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Goran74

My Colophony varnish does not dry off

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Hello. I made some Colophony - Marciana's varnish as proposed "Giovanni" (and I thank him a lot) member here in maestronet (in an older post I had) with the following parts: 3 parts linseed oil (you can see the link for the oil I used - Winsor). Then 2 parts of colophony and 1 part mastic. I used it on different sealers: 1) shellac 2) colophony very diluted in alcohol. I have not tested it with plaster yet. When I dilute the varnish with turpentine (again Winsor) it dries in some hours very nice. So, do I have to use it diluted with turpentine or something goes wrong?

Also, does anyone know if the sealer of diluted colophony-alcohol cracks after time?

Thank you very much all for your time

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The original Marciana varnish is 2 parts oil, one part mastic, one part colophony, as the original recipe kept in the Marciana Library, Venice:

"Togli per una misura: una libra d'olio di linseme, et quocilo come si fà in una pignatta invetriata netta, poi vi metti su mesa libbra di pece greca chiara et bella et polverizzata et mesta quando la metti, tanto che si incorpori bene a fuoco dolce, poi vi metti su mezza libra di mastice macinato, et quando lo metti perché ei rigonfia leverai però la pignata da fuoco et mettilo su a poco a poco mestando et incorporando bene, poi torna la pignata al fuoco et mesta tanto che si solva ogni cosa bene, poi mettivi quanto una noce di allume di roccha arso pesto et mesta che si solva et incorpori bene poi lievala dal fuoco et colala per peza lina vecchia et serbala, et per legname, et per ferro et per carta et corame et per ogni dipintura et lavoro farà un opera bellissima et per stare alla aqua, et quando ti pare soda stempera con olio di lino come si fa etc. ".

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31 minutes ago, Goran74 said:

Hello. I made some Colophony - Marciana's varnish as proposed "Giovanni" (and I thank him a lot) member here in maestronet (in an older post I had) with the following parts: 3 parts linseed oil (you can see the link for the oil I used - Winsor). Then 2 parts of colophony and 1 part mastic. I used it on different sealers: 1) shellac 2) colophony very diluted in alcohol. I have not tested it with plaster yet. When I dilute the varnish with turpentine (again Winsor) it dries in some hours very nice. So, do I have to use it diluted with turpentine or something goes wrong?

Also, does anyone know if the sealer of diluted colophony-alcohol cracks after time?

Thank you very much all for your time

I use a 1:1 linseed oil to resin (Hargrave recipe) without solvents.  It has a long open time and dries well, but only under UV.  It is thick enough that I have to apply with fingers to get on a thin layer.  Using turpentine is not an option for me.

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2 minutes ago, Edward Byler said:

Hi Jim ! Could you explain not wanting to use turpentine? Thanks !

Nothing to do with the varnish.  The fumes make me ill.

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47 minutes ago, MANFIO said:

2 parts oil, one part mastic, one part colophony,

Thank you for your response. I have the Italian text and the translation, but I made a small variation with less mastic and more colophony. I read also with interest your numerous posts about this receipt. I found that you use the same diluted varnish as a sealer in a post, but when I did the same, the wood was soaking unequally to the wood (the known effect when oil goes to wood). So, do y have any suggestion for the sealer? Again thank you

22 minutes ago, Jim Bress said:

I use a 1:1 linseed oil to resin (Hargrave recipe) without solvents.  It has a long open time and dries well, but only under UV.  It is thick enough that I have to apply with fingers to get on a thin layer.  Using turpentine is not an option for me.

Thank you Jim. I do not have UV, I just use the natural light, tea etc. So, it seems to take a lot of time to dry.

 

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10 hours ago, Jim Bress said:

I use a 1:1 linseed oil to resin (Hargrave recipe) without solvents.  It has a long open time and dries well, but only under UV.  It is thick enough that I have to apply with fingers to get on a thin layer.  Using turpentine is not an option for me.

Why not use a respirator? 

 

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13 hours ago, Anthony Panke said:

How thick are your coats? 

Does it work if you use very thin coats?

Thanks for your question. I applied a thin coat with a brush, but not diluted. I applied diluted with turpentine and it dries fast. I don't know if the sealer is proper, because maybe the colophony over colophony delays process.

7 hours ago, CSchabbon said:

Why not use a respirator? 

I used turpentine till now. What other choices do I have? Thank you a lot

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18 hours ago, Jim Bress said:

Nothing to do with the varnish.  The fumes make me ill.

That's a shame. I think it has a pleasant scent. 

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8 hours ago, CSchabbon said:

Why not use a respirator? 

 

Over the course of a 20 year period working with solvents on a daily bases I became hyper sensitive to solvents of carbon chain lengths generally in the C-7 to C-14 range.  Even short exposures can make me very ill for a period of time (depending on length and concentration of exposure).  It would be foolish for me to store these chemicals in my shop (basement) or even use them outside with a respirator when I have viable alternatives, such as the spirit varnish Nathan has mention in another thread that I have had good success with.  There are also a couple of manufacturers that produce solvent free oil varnishes.  However, I prefer to make my own because then I really know whats in it.

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5 minutes ago, Nick Allen said:

That's a shame. I think it has a pleasant scent. 

Only if you have functional olfactory glands.  I do not.  Yes, I can still taste. :)

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On 4/25/2019 at 7:03 PM, Goran74 said:

Hello. I made some Colophony - Marciana's varnish as proposed "Giovanni" (and I thank him a lot) member here in maestronet (in an older post I had) with the following parts: 3 parts linseed oil (you can see the link for the oil I used - Winsor). Then 2 parts of colophony and 1 part mastic. I used it on different sealers: 1) shellac 2) colophony very diluted in alcohol. I have not tested it with plaster yet. When I dilute the varnish with turpentine (again Winsor) it dries in some hours very nice. So, do I have to use it diluted with turpentine or something goes wrong?

Also, does anyone know if the sealer of diluted colophony-alcohol cracks after time?

Thank you very much all for your time

Hi, Goran74! I am aware that the original Biblioteca Marciana manuscript has a different recipe. In my own one, I just wanted to reduce mastic in favor of the more strongly colored ( by heat processing) colophony.

I can tell you about my experience with pine resin varnish. Some important things I learned come from this forum. The information can be found in different threads, but I have no "bookmarks" for them at the moment.

(1) I believe that some problems in my first varnish batches were caused by colophony.

Simple colophony (turpentine distillation by-product) can be used to make varnish but, I was advised from other makers who make their own, that starting from raw pine resin can give a better result. In any case, I believe that pine resin should be heat processed at a temperature around 250 °C. Temperature should stay under 300 °C to prevent colophony becoming insoluble in oils (this was confirmed by J. M. Lozano in his varnish workshop). The heat processing should give a resin that, once completely cooled does not take fingerprints if you hold a piece in your hand, and it should have a hard, vitreous fracture.

I believe that my first batches did not dry well because I didn't pay attention to this.

I made the recipe I gave to you in the other thread, in 2012. I still have a jar of it. The pine resin that I used  came from Greece; a friend got it at a local company where colophony is processed for the food industry (I believe it is collected as a flavouring substance for wines). We cooked this raw (solid, pale amber) resin  at about 250-270°C before using for making varnish. Cooking reduced the resin about 20%.

In 2016, I made another batch of oil varnish with a friend from Switzerland.  We used another kind of resin, the Strasbourg turpentine (Kremer Pigmente, catalogue #62040).  Strasbourg turpentine is collected from silver fir (I must check this one) -- it takes a dark, nice color by heat processing. We had a loss of about 60% on the raw material because Strasbourg turpentine has a high content of balsam oil. First, we let the volatile oils go away at a lower temperature then rised up to about 230 °C.

These two varnishes dry well and are more or less the same in resin:oil ratio (around 1:1) For me, both resins are OK and have a nice color.

(2) another source of problems for me, was the spirits of turpentine. I was used to thin the varnish by adding about 20% spirits of turpentine to the (cooled down) varnish just after cooking. David Burgess advised me to stop doing that. I will see if I can find that thread. Spirits of turpentine can make the varnish unstable, because it can react with varnish in an unpredictable way. My varnish seemed just OK but, after some time I found it was very hard to brush. I tried  to thin it down to a good brushing consistency with different kinds of essential oils, but it didn't work so well. You can give Odorless paint thinner (like the "Sans-Odor"  by Winsor & Newton) a try; it can be an easy to find alternative, and it has been tested by some people I know in Cremona.

Anyway, if you add spirits of turpentine or another essential oil as a brushing agent, I believe you should use a minimal quantity. If you put too much, the varnish will likely make bubbles in the UV box. Thinned varnish is also less tough and can scratch off.

I think that if varnish can be brushed easily, by adding just some drops of thinner (mineral spirits) or no thinner at all, it is just perfect. If it's too thick, you can try to warm it a little (it works well) or, you can make another batch with a different resin:oil ratio.

(3) I remember discussing a colophony-based ground with my teachers and some friends in Cremona. It was some years ago... (around 2000-2001)

Some makers were used to prepare colophony by heating it to a rather high temperature, to darken it and use it as a ground. My teacher stated that this was a frequent cause of developing a craquelure (of a peculiar, distinctive pattern) in varnish. We saw an instrument from the Triennale collection, with that kind of craquelure pattern. In more recent times, rosin oil (a colophony distillate) was introduced as a refractive ground. You may want to use a modern product for this, and get more detailed instructions directly from the maker.

I hope this helps, there is a lot of information on The Pegbox, scattered here and there, it takes some patience to go through different threads and take notes, but I think that it's worth it. Or, better buy a commercial varnish? If I had more commissions, I would seriously think about it...

--Giovanni

 

 


 

 

 

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Hi Giovanni- very knowledgeable response; I'm curious to know the procedure where rosin becomes  insoluble in oil. I've made many runs and never experienced that. fred

 

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8 hours ago, FredN said:

Hi Giovanni- very knowledgeable response; I'm curious to know the procedure where rosin becomes  insoluble in oil. I've made many runs and never experienced that. fred

 

I've had that issue when cooking the colophony too hot. 

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This is one reason why Hargrave’s recipe and notes are worth following. He cooks the colophony very slowly at low heat and gets good results. Another thing to consider is using less oil. The oil dilutes the colour, so a lean varnish will be more intense, allowing for thinner layers. It also antiques very easily. 

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11 hours ago, Giovanni Corazzol said:

Hi, Goran74! I am aware that the original Biblioteca Marciana manuscript has a different recipe. In my own one, I just wanted to reduce mastic in favor of the more strongly colored ( by heat processing) colophony...

I have no words to thank you for your interest and for your time. That was some very valuable information for me. I use Greek resin too and I will seriously think about using painter's thinner-drier. It was proposed by a painter friend I had but I never tried it.

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21 hours ago, Giovanni Corazzol said:

(3) I remember discussing a colophony-based ground with my teachers and some friends in Cremona. It was some years ago... (around 2000-2001)

Some makers were used to prepare colophony by heating it to a rather high temperature, to darken it and use it as a ground. My teacher stated that this was a frequent cause of developing a craquelure (of a peculiar, distinctive pattern) in varnish. We saw an instrument from the Triennale collection, with that kind of craquelure pattern.

Hi Giovanni,

do you mind to say who your teacher was and what instrument of the Triennale are you talking about?

Just to get a better idea of what you mean.

If you do mind,   no problem.

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Hi Door Mouse,  from my experience  getting close to the cook becoming insoluble is optimal, but it is the oil that becomes insoluble in the mix.  I've never had rosin by itself become insoluble. Appreciate any description on procedures that create this condition.  fred

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On 4/28/2019 at 7:50 PM, Davide Sora said:

Hi Giovanni,

do you mind to say who your teacher was and what instrument of the Triennale are you talking about?

Just to get a better idea of what you mean.

If you do mind,   no problem.

Hello Davide, I think I got this information from Primo Pistoni and Alessandro Voltini.

They mentioned the use of heated colophony as a varnish ground and said that it was used by many makers in the past. But, we didn't make or use it in Alessandro's workshop. I don't remember exactly which instrument had the feature I was referring to, but it definitely was one of the oldest. Our discussion happened on an occasion I had to see the collection while Alessandro was retouching some of the instruments, as he was in charge of their maintenance at that time.

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I know that burnt rosin is insoluble. I have seen that. It is essentially carbon.

I also had a difficult time dissolving cooked FF rosin, but I never confirmed this.

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I think many makers know that a varnish that never dries is one that was undercooked and failed to get some cross-linking underway. Slow drying varnishes can sometimes be corrected with a chemical drier. 

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33 minutes ago, Michael_Molnar said:

I think many makers know that a varnish that never dries is one that was undercooked and failed to get some cross-linking underway. Slow drying varnishes can sometimes be corrected with a chemical drier. 

My varnish will pass the thumb print test right at six weeks.  Then a bridge can go on.   If what Goran did as compared to mine he needs a few more weeks.  Then if still not dry then I'd guess first too much oil.  I haven't really paid attention to what he exactly did to make his.  I can barely keep up with myself memory wise.  

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On 5/19/2019 at 11:41 PM, Giovanni Corazzol said:

Hello Davide, I think I got this information from Primo Pistoni and Alessandro Voltini.

They mentioned the use of heated colophony as a varnish ground and said that it was used by many makers in the past. But, we didn't make or use it in Alessandro's workshop. I don't remember exactly which instrument had the feature I was referring to, but it definitely was one of the oldest. Our discussion happened on an occasion I had to see the collection while Alessandro was retouching some of the instruments, as he was in charge of their maintenance at that time.

Hi Giovanni,

thanks for your answer. 

Not just an instrument made bad jokes with the varnish after winning the gold medal:lol:

Perhaps they were talking about Balzarini's cello whose varnish cracked badly shortly after the medal, but the fault was more likely the massive doses of UV on the finished instrument, dried too quickly in the hurry to deliver to the competition.:P

 

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