Top Removal, but where the hide glue was full strength?

[PhilipG]

I have read the past posts about removing a top and have removed

tops from violins with the advice I've received.  But none of

the tops have been affixed with full strength hide glue.

Like the one I have now.  

I have heard from one repair shop about a technique called a

"bath". I had never heard of this before and I can only

presume that this does NOT mean that they soak the violin in a tub

of some liquid.  Rather, more than likely, it is to use some

chemical to soak into the seams between the top and the

sides whereby the glue eventually weakens to the point where

the top will come off very easily.  

I had also heard that this "bath" method takes literally a few

weeks to work.

Has anyone heard of this?  

I may have to take the top off this violin and I would love to be

able to do it without using a heated spatula or by any

forceful means at all.

What is good about this particular situation is, I can literally

take my time with it. Weeks, even months if necessary.

 I don't want to rush things.

[Jeffrey Holmes]

Using small amounts of alcohol (from a hypo), wicked into the seam on the opening knife, will usually help dehydrate the glue and aid in opening the fiddle. I also use a block and small sand-filled hammer at times, but only in certain areas of the top (not on the outer bout edges)... but frankly, this takes a bit of a "touch", so I'm a little uncomfortable recommending the method without being able to look over your shoulder while you try it....

[Brad Dorsey]

Are you sure its hide glue you're dealing with? To test it, see if you can find a bit to scrape off and put it in water. Does it soften and swell up like hide glue does? Elmers glue softens and turns white upon immersion.

If it's not hide glue, it could any number of things, some of which are not water-soluble. Some people report success using vinegar to release Titebond, but I've never tried it.

[Jeffrey Holmes]

Good point, Brad...

[PhilipG]

Hello Brad and Jeff and thanks for your replies. Yes, it is

definitely hide glue and I should have initially admitted that I am

the full strength hide glue culprit. I came to realize after the

fact that it was stronger than it should have been.Interestingly, I

found a test piece of wood – actually two pieces that I had

joined together with the same strength glue. Before I went to work

yesterday, I decided to soak a piece of paper towel with white

vinegar and then placed it on the seam, where the two pieces were

actually joined together. When I got home later in the day, I was

able to pry the two pieces apart with very little effort.On this

violin, obviously, the seams are much tighter but I believe, if

necessary, I can use a very thin razor to open the seam just

slightly, and then simply allow the same type of vinegar soaked rag

to work its magic, in however much time it takes. Even weeks, if

necessary.  In this, I believe that any impatience

at all would do nothing but cause even the slightest bit of damage.

[Dan Keller]

How do you make the glue weaker for the use of gluing the plates on?

Do you increase the % of water?

If so what is the ratio?

- Dan

[mamawelder]

I've had luck just using warm water and feeding it in on the thin blade after which I use a hair dryer to warm the wood. This works especially well when getting the top to separate from the top and bottom blocks. Then I use a combination of parting knives and the tap technique mentioned. It's that first point of entry that can get dicey. I try to start the release from the lower bout underside on cellos. I don't mess with dismantling violins so I don't have suggestions on where the best starting point is on them.

~Linda

[M_A_T_T]

quote:

---

Originally posted by:

Dan Keller

How do you make the glue weaker for the use of gluing the plates on?

Do you increase the % of water?

If so what is the ratio?

- Dan

---

Yes, more water. How much, I don't know for sure, as I am still experimenting. I've heard you want the glue for the top (the back is glued on with stronger glue because most of the time it is the top that you remove) to be like water almost, but don't take that as fact yet.

[Janito]

An obvious point: the blocks should be 'sized' with glue and planed again before attaching the top.

It is amazing how strong protein glues are: witness the tenacious bit of snot that will not come off the library book page or the clumped hair of the brush that was washed 'well'.

[Magnus Nedregard]

You might also add a small amount of glycerine to the glue. Just a drop or two.

[Janito]

How do you make the glue weaker for the use of gluing the plates on?

Do you increase the % of water?

If so what is the ratio?

----------------------------------------------

Here is a starting formula for the top plate:

1 part hide glue to 2 parts cold water. This can be achieved by weighing or by eye.

Can be diluted further by dipping brush lightly in glue and then in the hot water of the bath before application to ribs etc.

[josborne]

Would the top be a place where liquid hide glue would be

acceptable? I would think that the increased working time would be

an advantage and it would probably not be as strong.

[Jeffrey Holmes]

Just a quick comment...

Although warm water, vinegar and other water based "solvents" will soften hide glue, I rarely use them in removal of a top or back. The problem is that they also soften the wood (especially spruce) and can distort things a bit (a real drag around the button). Using a solvent that dehydrates the glue (low moisure content "anhydrous" alcohol), sparingly, usually yields much better results for me.

Now please notice, I say "rarely", not "never". In the end, one has to determine what will work best for each individual situation... helps if you've encountered similar situations in the past, however.

Josborn; While one of the participants on this board has suggested a good use for it (fixing temporary aligning cleats) and some use it for labels, I don't keep liquid hide glue in the shop and personally wouldn't use it for attaching the top (or any other structural part). Learning how to prepare glue for various uses (strength additives) is as important to making & repair as sharpening your tools... and once you have the hang of it, it's not all that difficult.

[Mat Roop]

Regarding vinegar... it is an acid and as such will rot the wood (or any natural fiber) that it comes in contact with. The more you use, the longer you let it sit on the wood and the higher the concentration... the more the wood will deteriorate and lose strength. I like the verrrrry careful application of alcohol to open seams.

Cheers, Mat

[Lyndon Taylor]

I would rely on my trusty knife, alcohol scares me seems like an

accident waiting to happen, as to what thickness hide glue; to glue

a top on about twice as much water so that the glue is clearly

dripping off the brush, not flowing smoothly like it should be for

full strength, and no definetly not the place to use liquid hide

glue if there is any place, I don't own any, sincerely Lyndon J

Taylor

[Magnus Nedregard]

As far as my limited experience goes, adding water doesn't really make the glue really weak. I use really liquid and runny glue for crack repair and it is still strong glue! Adding glycerine (I've heard some people use some sort of starch too) really has an influence on the bond strength.

Some people treat the table edges (esp. if new) with gum arabic too, before they glue it to the ribs. This way they will come off intact, great idea for new instruments!

[Joe Christian]

I agree with Jeffrey, alcohol is your best bet. As for the vinegar,

it is probably not much faster than water on hide glue and

will leave a residue on/in the wood. I would also avoid the razor -

a thin, dull and smooth butter knife or thickish spatula works

well. There are some nice antique butter knives that are made from

one piece of metal and that have thin uniform blades. Whatever

opening knife you choose, make sure that it has a very secure

handle.

 What you are aiming for is to crack the glue just ahead of

the opening knife with a gentle wedge action. A razor is prone

to cutting into the wood around the glue. That's not to say

that a razor or thin sharp knife isn't helpful. I use one to

cut the rogue wood fibers that start to separate from the plate

instead of the glue. Another advantage to the butter knife is it's

length. You can come at the block areas from behind if the split of

the wood dictates it. You want the opening knife to be a

perpendicular to the grain of the plate as is reasonably possible

to avoid cracking the plate.

Academic BS follows:

On the alcohol, it works, but I'm not convinced that it does so

through dehydrating the joint. This is something that I brought up

years ago on TOBI. when people used any pure alcohol for the job

(with good results). If it does open the joint by dehydrating

it, anhydrous should work and non-anhydrous shouldn't work very

well and in the dry winter months, neither should work well. Since

there isn't any liquid water in the glue joint, we are talking

about removing water vapor. Also, anhydrous doesn't stay that way

for long. It readily absorbs atmospheric moisture and loses it's

hygroscopic nature. At the lab, when we needed anhydrous to form

crystals from proteins, we opened a new bottle. 

I asked Art to get some anhydrous and we used it with good result.

So, I think it works better, but I'm just not sure it's because it

removes moisture. I suspect that it causes something (glue or wood)

to swell/shrink just a tiny bit. It could be that it is able

penetrate and foul up the adhesion just enough to let the wedge

action work better. It could even be that by evaporating, it

cools the joint and sets up a stress. This is academic and I may

very well be wrong. It's just booze for thought.

--Joe

[Jeffrey Holmes]

quote:

---

Originally posted by:

jbythesea

I asked Art to get some anhydrous and we used it with good result.

So, I think it works better, but I'm just not sure it's because it

removes moisture. I suspect that it causes something (glue or wood)

to swell/shrink just a tiny bit. It could be that it is able

penetrate and foul up the adhesion just enough to let the wedge

action work better. It could even be that by evaporating, it

cools the joint and sets up a stress. This is academic and I may

very well be wrong. It's just booze for thought.

--Joe

---

Good observation, Joe. Now I'm curious... Have to look into this...