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I'm within a day or so of being ready to glue a front back on a guitar. I want to use hot hide glue and I'm wondering if anyone has any advice on how to proceed. My main worry is how do I keep the temperature high enough throughout the operation. Somewhere, I think on frets.com, I read about a front being glued on a bit at a time but no details of exactly how this was done this were given. How much is done in one go? and how does one ensure there ane no missed bits? Any help will be appreciated.

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Whilst I was doing this glue job I remembered something I read years ago in a book about violin making. The procedure was;

1 put glue on both surfaces.

2 Put paper on the glue and glue on the paper. remove excess paper.

3 clamp together.

The idea of the layer of paper between the glue layers suggested easier dismantling in the future. Does this ring any bells here?

Seems to me that I've heard of using paper in the glue joint on violin tops before too but I believe it was Frank. on the other site that explained that violins are made to be taken apart periodically while guitars are not. I don't think I would want to leave a weak layer in my glue joints on a guitar.
Ron... I'd hate to have to rely on the bond strength of paper to keep a violin top on. When I was building , the recommended method was full strength HHG for the back, then reduce strength by adding an equal amount of water for gluing the top. Not something I would recommend for a guitar top however!
I wondered if you used an open pore paper like newsprint, would the glue penetrate the paper like resin penetrates fiberglass? I might try some experiments to compare a wood to wood joint with a wood, paper, wood joint.

Worth a try! Where would we be without experimentation? My thought is that although the fibre strength of newsprint would  be fairly low, it's porosity might add considerably to strength in the same way as papier mache.

With a heavier grade or a paper with clay added the glue should only bond externally and the fibres in the middle could separate. That's why wood turners sometimes mount small articles to be turned with a paper joint to make them  relatively easy to remove and to avoid drive spindle marks.

 If ease of separation is what you are after as in violin building it might be that newsprint might be just as difficult to separate as a glue-only join. On the other hand it might be a bit more absorbent and loosen up with  a little steam or warm water. Who knows? Only one way to find out!

 

Hide glue is wonderful stuff and when used correctly it's pretty clear why it has been the standard of the Guitar industry for all of time.  

 

One has to ask themselves though if hot Hide glue (HHG) is all that for any and all applications and of course the answer is no.  Where HHG shines IMHO is it's ability to be "serviceable" in so much as we are permitted the luxury of taking apart HHG joints at any point even 100 years after the joint was initially cured.  Another area where I remain a HHG evangelist is HHG's crystalline and very hard nature after a proper cure.  Have you ever tried to chisel off a brace glued with HHG?  The dried glue is hard, very hard and glass like with a very, very thin glue layer.  As such some of us, even though we can't prove it..., believe that HHG transmits/transfers vibrational energy better than say softer glues that are common place in woodworking today.  But I digressed... again...

 

Here are some possibilities for the OP, Ron Ellison:

 

The major consideration as you noted was being able to be super human and assemble and fully clamp the entire joint in say 15 - 30 seconds before the HHG gels.  Once it jells, and we may not know..., the joint is forever weaker if the joint was not fully assembled and clamped when the glue gelled. 

 

1)  Some makers such as George Lowden have a press that utilizes a single, large wheel that is attached to a caul that matches the perimeter of the specific guitar size, shape being glued-up.  The rim is placed in the press and a bead of HHG is applied around the rim, the top or back is placed in place (some form of registration would be advisable) and the operator spins the wheel and lowers the clamping caul.  Obviously this can be accomplished in far less time that using a go-bar deck with say 30ish individual go-bars.

 

2)  Some makers play with the viscosity of the HHG making it thicker and then they apply a bead with a squeeze bottle around the rim - this is done working very quickly.  The bead initially cools on the outer layer (picture a gel cap in your mind) but the inside glue remains hot enough to not gel.  Clamps are quickly put in place and Bob's your uncle...  This method probably buys you a bit more time before the glue gels.

 

3)  Violin makers have been using hot rooms for centuries.  A hot room is a small space that is heated to say 120F and in that room in our boxer shorts... we have all the time that we wish to have to assemble our instruments without fearing the dreaded gelling of the HHG.

 

Lastly though I have to ask why one would wish to glue on a top or back on say a guitar with HHG if you have other choices?  Unlike top or back bracing, the bridge, etc. gluing the plates on a rim is not an application that I believe would sonically benefit in a noticeable way for the use of HHG.  Unlike Luthiers in days past we have other choices AND we also have big box stores too...;)  I'm also aware that some folks believe that HHG for every joint in say a guitar produces a superior guitar.

 

FIsh glue IMHO dries just as hard as HHG, is similar in the sort of glue that it is, has an open time longer than Titebond and unless the instrument will be kept in an aquarium or some place with 100% RH fish glue is a great choice.  It is also serviceable and will come apart when we wish it to with heat and some moisture.

 

And lastly many great guitars have been built with Titebond, Elmer's Wood Glue, LMI White, etc.  I know that we all need to refine our chops as we wish but personally I think it's just as important to avoid using something in an application that it is not all that great for for one reason or another i.e. we may not get the joint clamped in time... and risk a joint failure later in life as a result.

 

Hope something here helps.

I heard that Sam Hutton used HHG to put Tolex on Fender amplifiers "back in the day".  I met Sam Hutton a few times many years ago, and now I regret that I never asked him to share his cabinetry techniques with me.

 

Using HHG for Tolex actually makes perfect sense.  Unlike contact cement, HHG doesn't "outgas" organic vapors as it cures, so isn't likely to distort the vinyl covering.

 

I'm overhauling five Ampeg SVT's right now, and a few of them need to be recovered.  I'll be finding out soon if HHG is a good choice.

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