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Baroque

Boiling walnut oil and resin - doesn't work

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Hi I have been trying to using walnut oil instead of linseed oil for a couple of reasons, and after trying several times, I am still having problems getting a varnish out of it.

 

I take 100 ml of resin, boil it at 170-190 degrees for 1 hr, then warm the walnut 20ml oil to the same temperature, and mix them together and keep them at boiling point for about half an hour. Then, after cooling to 120 degrees, I add warm turpentine, about 30 ml. The final product is not impressive, I get a thick and dense mass precipitating at the bottom - rather similar to tar, and a liquid phase  on top of it which never mixes with the dense part, which apparently never dries.

Did I boil too long or too short time, or too low temperature?

Any ideas?

 

Thank you!

Edited by Baroque

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 From what I’ve experienced, your temperatures are not high enough for the majority of your resinous constituents to bond with the oil. Abietic acid based resins have varying temperatures in which they will start to incorporate into the oil depending on how they are processed: it seems the higher the melting point of the resin, the higher the temperatures necessary to properly bind it with the oil. For resin that is not highly cooked, I’d suggest a temperature of 200 degrees CELCIUS held for a minimum of 3 hours. Less time, and you’re likely to have drying problems. As you get into varnish making, you’ll learn that you can adjust your times and temperatures depending on the state your resin and the state of your oil, whether it is bodied, raw, sun thickened, ect. With a highly cooked pine resin being combined with oil at 240 degrees Celsius, an hour is sufficient. If you find that you have a large percentage of precipitate upon cooling, and your varnish looks cloudy, Try to boost temperatures again. I would also reevaluate your oil to resin ratio. The most common varnishes hover at around 50:50  resin:oil by mass. A high resin(lean) oil varnish is good for use as a ground, where it is close to the wood, but they can be too hard and brittle for a main varnish. Heating oil and resin to these temperatures is dangerous. Be careful and think of your safety and health! 

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I too would suggest a higher temperature for combining the oil and resin, perhaps 250 C. If the temperature is not high enough to bond the oil and resin, a precipitate will form when solvent is added, forming a goo at the bottom of the container.

For the oil and resin to combine properly, it doesn't really matter how long this temperature is maintained, just that it is reached at least momentarily.

A quick way to determine whether the temperature has been high enough is to place a dab of the cooking varnish on a piece of glass, and see if it turns cloudy when the solvent is mixed in.

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16 minutes ago, David Burgess said:

I too would suggest a higher temperature for combining the oil and resin, perhaps 250 C. If the temperature is not high enough to bond the oil and resin, a precipitate will form when solvent is added.

For the oil and resin to combine properly, it doesn't really matter how long this temperature is maintained, just that it is reached at least momentarily.

A quick way to determine whether the temperature has been high enough is to place a dab of the cooking varnish on a piece of glass, and see if it turns cloudy when the solvent is mixed in.

 Good advice.

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You can probably still cook that varnish again to cook out the solvent and then add oil or resins into mix as necessary and boil to proper temperature and get good varnish.

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12 minutes ago, David Beard said:

If you aren't sure about what your doing, and where the danger points are, then just don't play arpund with cooking varnish.

Go buy some.

I never knew what I was doing until I tried it. After a lot of mistakes, I’m now having fun and success.

:)

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Hello Baroque.

I'd say your quantities are off. Try weighing your ingredients and shoot for a 1:1 ratio to begin. e.g. 100 g of prepared resin mixed with 100 g of oil.

As for heat - Look up FredN's comments on temp. When you see the surface foam up, the varnish has formed- as it cools you can add turpentine, or not. Also look up the Bass book by Roger Hargrave - he published a recipe for making a solvent free varnish.

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On 11/2/2019 at 10:56 AM, Baroque said:

Boiling walnut oil and resin - doesn't work

Depends on what you're using it for............  [Moves a cauldron closer to a "bretèche", and peers over the parapet.]  :ph34r::lol:

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1 hour ago, Urban Luthier said:

 prepared resin .

As for heat - Look up FredN's comments on temp. 

What is prepared resin?

Even Fred says one should fuse/crack the resin/rosin first.  I'll assume rosin/resin are the same for the time being.

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Colophony that has been pre cooked for colour - it is all in the Bass book.

Important part is weighing the ingredients. Baroque's experiment with 100ml of resin and 20ml of oil will result is a solid mass after cooling.  

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On 11/2/2019 at 2:56 PM, Baroque said:

Hi I have been trying to using walnut oil instead of linseed oil for a couple of reasons, and after trying several times, I am still having problems getting a varnish out of it.

 

I take 100 ml of resin, boil it at 170-190 degrees for 1 hr, then warm the walnut 20ml oil to the same temperature, and mix them together and keep them at boiling point for about half an hour. Then, after cooling to 120 degrees, I add warm turpentine, about 30 ml. The final product is not impressive, I get a thick and dense mass precipitating at the bottom - rather similar to tar, and a liquid phase  on top of it which never mixes with the dense part, which apparently never dries.

Did I boil too long or too short time, or too low temperature?

Any ideas?

 

Thank you!

Basically by heating the resin and oil together you made some kind of plastic that is insoluble in turpentine. It's a complete myth that resin and oil have to be heated together for hours to form some kind of magical bond. For centuries artists have been combining these mediums cold to make glazes with a view to proven longevity.

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1 hour ago, Melvin Goldsmith said:

Basically by heating the resin and oil together you made some kind of plastic that is insoluble in turpentine. It's a complete myth that resin and oil have to be heated together for hours to form some kind of magical bond. For centuries artists have been combining these mediums cold to make glazes with a view to proven longevity.

Is this how you make your varnish?

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2 hours ago, Melvin Goldsmith said:

Basically by heating the resin and oil together you made some kind of plastic that is insoluble in turpentine. It's a complete myth that resin and oil have to be heated together for hours to form some kind of magical bond. For centuries artists have been combining these mediums cold to make glazes with a view to proven longevity.

YES Thank you! it is possible that classical varnish wasn't formed (if that is the correct word) - just heated long enough to melt the two ingredients together. (need to look up the reference but i think it was Raymond white who referenced this)

 

Also for the fun of it one can try pulverizing dry (cooked colophony) and mull into linseed oil -- surpassingly one can actually make a serviceable varnish this way. Although it takes a long time to actually mull the colophony fine enough to clarify in the oil...

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On 11/2/2019 at 10:56 AM, Baroque said:

Hi I have been trying to using walnut oil instead of linseed oil for a couple of reasons, and after trying several times, I am still having problems getting a varnish out of it.

 

I take 100 ml of resin, boil it at 170-190 degrees for 1 hr, then warm the walnut 20ml oil to the same temperature, and mix them together and keep them at boiling point for about half an hour. Then, after cooling to 120 degrees, I add warm turpentine, about 30 ml. The final product is not impressive, I get a thick and dense mass precipitating at the bottom - rather similar to tar, and a liquid phase  on top of it which never mixes with the dense part, which apparently never dries.

Did I boil too long or too short time, or too low temperature?

Any ideas?

 

Thank you!

I notice that you do not indicate farenheit or centigrade degrees.  Be sure you know the difference.  The 250C is higher than 250F.

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@Baroque temperature aside, your primary issue is that  your quantities way are off.

There is simply no way to make a useful varnish from 20ml of oil and 100ml of resin. These quantities will give you what you got, a gooey clump of semi-solid tar that wont mix with your turpentine. Some guidance:

  • Read the Bass book by Roger Hargrave - starting at p121
  • Weigh your ingredients and go for 1:1 to start
  • It may be useful to start with larger quantities - keeping a consistent temperature with smaller quantities can be difficult 
  • You should not need to go over 200 C at any point to make a good solvent free varnish. As a point of reference here is a quote from the Bass book that refers to how the varnish ingredients may have been put together:
    • "The method(s) I used for combining these ingredients was based on two or three further snippets of in- formation. The first of these concerned the length of the colophony molecules. These were found not to have been significantly altered. Accordingly, White had concluded that the colophony had not been cooked at a high temperature. He suggested that it had probably been heated just hot enough and long enough to blend it with the oil and mastic. His conclusion about the mastic was that it had probably been added as plasticizer, last of all."
  • The Bass book and Gary Bease varnish making article published in the Strad should be required reading for anyone attempting to make thier own varnish

 

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20 hours ago, Michael_Molnar said:

Is this how you make your varnish?

Yes and no. I make varnishes for the different layers in different ways.  Generally I will pre treat my oil and resins and combine with minimal heat or no heat. Heating oil reduces it's brushing time and add's no color so I prefer to keep the oil ratio low and the brushability high.

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2 hours ago, Urban Luthier said:

There is simply no way to make a useful varnish from 20ml of oil and 100ml of resin. 

It appears baroque has lost all hope - hasn't posted anything since mid Nov.

Other than which recipe he's using the first thing to know is what kind of rosin/resin he is using.  Then try to determine if that type of material he has is soluble in the various liquid forms available like acetone, alcohol, whites spirits etc.

So to possible save what he did to make a varnish one could start with 350 ml of spirits of turpentine and blend it all together and let it set for about threes weeks minimum - longer would probably be better.

Question is should the pgst air out for the prescribed time of two to three months?  I know I'm not that patient and would be even less patient if I just possibly wasted 100 gr. of resin/rosin.  If he used that cheap goldey/yellow-greenish colophony he might be able to save face and have enough varnish for quite a few violins.

Or....................., instead of trying the above, simply give it all to sospiri and see what he can do with it.

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On 12/20/2019 at 8:16 AM, David Burgess said:

I too would suggest a higher temperature for combining the oil and resin, perhaps 250 C. If the temperature is not high enough to bond the oil and resin, a precipitate will form when solvent is added, forming a goo at the bottom of the container.

For the oil and resin to combine properly, it doesn't really matter how long this temperature is maintained, just that it is reached at least momentarily.

A quick way to determine whether the temperature has been high enough is to place a dab of the cooking varnish on a piece of glass, and see if it turns cloudy when the solvent is mixed in.

If I understand what you're saying correctly, seperation with the application of a solvent indicates the colophony/LO varnish is still a mixture compared to cooking at a temperature high enough for the colophony/LO to form a compound.  Aside from the reaction with a solvent (that I don't use), how would the mixture vs. compound properties vary? 

Thanks,

Jim

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2 hours ago, Jim Bress said:

If I understand what you're saying correctly, seperation with the application of a solvent indicates the colophony/LO varnish is still a mixture compared to cooking at a temperature high enough for the colophony/LO to form a compound. 

That's how I am interpreting it, so far. But it also depends on the solvent.  Xylene and acetone can deliver quite different outcomes from the many varieties of mineral spirits, and also from the many varieties of turpentines. And various combinations can deliver even more confusing outcomes.

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