hide glue versus grocery store gelatine?

[Julian Macdonald]

Hi all.

Would anyone like to comment on the idea of using ordinary grocery store powdered gelatine in place of hide glue? Correct me if I'm wrong, but I understand they're basically similar stuff.

With the gelatine I've glued test pieces in every combination of leather nap, leather grain, card, fake leather cloth side, fake leather plastic side, and tyvek (the last three with the idea that they might be useful for bellows, but that's another story).

Results are mostly promising (see below).

But of course that doesn't tell me how durable it would be or how it would stand up to fatigue from flexing. I'd welcome any comments.

 

Test strips 25mm wide with overlap of 25mm, so glued surface of 25x25. Approximate breaking stress in shear in kilos to nearest half kilo estimated by hanging weights off them.

 

Leather nap to: nap more than 6 (leather broke first). grain 4.5. card at least 8.5 (stopped measuring). tyvek 5.5. fake leather cloth side 1.5

Leather grain to: card 7.0. fake leather cloth side 2.5.

Card to:  card at least 9.5.  fake leather cloth side at least 8.5.  fake leather plastic side 2.5.

Fake leather cloth side to: cloth side at least 8.5.  plastic side: 0.5.  tyvek: 3.0

Fake leather plastic side to:  plastic side 0.5.  tyvek 0.5

 Tyvek to:  tyvek 6.0

The results for fake leather seem oddly variable. I may have been treating the samples differently in some way that was more important than I realised.

Fake leather plastic side was hard to glue because surface tension made the glue bead very quickly so it was hard to wet the whole surface.

Fake leather cloth side absorbed the glue very quickly. I put on three prep coats at intervals of 30 to 60 seconds allowing them to soak in before the fourth coat wetted the surface long enough to join the pieces.

Cheers

 

 

[Steve Schulteis]

I've heard of grocery store gelatin being used to fix a violin when the owner couldn't get to a repair shop in time for a performance. The results were reportedly good, but I don't know how long that repair was left in place.

[Alex West]

I've also heard of woodworkers trying to use gummy sweets (suitably melted/dissolved) as an alternative to old-fashioned joiners glues.

 

Tried and trusted rabbit skin and fish glues I would suspect have greater consistency and more reliable initial tack and final strength/flexibility than a food store gelatin of uncertain composition from a variety of animals.

 

What's the motivation - cost?

 

Alex West

[wschruba]

If it's cost, Schaff piano supply sells hide glue crystals.  Not super fancy, but they should be available anywhere there are pianos (but you might need to go through a technician to get them).

 

If it's the process (specifically the heating/maintaining temperature), that's a bit more understandable.  Automatic glue pots are...uncommon now.  I bought my Hold Heet [mostly unused] at a surplus auction.

 

Lots o' people are concerned about having to mix a new pot EVERY TIME you glue, but the reality is you only need fresh glue for high-stress (ie, instrument case) joints.  I rotate my glues in little 3-oz bottles, relegating the fresh glue to structural joints, and the day-to-week old stuff to everything else.  It'll keep in the fridge for 2-3 weeks...

 

John Tuttle, a local player-piano restoration specialist, has an exceedingly thorough explanation of how to use hide glue crystals...https://www.player-care.com/preparing-using-glue.html#method

[Julian Macdonald]

Thanks for those comments.

Alex: motivation: mainly curiosity. Plus  convenience: I live in provincial Australia** and I haven't found a retailer with hide glue nearby.

wsschruba: thanks for the great John Tuttle link. I note the references to strength, and creep of PVA glue. I assume the main issues for a bellows would be shear load between the card and the hinge material when the bellows is fully extended, and maybe fatigue at the point where the gusset crosses the bottom of the valley hinge.

My tests used glue that had been in the fridge for a week after first less orderly experiments.

 

**"Provincial" is a bit of a self-deprecating joke. As I say to foreign friends: "Come and visit us in Canberra! We can see the sights and then go out for lunch!"

[Alex West]

Julian

I get my rabbit skin glue pellets online and having just done a quick check, there are plenty of bookbinding and fine art suppliers in Australia who should be able to supply you albeit from Sydney, Melbourne or NSW.  If it's bellows you're thinking of, then Crabb's used to use a wheat or starch paste glue (or so I'm told) which you can also get in Aus. 

 

The concern with PVA for bellows is not so much creep, but that it remains somewhat flexible when set and the flexiblilty changes with temperature.  It might not be a huge problem in Australia, but in the cold, the bellows joints will become less flexible and the whole thing sluggish and hard to operate.  Rabbit skin glue (and also Titebond, I'm told) dry "brittle" so without losing airtightness, the joints form micro-cracks as they are flexed and are consistent over a wide temperature range.  (I've not tested this, just relied on teh wisdom of other makers and repairers)>

 

Alex West 

[Julian Macdonald]

Alex: "and also Titebond, I'm told...."

I guess you mean Titebond liquid hide glue here, since they also do PVA? Cheers 

[Alex West]

6 hours ago, Julian Macdonald said:

Alex: "and also Titebond, I'm told...."

I guess you mean Titebond liquid hide glue here, since they also do PVA?

Julian

 

No, I meant Titebond Original - it's an aliphatic resin.  I don't find Titebond liquid hide glue easy to work with

 

Alex West

[RogerT]

A vote for Titebond liquid hide glue from me too. If it's cold put the bottle in a bowl of warm water to make a flow a bit. 

[Chris Ghent]

Geoff Crabb told me when they were having trouble getting glue sometime after the war he was sent out on his bike to buy wine gums which they rendered down to extract the gum arabic for use on bellows.