Making Liquid Hide Glue

[Dr.Al]

Introduction​

(jump straight to recipe)

I recently did some investigation into Old Glues and how well they stick. In that context, I mean old in the sense of "bought a long time ago and probably past its shelf life" rather than old-fashioned. For me, the ideal general-purpose glue:

1. Is strong enough (note the emphasis: I don't need super strong, I just want my dovetails to stay together).
2. Has a long working time to make glue-ups less stressful.
3. Is easy and pleasant to use (this is, of course, highly subjective).
4. Has a long (preferably infinite) shelf life as I hate the waste involved in throwing half-full bottles away.
5. Is easy to clean up.
6. Is reversible for if/when repairs are necessary.

Hot hide glue is nice in that it's reversible, it tends to lubricate rather than swell the joint (making it easy to get things together) and also it tends to pull joints closed and make invisible glue lines. Being a dry granule glue it has an effectively infinite shelf life. The biggest downside for me of hot hide glue is that you have to work quickly before it cools.

Liquid protein glues (e.g. Liquid Fish Glue or Liquid Hide Glue) have the advantages of hide glue but with longer working times (especially with liquid fish glue). The downside is that you're more likely to hit shelf life issues (although the experiments I carried out in the old glue test suggest that perhaps this isn't such a big deal). Richard Maguire has a nice post extolling the virtues of liquid hide glue.

Anyway, all of that got me wondering about making my own liquid hide glue. That would give the advantages of liquid hide glue but without the shelf life concerns as I could just make batches up from dry hide glue as and when required.

 

[Dr.Al]

Sources from the Web​

I did quite a bit of research to try to find out about liquid hide glues. The two readily available (in the UK at least) commercial options are Old Brown Glue and Titebond Liquid Hide Glue. Liquid Fish Glue is also available but as I understand it the method of making that is completely different.

Old Brown Glue is a traditional liquid hide glue made with glue, water and an anti-gelling agent (urea). Titebond Liquid Hide Glue is a more modern option that uses cyanoguanidine and ammonium thiocyanate as the anti-gelling agents. Titebond Liquid Hide glue is usable at low-ish ambient temperatures whereas Old Brown Glue apparently needs a little heating to around 25–30 °C for use (I've never used Old Brown Glue; my expectations of home-made liquid hide glue might have been tempered somewhat if I'd tried Old Brown Glue first!).

For home-made liquid hide glue (which will be more like the Old Brown Glue I think) I found several different recipes. They have some commonality, for example all involve glue, water and salt and all involve a period of heating at 60–65 °C. However, the ingredient ratios vary dramatically, as does the order in which things are done. Some specify the ratios as weights (which is better as it is more repeatable), some by volume (which will depend on the grain size of the glue so isn't ideal) and one doesn't bother to say whether they're weight or volume (which is entirely unhelpful). Two of the recipes are explicit in saying that the cooling following the heat cycle should be done as quickly as possible. The bloom strength of the hide glue seems to make a difference, with some recipes suggesting changing the ratio for different strengths.

I thought it would be useful to summarise the various recipes all in one place (in no particular order) so they can be more directly compared:

Looth Group Recipe:​

• Mix by Weight
• Uses 285 g Bloom Strength Glue
• 10:5:1 Cold Water:Glue:Salt

Add dry glue to water, leave until soft, heat at 63 °C for at least an hour.

Link to source.

Lost Art Press Recipe:​

• Mix by Weight
• Uses 250 g Bloom Strength Gelatine
• 4:4:1 Hot Tap Water:Gelatine:Salt

Add gelatine and salt to hot tap water. Stir, close the lid, shake vigorously, leave for 30 minutes. Heat for 2 hours at 60–65 °C. Shake a couple of times during the process. Leave in fridge overnight then heat again for 2 hours as before.

Link to source.

Hot Glue in the Modern Workshop​

• Mix by Weight (volume alternative offered)
• Uses 192 g Bloom Strength Glue
• 16:10:3 Cold Water:Glue:Salt (or 20:10:2 if using 285 g Bloom Strength)

Add glue to cold water and allow to swell and soften (1–2 hours), then heat to 63°. Add the salt and mix, then cool to room temperature.

Link to source.

Mortise & Tenon Magazine​

• Mix by Volume :-(
• Uses 192 g Bloom Strength Glue
• 12:12:1 Water:Glue:Salt (I think - they use silly units so I might have got the ratio wrong).

Mix and soak overnight, then heat to 60 °C for 2 hours.

Volume mixes are inherently less accurate than weight mixes so I've tended to avoid them (the volume for a given weight will depend on the granule size).

Link to source.

Popular Woodworking​

• Doesn't specify whether the ratios are by weight or by volume :-(
• Bloom Strength not specified
• 3:2:1 Water:Glue:Salt

Mix water and glue and soak overnight. Heat to 60 °C then add salt. Cook for 2 hours. Cool quickly in the fridge and leave overnight. Cook for another 2 hours.

Link to source.

My Peculiar Nature​

• Mix by Volume :-(
• Uses 260 g Bloom Strength Glue
• 3:2:1 Water:Glue:Salt

Mix water and glue and soak overnight. Add salt and heat at 60–65 °C for 2 hours. Cool quickly in the fridge and leave overnight. Cook for another 2 hours.

Volume mixes are inherently less accurate than weight mixes so I've tended to avoid them (the volume for a given weight will depend on the granule size).

Link to source.

 

[Dr.Al]

My Recipe​

Summary​

• Mix by Weight (as it's much more repeatable than mixing by volume)
• Using 280 g Bloom Strength (Hosco brand) Hide Glue Granules
• 3:2:1 Cold Water:Glue:Salt
• Soak water & glue for two hours, add salt and heat for two hours, cool quickly, heat for two hours, cool quickly.

Detailed Process​

• Put three parts (by weight) water into a glass jar or HDPE squeezy bottle. HDPE bottles are more temperature resilient than the more common PET ones.
• Add two parts (by weight) Hosco hide glue granules to the water.
• Stir and leave to soak for two hours (I suspect a shorter time would be fine).
• Heat in a water bath to between 60–65 °C glue temperature (I'm using a baby bottle warmer set to 55 °C).
• After half an hour it should be up to temperature, so add one part (by weight) salt, stir it in and then shake vigorously.
• Continue heating at 60–65 °C glue temperature for 2 hours, shaking vigorously every 40 minutes.
• Place the hot bottle directly into the fridge to cool it quickly and then leave it overnight.
• The following day, heat to 60–65 °C glue temperature for another 2 hours (shaking every 40 minutes again).
• Again cool quickly in the fridge.

 

[Dr.Al]

Results​

That recipe was the one that I did on something like my tenth attempt (having followed all of the recipes I listed in the "Sources from the Web" section with little success. Cooling down quickly definitely seems to make a difference: one of my earlier attempts was exactly the same as the one listed in the recipe but without the fast cooling and the glue ended up solid at about 23°C. When I repeated the recipe but cooled it in the fridge after each heating stage, it was pourable (if rather gloopy). Once I'd realised that the cooling stage was essential I went back and tried a couple of the other recipes (the Lost Arts Press one and another one I can't remember at the moment) but they didn't work even with the cooling stage - I don't think there was enough water for it to remain fluid.

I've found that the glue lasts for a few weeks in the pourable state at room temperature but gradually gets to the point of needing to be warmed a bit to get it flowing nicely. Even when freshly made, a bit of warmth aids in reducing the viscosity and making it easier to use. Contrast that with the liquid fish glue that can be used at 15°C without any issues. Titebond Liquid Hide Glue is similarly gloopy to the fresh liquid hide glue but that viscosity is fairly consistent with age.

The lollipop stick tests I did on the successful batch of hide glue show that it works well as glue so that's definitely a good thing!

The obvious question is: was it was all worth the effort? Perhaps not, but it was an interesting exercise nonetheless. The home-made glue works well and has all the nice properties of the other liquid protein glues (as described by Richard Maguire). The home-made glue is easier to use than hot hide glue: bung the bottle in a mug of hot kettle water for a few minutes, then pour and apply. Titebond Liquid Hide glue is easiest to use if you follow the same process. Liquid fish glue is, however, easier and at reasonably comfortable ambient temperatures it doesn't need the mug of hot water (although it certainly does need it when the weather gets cold).

Liquid fish glue remains my favourite glue (it has a much longer open time than TB liquid hide glue or the home-made stuff), but it's been fun to play with alternatives and all the experimentation has made me more confident in using both the liquid protein glues and the more traditional hot stuff.

 

[AJB Temple]

Very good. I went down a similar rabbit hole when dabbling with making violins. In Cremona many workshops use fish glue, partly because of cold set properties.

 

[Mike G]

Great stuff Al. This was an experiment I had wanted to do one day, but you've saved me an awful lot of work, a lot of cleaning up, and a lot of wasted material. I have long wanted to swap to a more traditional glue than the PVA I use habitually, particularly for the long open time, but also just for the bragging rights .

 

[AndyT]

These posts need to be a "sticky"!

 

[AJB Temple]

My (rather limited to be frank) experience over the years with hide glue and fish glue, is that fish glue is easier to take apart if / when an issue arises. It is more hygroscopic (so not great in high humidity environments) and that helps separation when needed, and it is a bit easier to clean up from disassembled parts .

 

[Dr.Al]

My (rather limited to be frank) experience over the years with hide glue and fish glue, is that fish glue is easier to take apart if / when an issue arises. It is more hygroscopic (so not great in high humidity environments) and that helps separation when needed, and it is a bit easier to clean up from disassembled parts .

That's interesting to know. I've yet to have to take apart a joint made with either of the protein glue types but it's nice to know that fish glue works. I'll probably stick with something like Titebond 3 for outdoor stuff so hopefully won't have to worry about humidity in fish glue applications.

 

[PAC1]

I have been using hide glue for two years now. I do not regard making it as a precise science. I tend to put more 50% more water than the hide glue as a starting point and then adjust it after the second cook. Which usually means more water. A good glue pot is essential.

 

[Dr.Al]

I have been using hide glue for two years now. I do not regard making it as a precise science. I tend to put more 50% more water than the hide glue as a starting point and then adjust it after the second cook. Which usually means more water. A good glue pot is essential.

I've found similar to be true with hot hide glue. From my point of view the downside of the hot stuff is that you have to work quite quickly.

Making (room-temperature) liquid hide glue seems to be much more fussy - hence all my experimentation.

 

[thetyreman]

I've used urea capsules instead of salt, worked perfectly, and once set seems just as strong as pure hot hide glue, I found between 5-10% of the glue weight was just right, didn't really experiment further but probably will when I get the time, it has the bonus of staying useable for much longer in the fridge as well, I think it's a good compromise when I need more open time, it just doesn't have the same 'grab' as hot hide glue which is sometimes very handy. I always heat it up at 60 degrees in a cast iron double pot, bought mine from jacob for a bargain a while back.

 

[SteveMP]

Very cool. I'm kind of lazy and just buy the premade stuff either OBG or Titebond, but I like the "science" of it.

 

[Cabinetman]

Very interesting Al, can’t add much but to say the only memory of it from probably the 60’s was the appalling farmyard smell, back when every workshop had a cast iron glue pot they wouldn’t have been able to reproduce the refrigeration stage so maybe they had a different recipe?

 

[PAC1]

I've used urea capsules instead of salt, worked perfectly, and once set seems just as strong as pure hot hide glue, I found between 5-10% of the glue weight was just right, didn't really experiment further but probably will when I get the time, it has the bonus of staying useable for much longer in the fridge as well, I think it's a good compromise when I need more open time, it just doesn't have the same 'grab' as hot hide glue which is sometimes very handy. I always heat it up at 60 degrees in a cast iron double pot, bought mine from jacob for a bargain a while back.

For me it is not just the grab of hot glue but I have not been able to get an “invisible” glue line with OBG. You need to plan your glue ups with hot glue. So far I have only had one problem which was quickly rectified.