treated them the same... Inconclusive result, more testing needed.

I like seeing the experimentation going on with the tannins and glue. If I wasn't so busy I'd enjoy playing around too. In the Skillcult video I posted above he brings up formaldehyde as making glues waterproof. That would lead me down the line of experimenting with seeing what effect wood vinegar/liquid smoke/pyroligneous acid would have on the glues. The aldehydes in smoke play the protein cross-linking (tanning) role in making buckskin, assuming that is still an up to date assessment. Just wanted to throw out that direction of inquiry. Didn't see anything in Dawidowsky  about it, but saw a reference in making elastic glue water resistant by the addition of even a small amount of caoutchouc (latex).

Chris Clinton wrote:I like seeing the experimentation going on with the tannins and glue. If I wasn't so busy I'd enjoy playing around too. In the Skillcult video I posted above he brings up formaldehyde as making glues waterproof. That would lead me down the line of experimenting with seeing what effect wood vinegar/liquid smoke/pyroligneous acid would have on the glues. The aldehydes in smoke play the protein cross-linking (tanning) role in making buckskin, assuming that is still an up to date assessment. Just wanted to throw out that direction of inquiry. Didn't see anything in Dawidowsky  about it, but saw a reference in making elastic glue water resistant by the addition of even a small amount of caoutchouc (latex).

Ooh, now that's a neat idea! As far as I know, the aldehyde theory for buckskin tanning still stands. Maybe smoking the glue while it's damp would work?

I have captured smoke in a bottle before--it is rather fun...

What if this smoke were to be "washed" to get a strong solution that would be used similarly to the tannin bath?