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Glue sizing as a ground?


polkat
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I've read about hide glue sizing as a ground, which seems pretty common to some builders, though I've never tried it. How does it stand up to other traditional grounds? And how is it mixed (extra water amount)? What would happen if other proteins (say...egg white) were mixed in? Anyone here do this?

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I've read about hide glue sizing as a ground, which seems pretty common to some builders, though I've never tried it. How does it stand up to other traditional grounds? And how is it mixed (extra water amount)? What would happen if other proteins (say...egg white) were mixed in? Anyone here do this?

polkat,

The sealing properties of glue sizing are good. This is a quick and relatively easy way to seal the instrument. Effective, as Mike says, as long as the varnish you are using sticks to it. The downside is a loss of depth and reflectivity.

on we go,

Joe

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Why not, the thin glue goes right into the wood and prevents the rosin oil sinking in too far, the Rosin oil forms a ground on which to varnish.

One advantage to using glue is that water based stain like tea and coffee can be used over it, before the ground goes on. Saves time compared to weeks in the tanning salon.

Note that the glue is not used as a ground but as a primer for the ground. The Rosin Oil ground lies partly in the wood and provides protection where varnish wears away.

Instead of glue one could use dewaxed shellac just as easily, I've used Gum Benzoin to seal the insides of the instrument, works quite nicely imparting a lustre to the wood, and smells nice.

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I've noticed that violins which use a hide glue size need a lot more care when you're using clamps to put a top back on or glue up a seam - if there's a slight touch of water under the cork of the clamp it will lift all the varnish off as it comes off! Disastrous.

This kind of size seems to be quite common with Mittenwald instruments ...

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Thanks for the ideas guys! For the last 10 years or so I have generally use vernice bianca alone as a sealer/ground under my varnish (oil), and have been quite satisfied with the results. However, I am an experimenter (dang me!), and have been looking for something simple and new to try. From what I've read, glue sizing has been an accepted (if less then desirable) ground, so it seemed like something to mess with. My plan was to try and find a way to add egg white to the glue sizing (looking at serious temp control), to introduce more protein.

Ben, I am wondering if Gum Benzoin could be used as a substitute for Gum Arabic in vernice bianca? Seems that gum arabic is getting a little hard to find (locally anyway).

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Vernice bianca is made in water because gum arabic is water soluble. But Benzoin is not very water soluble so you would have to use ethanol and this would be a problem with the egg white.

You can simply seal with some ethanol soluble resin like bezoin or shellac, or elemi etc... if you really want to seal with a resin.

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Martin, my mate Bob has a Klotz with that ugly black stuff lingering around the varnish, sounds good though.

'Glue size' is a thin concentration of glue used to size thngs like end blocks etc.

'Gelatin' is a very weak glue gone cold, the 'Old Wood' varnish application video reffers to it rather pretentiously as 'technical gelatin', when it's really just bloody weak glue. :mellow:

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I don't understand why you would use something water soluble. Why not use colorless varnish to seal? The only time I put glue on a curly maple test strip it killed the flame. Maybe I didn't thin the glue enough...

I have had very good results with both gelatin and clear varnish grounds. On one violin I used 2 coats Jello clear gelatin mixed thin as a ground, then Hammerl water stain and Hammerl colored oil varnish. On another violin I used clear Hammerl varnish with enough tripoli mixed in to make a paste, which I rubbed into the wood, then rubbed off, for a ground, then Hammerl colored varnish. On yet another violin I used a linseed oil/tripoli paste rubbed on and wiped off as a ground then colored Hammerl varnish. What flame there is shows well through each finish, the grain shows very clearly, and you can easily see the wood change color as you tilt it to different angles in the light. I like to see the light and dark areas change from one to the other as I tilt those violins (dichroism?). I'd have to say that the gelatin ground violin is the most beautiful, and its finish has the best clearness, but only by a very slight margin.

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The use of alum in sizes goes back at least to the Renaissance, if not before. If Strad's (etc. ... we always pick on Antonio) varnishing knowledge and supplies did indeed come from the art world, he would have know about alum in glue size. Of course, that doesn't prove... well, you know.

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I've used gelatin sealer with a bit of alum with good success under oil varnish. Gelatin is more refined (chemically speaking) than hide glue but otherwise similar. The addition of alum is said to make the protein set harder. I burnish with horsetail after the sealer has cured.

Doug

What would be the procedure for adding alum to hide glue or gelatin?

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What sort of Alum we talking about ?

"For the Freckles which one getteth by the heat of the Sun: Take a little Allom beaten small, temper amonst it a well brayed white of an egg, put it on a milde fire, stirring it always about that it wax not hard, and when it casteth up the scum, then it is enough, wherewith anoint the Freckles the space of three dayes: if you will defend your self that you get no Freckles on the face, then anoint your face with the whites of eggs." —Christopher Wirzung, General Practise of Physicke, 1654.

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