Fish glue alternatives?

[bruce d]

Seeking some sage advice.

I am looking for a glue with one specific characteristic: I need to glue a bunch of pieces of wood together and then later separate them without harm. Seccotine was good for this in the old days but it is no longer available as far as I can tell. Using Titebond or similar and then applying IPA is not an option, the pieces are a bit too thin and spindly to survive the process.  I have tried a cheap PVA in the hopes of getting a poor bond but it actually gave a very strong, nearly bulletproof join. 

So, I suppose, a temporary glue. There has to be some clever product out there or a hack.

Any ideas?

Thanks in advance.

[Charter33]

Hi Bruce,

Not to sure if this technique would be appropriate as I don't know if it would work for your particular application, but one trick I use when wood turning is to glue wood together with standard PVA, but with a piece of paper in the joint. It holds things together well enough for quite aggressive shaping but can be split apart once the job is done. A sharp chisel usually does the trick. The paper/glue left on the joint surface can then be sanded or scraped off.....

Another possibility might be to use a hot melt glue and then heat the wood after shaping. Seen this done but to be honest I haven't tried it myself.

Good luck!

Cheers,

Graham.

[bruce d]

Thanks Graham, I hadn't thought of paper between the pieces ... even though I have done that in bigger woodworking jobs!

I will play around with paper, who knows?

Still hoping for a clever sticky-stuff of some kind. 

[Jaager]

This is an unsolved problem for me, too.

 

I need a bonding agent that will survive significant shear force and will readily release without affecting the PVA bonds next to it.

 

Duco is a cellulose nitrate adhesive that releases with acetone.  PVA is unaffected by acetone.  But Duco as poor shear strength in my experience.

 

Fish glue is a hide glue -  they are protein based adhesives.  The protein is totally denatured in the presence of ethanol and heat.   It is a strong adhesive that has a long history of competence. 

The traditional form of hide glue is from a hot pot.  This avoids needing a solvent, but is complex and time consuming.  More work is needed than squeezing out a blob.

I assume that the solvent in Seccotine is water.   Franklin makes a liquid hide glue, but the water content is significant.  Old Brown glue is supposed to be better quality, but still water.

I use it for temporary timbers filling the spaces between or within frames.  It is better to have a solid hull when shaping, faring, and sanding.  No movement of timbers and the edges are crisp after it is done.

I could not avoid using too much hide glue, so even the timbers of a pilot schooner were too thick to get a bond release without the heat gun cooking the Maple frame timbers.

I suppose I should have used dots of glue.  Also, if a layer of newspaper or similar loose fiber paper was a part of each layer, the ethanol would wick in more readily, but glue would be needed on each side of the paper and I want quick and dirty.

 

I next tried Scotch perm double sided tape.  Ethanol affects it.  It has good enough shear strength most of the time.  But to increase the strength, I burnished the first side.  It increases the hold.  Too much.  It releases well enough, but the burnished side lease the adhesive behind.  I can find no solvent for it, so it is a mechanical removal process, between frames.  It is maybe 200 or more gaps.  HMS Centurion is still waiting for me to recharge my initiative to tackle that tedium.

 

My current thought is to use rubber cement.   Apply a layer on each surface.  Left it dry.  Stick the two together.

The solvent is N-heptane.   It does not affect PVA bonds.  I suppose that using it as a solvent instead the a rubber cement thinner wants it being done where there is excellent ventilation and no chance of ignition.

[bruce d]

43 minutes ago, Jaager said:

My current thought is to use rubber cement.   Apply a layer on each surface.  Left it dry.  Stick the two together.

 

My limited experience with rubber cement on wood is not encouraging. I got a few 'hard spots' with a solid grip on the wood for no known reason.

The paper suggested above got me thinking. Have you tried mucilage? 

[mtaylor]

Can you immerse the glued parts in alcohol?   If so, I've used PVA (Elmer's School Glue is my usual first choice) and when time to separate and just dropped them into alcohol.  I don't force them apart but let the alcohol soak and dissolve the glue.  Sometimes it a matter of maybe an hour and other times it's a lot longer.

[Jaager]

25 minutes ago, bruce d said:

Have you tried mucilage?

No.   It may not be available.  My search points to it being another protein based adhesive.

 

I suggest that you give Old Brown glue a test, but use dots.   Try a layer of wedding gift tissue paper along with it.

It should mechanically separate.  Hot ethanol will have it roll up into little balls.

 

StewMac has this really neato seam separator knife:

 

[bruce d]

19 minutes ago, Jaager said:

No.   It may not be available.  My search points to it being another protein based adhesive.

 

This is on my 'to-do' list (minus the flavouring)...

 

[eyfeinsod]

Hi,

I have experience as a luthier, We use hide glue(available from Woodcraft supply). it comes in flake form dissolve in water @ 104 * F or find an new or old glue pot . all Violins etc. are glued together with hide glue very very strong but can come apart  for maintenance and or repair.   Many other trades used hide glue furnaturemakers etc.  

[mgdawson]

Hi Bruce

 

The Titebond liquid hide glue rather than needing heat is actually water soluble hence can be taken apart using water which I've needed to do on one occasion, I've also thinned it with water before application, I've not tested its strength when thinned however.

 

Perhaps try the paper trick with some titebond hide glue thinned to give 'just enough' grab.

 

Also has a long open time which can be an advantage or disadvantage depending on the job.

 

Mark

[Dr PR]

This is just a guess since I don't know what you are trying to glue together and what you want to do after that.

 

How about shellac? You can glue everything together with shellac, work it as a single piece and later separate everything with denatured alcohol (95% ethanol). An added bonus is that the shellac will leave a good finish on the wood that can be left "natural" or painted.