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joerobson
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To all the varnish makers out there.

This is the time of year that I get lots of calls from players and makers.   The subject: case print varnish.

To avoid this issue in your work here is a test.   On a hot sunny day place a chunk of your resin in an aluminum foil pan in the direct sun.  The chunk should have a nice sheer and defined edges.   If the sun and temperature melt the resin or even round off the edges of the chunk, your varnish is likely to case print.

on we go,

Joe

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7 hours ago, joerobson said:

To all the varnish makers out there.

This is the time of year that I get lots of calls from players and makers.   The subject: case print varnish.

To avoid this issue in your work here is a test.   On a hot sunny day place a chunk of your resin in an aluminum foil pan in the direct sun.  The chunk should have a nice sheer and defined edges.   If the sun and temperature melt the resin or even round off the edges of the chunk, your varnish is likely to case print.

on we go,

Joe

are certain resins more prone than others? mastic,copal, amber?

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7 hours ago, jezzupe said:

are certain resins more prone than others? mastic,copal, amber?

The harder the resin the less prone to heat degradation.  Amber being the hardest one in violin use.  As most violin varnishes are made from some form of pine resin/colophony these are the most vulnerable.

on we go,

Joe

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3 hours ago, joerobson said:

The harder the resin the less prone to heat degradation.  Amber being the hardest one in violin use.  As most violin varnishes are made from some form of pine resin/colophony these are the most vulnerable.

on we go,

Joe

Very interesting. Where do cooked down Larch Turpentine or Strasbourg Turpentine stand on the hardness scale (with Amber being the hardest)?

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4 hours ago, joerobson said:

Just the resin.

do "We" {science} know why some resins of the same type are more heat stable than others? or is it more like good wood vs bad, just kinda luck of the draw based on various trees producing better saps than others based on variable weather and soil conditions? 

So I think the thing to get out of this, and I certainly trust your kernels of truth about such things, is that 1. test your resin before using it, and 2. because "you" are getting it from sources who are getting it in bulk , that batches can have variation and to not expect a supplier to know the intimate details about their resins, and that "this batch" , even though the same thing from the same supplier might not act the same way as one before...which circles back to number 1 

good tip to know, never heard it before 
 

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4 hours ago, xraymymind said:

Very interesting. Where do cooked down Larch Turpentine or Strasbourg Turpentine stand on the hardness scale (with Amber being the hardest)?

In general, the longer you cook a resin, or the higher the temperature at which you cook it, the more resistant it will be to melting or softening at higher temperatures. I have measured and confirmed this for both pine rosin and larch.

I would prefer to do Joe's test in an oven with a temperature readout, than in a piece of aluminum foil in the sun, where the temperature could be all over the place.

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38 minutes ago, David Burgess said:

In general, the longer you cook a resin, or the higher the temperature at which you cook it, the more resistant it will be to melting or softening at higher temperatures. I have measured and confirmed this for both pine rosin and larch.

My findings agree.

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On 8/30/2021 at 10:59 PM, David Burgess said:

In general, the longer you cook a resin, or the higher the temperature at which you cook it, the more resistant it will be to melting or softening at higher temperatures. I have measured and confirmed this for both pine rosin and larch.

 

On 8/28/2021 at 12:29 AM, D. Piolle said:

 

4- Both of those contain larixyl acetate which is a wonderful plasticizer and typical from the larch. That could give the dried film a really good resistance and resilience, unless it has been  cooked too hot (over 220°c if remember well ) or too long, and then get destroyed.

 

Hello,

High temperature but not too high and not too long, is that right?

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  • 2 weeks later...

The way the resin is cooked and also many other factors have an influence on thermo-sensitivity. .  Slacked lime is supposed to increase the heat resistance of the resin, as some of you already know...

in old codex(manuscripts) one can read very often about the cooking : " low and slow".

In my humble opinion, if one doesn't wash the oil, it could also make the varnish to remain (a bit) sticky, especially in warm weather.

Of course the quality of the oil, the way it has been extracted, are important factors as well. 

Too much of a drier could also damage the oil and actually be bad for the polymerisation. At first the varnish dries and then get sticky in a little while.

All that is actually not always easy to control.And to be honest, I find it hard to get certainty and draw a solid conclusion.

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13 hours ago, Michael_Molnar said:

Washing the oil removes waxes that are indeed sticky. However, I think most of us use clean, washed oil. Hope I’m not being presumptuous. :D

 

Not all , unfortunately...

There are still people who think that cooking the oil is sufficient. Just because it's written " pure" or  " for artistic purpose  " on the container.

There are also people that prefer to buy their varnish, which is actually fine.

And actually it seemed to be the rule years ago.

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30 minutes ago, D. Piolle said:

Not all , unfortunately...

There are still people who think that cooking the oil is sufficient. Just because it's written " pure" or  " for artistic purpose  " on the container.

There are also people that prefer to buy their varnish, which is actually fine.

And actually it seemed to be the rule years ago.

Right. Artists have no issue with a little wax in their oil.

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12 hours ago, Michael Szyper said:

How can wax be removed by washing with water?

The Strad published an article. It explains in few pictures. Put oil in a bottle, put same amount of water. Shake. Wait 24hours. Then 3 phases show up. Only the top one (oil) must me used. The middle is wax, the bottom is water.

In my first project I did not perform this step. Maybe it explains why my varnish seems sticky. I wonder how to remove wax or to correct it once it is applied.

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8 hours ago, Michael Szyper said:

How can wax be removed by washing with water?

 

4 hours ago, David A.T. said:

The Strad published an article. It explains in few pictures. Put oil in a bottle, put same amount of water. Shake. Wait 24hours. Then 3 phase show up. Only the top one (oil) must me used. The middle is wax, the bottom is water.

In my first project I did not perform this step. Maybe it explains why my varnish seems sticky. I wonder how to remove wax or to correct it once it is applied.

Add coarse sand to the water and oil mix. Shake like hell. Let it sit for 10 minutes. Pour off the clean oil.

 

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11 hours ago, David A.T. said:

The Strad published an article. It explains in few pictures. Put oil in a bottle, put same amount of water. Shake. Wait 24hours. Then 3 phases show up. Only the top one (oil) must me used. The middle is wax, the bottom is water.

In my first project I did not perform this step. Maybe it explains why my varnish seems sticky. I wonder how to remove wax or to correct it once it is applied.

 

7 hours ago, Michael_Molnar said:

 

Add coarse sand to the water and oil mix. Shake like hell. Let it sit for 10 minutes. Pour off the clean oil.

 

I know how to wash oil.

my question was rather how you would explain that you can bind a hydrophobic substance like wax by water and wash it out. For my understanding this is not possible. By washing oil you remove phospholipids. Stickiness of varnish is rather caused by misconception of your cook than by inappropriate washing.

10 hours ago, Melvin Goldsmith said:

What kind of varnish are we trying to make?....A boat varnish?

If you wish to replicate the incredibly fragile and delicate nature of the Old Italian varnishes you must embrace the natural falabilty of the ingredients you consider

dito

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