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MikeC

What's a good copal varnish recipe?

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i've always tought this as an interesting recipe - not cooked, never tried it, but I probably will, copal varnishes interest me a lot.

Colourless Varnish with Copal. —To prepare this varnish the copal must be picked; each piece is broken, and a drop of rosemary-oil poured on it. Those pieces which, on contact with the oil, become soft are the ones used. The pieces being selected, they are ground and passed through a sieve, being reduced to a fine powder. It is then placed in a glass, and a corresponding volume of rosemary-oil poured over it; the mixture is then stirred for a few minutes until it is transformed into a thick liquor. It is then left to rest for two hours, when a few drops of rectified 91alcohol are added, and intimately mixed. Repeat the operation until the varnish is of a sufficient consistency; leave the rest for a few days, and decant the clear. This varnish can be applied to wood and metals (Journal of Applied Chemistry).

Bitmead, Richard. French Polishing and Enamelling (A Practical Work of Instruction) (p. 58) - 1910

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rosmary oil? I wonder if it is anything like the lavender oil of my recipe. I couldn't put a drop of oil on each piece that I have. each piece is only about the size of a drop. it would take for ever.

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I purchased this copal because I wanted to try the recipe and this was cheap because it was discontinued, a pound for $5.95. I wrote back to them and asked what kind it is and this is the reply.

Thank you for your inquiry about our Gum Copal. This product has been discontinued for some time however, we do have some stock on hand. Our material comes from Australia, The Philippines or The West Indies and is a fossil resin. Unfortunately this is about all I know about this product.

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Very cool books but there is a danger of being completely distracted and spending the rest of your life chasing ephemera. Keep in mind that basically violin varnish was found to contain two ingredients, oil (linseed or walnut) and pine resin.

Varnish making and research should be regulated by the DEA as being highly addictive. You've been warned ! :blink:

Oded

AMEN.

on we go,

Joe

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rosmary oil? I wonder if it is anything like the lavender oil of my recipe. I couldn't put a drop of oil on each piece that I have. each piece is only about the size of a drop. it would take for ever.


You are right It would be hard to get the correct measurement, I would try using this....biggrin.gif
 

post-41255-0-75648700-1318497567_thumb.jpg

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I mixed some of this copal with denatured alcohol today and it dissolved pretty quickly. It has a pale yellow color but it goes on colorless in a thin film like blond shellac. Haven't tried to make an oil varnish out of it yet.

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sounds like manila copal. as a 'rule of thumb' if it dissolves in alcohol it's not likely to dissolve in oil.

Again, the 'rule of thumb' is that 'like dissolves like', alcohol is a highly polar molecule while oil is non polar.

There are some exceptions.

Oded

list of polar molecules where you'll find alcohol.

see also discussion of polarity under solubility in wikipedia

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Why ruin my fun? John Masters suggested this. :D

This blender is suggested by the manufacturer for mixing "stir-in pigments." They make a special preparation of transparent iron oxide powder for stirring in. I don't have this blender, so I haven't been successful at the stir-in.

Drat, I couldn't get the blender image to attach. See post #24 by Molnar.

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sounds like manila copal. as a 'rule of thumb' if it dissolves in alcohol it's not likely to dissolve in oil.

Again, the 'rule of thumb' is that 'like dissolves like', alcohol is a highly polar molecule while oil is non polar.

There are some exceptions.

Oded

list of polar molecules where you'll find alcohol.

see also discussion of polarity under solubility in wikipedia

So then this particular resin may not work with the old recipe I found (post 1) since it calls for dissolving in oil of lavender

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Where does NZ Kauri resin fit in, in terms of varnish-making? Is it a Copal resin, or something else? I have a chunk (half the size of my fist, I guess) that my Dad picked up while he lived in NZ, but I don't know what to do with it.

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Where does NZ Kauri resin fit in, in terms of varnish-making? Is it a Copal resin, or something else? I have a chunk (half the size of my fist, I guess) that my Dad picked up while he lived in NZ, but I don't know what to do with it.


smile.gif

...the term " copal,'* originally confined to the resin which the Arabs carried to Bombay and Calcutta....
.....Copal: Definition, —Commercially the term " copal " is not, nowadays, specifically restricted or solely applied to East African copal, but is used in a comprehensive way to group as it were under one commercial genus or species several widely distributed and more or less well or ill-defined resins having one main if not sole character in common, that of being capable of being used in the manufacture of oil varnishes.....
...... " Copal" means therefore commercially nothing more nor less than an oil-varnish resin.....
......(1) The hard copal clas^ include the true copals of the East Coast of Africa, typical of which is Zanzibar copal (also termed East Indian anime, Bombay copal, Calcutta copal). Other varieties of East African true copal are Mozambique copal and Madagascar copal........
......these three classes or groups only the copals ranked in class (1), derived from species of Trachylohium^ are capable of being regarded scientifically as true copals.....


.....At one time only the very hard copals were available for oil varnish-making, and when the first lots of Kauri were put upon the market they could not find purchasers, but when their value was recognised they rose so enormously in price that the best kinds of Kauri eventually fetched prices higher than even Zanzibar copal. In Great Britain Kauri was much appreciated, and was very extensively used, long before Continental varnish-makers had come to regard it with favour......
......Of late, varnish-makers on the Continent have used large quantities of Manilla copal, a resin of a similar botanical, but not geographical, origin as Kauri, but British varnish-makers prefer Kauri to Manilla. Clarke, in fact, regards Manilla as quite unsuitable for oil varnish-making.......
......So far back as 1870 Vincent, in a lecture before the Society of Arts, drew attention to the good and bad quahties of Kauri oil varnish. He more especially pointed out that if it yielded a very glossy and durable varnish for indoor work, it was not so very suitable for out-of-door application, as it did not withstand the weather very well.....
......The resin flows abundantly from incisions made on trees now growing.It is perfectly white, and so soft as to be used by the Maoris for chewing.....
.....There are thus three main varieties of Kauri to be differentiated— fossil, bush, and recent.


M'Intosh, John Geddes; Livache, Achille. The manufacture of varnishes and kindred industries based on and including the "Drying oils and varnishes" of Ach. Livache - 1908
wink.gif

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Well--what I have is either fossil or bush, I suppose...it is hard as a rock. Guess I will have to do some research and figure out how to use it. I wish Dad were still around to enjoy the result.

He did really enjoy the violins I made before he died. I remember him, in tears, listening to a duet of "Puff the Magic Dragon". It wasn't the quality of playing (good or bad), I think, but just that it was a song from his past, and a son and grandson playing for him, on instruments the son had made.

He'd be especially pleased to know that some resin he found on a hike would become the varnish on a violin.

Thanks.

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Well--what I have is either fossil or bush, I suppose...it is hard as a rock. Guess I will have to do some research and figure out how to use it. I wish Dad were still around to enjoy the result.

He did really enjoy the violins I made before he died. I remember him, in tears, listening to a duet of "Puff the Magic Dragon". It wasn't the quality of playing (good or bad), I think, but just that it was a song from his past, and a son and grandson playing for him, on instruments the son had made.

He'd be especially pleased to know that some resin he found on a hike would become the varnish on a violin.

Thanks.

Great history, thanks for sharing, I wish I could help you some, but my varnish experience is limited to 2 tung oil varnishes that I cook (for the interior of our floating home, shellacs, spirits and the modern stuff) built by dad's hands, I do the best I can, he is happy about it, we share a little of the same kind of good vibes. (I'm not a violin maker, only a happy salt)

I love to read, so have been reading one varnish book after the other, kindle is great . The one above I really like because of the history in it. There are lots of details on Kauri, the areas in NZ collected, I find it interesting.

I've posted the link before, here it is again.

http://openlibrary.o...dred_industrie

Beautifull violins. I like the dolphin inspired ideas, they are wonderful, saw many today, have been coming around a lot lately, always make everyone smile smile.gif.

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I've been experimenting a little with what i think must be manila copal - although I'd love a "test" so help me identify it.

What is interesting; it half-dissolves in alcohol and leaves a white powdery slurry.

But I discovered that in naptha/shellite/lighter fluid, it dissolves completely and well.

When brushed onto glass, the alcohol version leaves a slightly translucent film, stays sticky for a while.

The shellite version, on the other hand, dries in about 30 seconds, leaves a perfectly clear film, and hardens nicely.

Has anyone else used this solvent in touch-up varnishes?

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There seem to be a lot of different resins that are called copal. Mine dissolved almost completely in alcohol with only a few bits of dark residue. I didn't try it on glass but I will tonight. On wood it seems completely transparent

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i've always tought this as an interesting recipe - not cooked, never tried it, but I probably will, copal varnishes interest me a lot.

Colourless Varnish with Copal. —To prepare this varnish the copal must be picked; each piece is broken, and a drop of rosemary-oil poured on it. Those pieces which, on contact with the oil, become soft are the ones used. The pieces being selected, they are ground and passed through a sieve, being reduced to a fine powder. It is then placed in a glass, and a corresponding volume of rosemary-oil poured over it; the mixture is then stirred for a few minutes until it is transformed into a thick liquor. It is then left to rest for two hours, when a few drops of rectified 91alcohol are added, and intimately mixed. Repeat the operation until the varnish is of a sufficient consistency; leave the rest for a few days, and decant the clear. This varnish can be applied to wood and metals (Journal of Applied Chemistry).

Bitmead, Richard. French Polishing and Enamelling (A Practical Work of Instruction) (p. 58) - 1910

I have bought some viscous copaiba balsam directly from the Amazon, waiting to arrive, want to try it mixed in my ground.....I'm not a violin maker, but the stuff I've been doing is highly influenced by the violin community, many thanks. smile.gif

Found the same in this work of dubious provenance.

post-59554-0-23968500-1400560391_thumb.jpg

post-59554-0-84219300-1400560569_thumb.jpg

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I've mentioned this before (earlier in this old thread in fact)... Manilla Copal is soluble in alcohol.  As the only resin, it's quite clear but very shiny and a bit brittle (chips easily).

 

The filler (crack fill) varnish I make and use is Manilla copal (around 60% or so) with the remainder being a good quality sandarac and a small amount of light shellac.  I've also tried mastic, if very good quality, in substitution of the shellac.  I do add a little plasticizer as well, but only enough to make the varnish workable (not too chip-py).  I'll leave the choice of plasticizer to you.

 

I also occasionally use a little Manilla copal in retouch varnish, but at a much lower %.  More Sandarac, more light shellac, more plasticizer.

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Very cool books but there is a danger of being completely distracted and spending the rest of your life chasing ephemera. Keep in mind that basically violin varnish was found to contain two ingredients, oil (linseed or walnut) and pine resin.

Varnish making and research should be regulated by the DEA as being highly addictive. You've been warned ! blink.gif

Oded

 

Very cool books but there is a danger of being completely distracted and spending the rest of your life chasing ephemera. Keep in mind that basically violin varnish was found to contain two ingredients, oil (linseed or walnut) and pine resin.

Varnish making and research should be regulated by the DEA as being highly addictive. You've been warned ! blink.gif

Oded

I gave up chasing Ephemera when I met my wife.  :lol:

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is your copal crack fill varnish you use, do you make it fresh each time, or does it have a shelf life? thanks 

 

It has a very reasonable shelf life if properly stored when not in use.

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I struggled through the process of learning how to  make a varnish with fossil Congo copal varnish, one of the hard copals requiring cracking/depolymerizing before it is soluble in oil. The group of copal resins called Recent are distinguished by being soluble in alcohol because they are relatively young in time and have not been oxidized to the degree of the group called Fossil. Commercial copal varnishes  around Strad's time did not add  rosin which I think most amateur makers use, for it makes it a lot easier to start the melt of the copal. The shape of the container is also important. If you are in a super market check the jars of olives, the one that says Manzilla Sliced pieces is the ratio of height to width used in early Varnish Houses. The height is needed to reduce the loss of resin as it is heated to  temp's around 620-30oF, loss is still around 25%. Adding a piece of lead that melts at this range helps staying staying in the cracking range . Also a jacket from a cut down tin can around the lower portion is vital to keep it hot and prevent the resin from crawling up and sticking to the relatively cool sides. You recognize when the resin is cracked by an unusual change from much gassing and swelling to a motionless serene shiny black  fluid that a closer look shows there is rapid  boiling of the fluid. Oil is added and  cooked in until you can touch it and get a string around 8", or watch for a crater formation on top which is far more reliable than a string, I think. As Oded stated in an earlier post  making copal is a dangerous addiction.  fred

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I am having trouble in running Manila Copal, thought I had run it, let it harden, crushed it but it would not dissolve in linseedoil. 

It does not half smoke, will have another go but would appreciate some tips. 

You can keep reading books but in the end you have to be hands on, no other way. 

Jacob

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On 10/12/2011 at 3:28 PM, Oded Kishony said:

I would guess that he's doing this for his emulsions. Normally varnishes don't need that much stirring.

OK

You can use a brush in bowl to make emulsions.  What is wanted is a lot of shear involved.  Brushes are fine for this,  and you can use the same brush and bowel to apply if you want to try brushing emulsiond.

I point out once more that you must mix beyond the point of inversion if you want to go from water-in-oil (w/0) to o/w.  These are completely different.  The emulsion becomes quite thick just before inversion,  like a Dairy Queen ice cream.

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