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Goran74

Any possible colophony varnish receipt without use of heat?

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Hello,

I would like to know if there are especially colophony varnish recipes that do not use heat (for us who live in cities and apartments). Possible solutions will be with alcohol or distilled turpentine. I cooked many times varnish (colophony, linseed oil etc) but smell, smoke are too much for neighbors (and wife). Linseed oil can managed just by washing and sun. 

Thanks

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I successfully dissolved some cooked rosin in alcohol and applied it as a spirit varnish. It didn't have any more desirable properties than shellac so I never pursued it further. I can't recall if I built up a thick film with it or not, but I'd expect it to be brittle without a plasticizer.

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I once tried to make spirit varnish using colophony but without success.The varnish was brittle and sticky, I also tried to add a bit of damar which is partially soluble in alcohol but without any success either. 

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An alcohol varnish with only rosin would be too fragile and inconsistent, it is not recommended. You can make a varnish with rosin dissolved in turpentine (essence varnish), but in any case it would be better to use cooked rosin to avoid stickiness.

I don't think it would be a very good violin varnish but I have never tried it, maybe you could give it a try, essence varnishes have been used in the past by some luthiers. Moreover, recipes for this type of varnish (essence varnish) are found quite easily in ancient manuscripts because they were used as a final varnish on oil paintings. Mastic and rosin was the resins more frequently used.

These varnish are treated quite thoroughly in A. Tolbeque's book "L'Art du luthier".

I only used something similar as ground on the wood, that does not form a layer and is then covered with other varnish. This way it works really well as a refractive ground.

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I've had good success with 3 part rosin, 1 part boiled linseed oil dissolved in turpentine, but this always requires heating, if proper precautions are made, most importantly to work outside with fire extinguisher close by, it isn't really that hard to do. The varnish is slow drying and may need direct sunlight to dry quickly, but it is an excellent varnish tonally, and judging from what we know about the ingredients found in Stradivari varnish, possibly even the genuine article, the colouring is the difficult part, and is more of a mystery.

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@Goran74 as far as I know the only violin varnish that can be made with colophony without heating it, is Michelman's varnish.

The problem with colophony, it' s that this resin is too acidic and has too low melting point. converting it into rosinate can be made in two ways. one is by heating colophony with a chemical like quicklime and this was the method used in the beginnings of the modern varnish industry.

a better way is to convert colophony to rosinate by dissolving it in an alkaline solution and precipitating it with a salt solution (alum, zinc sulphate etc.). This method allowed industry to produce many kinds of inks for printing.

cold-processed rosinates are more pure, more chemically neutral and stable that the equivalent heat-processed ones (temperature around 270 °C is necessary). 

Joseph Michelman used this process for his varnish recipe (rosinate+linseed oil+turps) and in my opinion this can be a nice ground varnish.

When I was in Cremona, I was taught by a Ukrainian maker a clever way to use Michelman's varnish as a ground. mix varnish for two coats and apply the first one lightly. when the first coat will be dry (one or two days) the varnish left in the container will have turned into a gel. use this gel to rub into the wood and fill the pores then let it dry thoroughly.

colophony in spirit varnish: as Davide said, colophony is too brittle -- avoid it in s.v. recipes. But you can add a little Venetian Turpentine in spirit varnish. It makes it more tough and improves adherence to wood. I learned this from my teacher, Alessandro Voltini.

 

 

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Thank you all for your answers. 

21 hours ago, Davide Sora said:

These varnish are treated quite thoroughly in A. Tolbeque's book "L'Art du luthier".

Mr David thank you for the suggestion. I know the book but did not have pay attention to that varnish. 

5 hours ago, Giovanni Corazzol said:

colophony without heating it, is Michelman's varnish.

Mr Giovanni, thank you too. I know Michelman s recipes. I have to say that I admire him as researcher, even I am not fan of his recipes.

Why do I have to convert the resin? Last days I was thinking the known Marciana varnish, with just melting the ingredients, and adding drier - Pb3O4. That means: Raw linseed (just washed), colophony (pine), mastic and Pb3O4 (or another type of lead oxide). Then I can add some color (dissolved in turpentine). So, the use of heat would be minimum, without fumes etc. Question is how much drier should I add. Once, a Marciana bottle I had, some way became solid in 3 days. Such way, I solve the problem with fumes etc, the problem of drying and the problem of color. 

Such way I see no reason to cook the varnish for hours and turn the resin black. 

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There seems to be no practical way to make a colophony/oil varnish without heating. The challenge is that colophony and linseed oil will not fully incorporate with each other without being heated together at about 120C (250F) for two hours. The temperature and heating times can be varied a bit depending on the proportion of colophony to oil, but 120C/2hr should be good for up to 2 pats colophony, 1 part oil by weight.

Colophony will readily dissolve in alcohol, but you may encounter problems with its dried finish if you do not melt it first to drive off volatile compounds. So you are back to the problem of heating a smelly chemical. You might be able to buy pre-melted colophony which would avoid that problem.

I've experimented with colophony/shellac mixtures to get a harder varnish, but I decided a pure shellac finish had good enough wear properties for a violin or viola.

 

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3 hours ago, ctanzio said:

will not fully incorporate with each other without being heated together at about 120C (250F) for two hours

I prefer my short cooked (3-4 minutes) varnishes regarding fragility and wear. Prior to that I cook the colophony and oil separately. I think a perfect "incorporation" of the oil is mainly needed if you want to varnish a boat. At least I don't fear the wear of my varnish, as long as it looks nice. Too long "incorporation" or cooking time also means worse brushability, especially in short oil varnishes. 

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3 hours ago, Michael Szyper said:

I prefer my short cooked (3-4 minutes) varnishes regarding fragility and wear. Prior to that I cook the colophony and oil separately. I think a perfect "incorporation" of the oil is mainly needed if you want to varnish a boat. At least I don't fear the wear of my varnish, as long as it looks nice. Too long "incorporation" or cooking time also means worse brushability, especially in short oil varnishes. 

In your experience does the 'incorporation' time affect the drying time of the varnish?

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15 hours ago, ctanzio said:

There seems to be no practical way to make a colophony/oil varnish without heating. The challenge is that colophony and linseed oil will not fully incorporate with each other without being heated together at about 120C (250F) for two hours.

 

How do you know when the resin and oil are fully incorporated (or not)?

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7 hours ago, J.DiLisio said:

In your experience does the 'incorporation' time affect the drying time of the varnish?

The cooking temperature and time of the oil + resin mix influence strongly the viscosity, therefore the drying time is also influenced. I can't tell if it is due to faster chemical oil polymerization or simply due to the viscosity. 

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21 hours ago, Bodacious Cowboy said:

How do you know when the resin and oil are fully incorporated (or not)?

Resin and oil will form a solution from the start, which means the resin molecules are evenly dispersed throughout the oil but not "attached" to the oil molecules. As the solution cools/hardens, the resin comes out of the solution.

The purpose of heating the solution for an extended period of time is to provide enough energy for the resin and oil molecules to bond with each other. How long and what temperature is a complicated question and requires a technical understanding of the reaction that is not really needed for practical application. But in general, the 250F/2hr rule is good enough for the range of resin to oil mixtures one is likely to find useful for a varnish.

Heating it for a longer period of time results in the oil/varnish mixture forming more complex chains of molecules, higher viscosity and shorter drying time. At some point, the structure of the molecules begins to dramatically alter and the varnish becomes darker and the color more intense. A 250F/2hr varnish will have very little color beyond what the resin and oil initially had, but heating it at that temperature for an extended period of time usually yields a varnish that will color nicely.

There is some debate as to whether one should use higher temperatures to get a darker varnish, but I think one runs into the danger of causing the resin/oil to decompose and become darker because of an increase of opaque elements due to the decomposition.

This is a bit off-topic from the original question. I think cooked oil varnish is best left to professionals who have the know-how and facilities to make it safely. 

 

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On 7/27/2020 at 1:30 PM, Goran74 said:

Hello,

I would like to know if there are especially colophony varnish recipes that do not use heat (for us who live in cities and apartments). Possible solutions will be with alcohol or distilled turpentine. I cooked many times varnish (colophony, linseed oil etc) but smell, smoke are too much for neighbors (and wife). Linseed oil can managed just by washing and sun. 

Thanks

You can mix oil rosin and turpentine if you keep the oil to rosin ratio high. You can still get the advantages of both the oil and the rosin if you do it this way. No cooking involved and easy to apply and dry in small amounts.

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2 hours ago, sospiri said:

You can mix oil rosin and turpentine if you keep the oil to rosin ratio high. You can still get the advantages of both the oil and the rosin if you do it this way. No cooking involved and easy to apply and dry in small amounts.

How long does this take to combine cold?  
What ratios would you recommend exactly?

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21 hours ago, ctanzio said:

 

This is a bit off-topic from the original question. I think cooked oil varnish is best left to professionals who have the know-how and facilities to make it safely. 

 

I would have to respectfully disagree. I don't find it really that hard to make a useable cooked oil varnish. I made a batch on my first try with little to no experience or knowledge and it worked out. 

Some basic safety precautions/common sense will go a long way when doing the cooking. 

But. Perhaps I had some beginner's luck. 

I do agree that varnish making is probably best left to pros in that to really perfect it takes an enormous time and resource investment that hobbyists might not find palatable. 

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On 8/1/2020 at 6:44 PM, J.DiLisio said:

How long does this take to combine cold?  
What ratios would you recommend exactly?

The oil turpentine and rosin combine almost instantly. The ratio of oil to rosin is about one to four.

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