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Julian Cossmann Cooke

Spirit Varnish for the Convinced and the Curious

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43 minutes ago, violinsRus said:

Thanks Davide, my experience exactly.  I don't include spike lavender in any varnish anymore.  Others may have different experience...

I know at least one maker here in Cremona that use spike oil succesfully, but in oil varnish, perhaps may have a different behaviour. He makes a very beautiful amber varnish.

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Elemi is added to varnish as a faux plasticizer. I say faux because it does dry, over the course of years rather than months, and turns into a hard resin in the long run, after the check has cleared. In that, it would be similar to adding pine sap to your varnish. So it doesn't surprise me that a varnish with elemi would have drying problems.

I have never had problems with wax in shellac. Perhaps since elemi and wax are both turpentine soluble, the elemi and wax are combining, and the solvent in the elemi is keeping the wax soft.

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13 hours ago, Michael Darnton said:

Elemi is added to varnish as a faux plasticizer. I say faux because it does dry, over the course of years rather than months, and turns into a hard resin in the long run, after the check has cleared. In that, it would be similar to adding pine sap to your varnish. So it doesn't surprise me that a varnish with elemi would have drying problems.

I have never had problems with wax in shellac. Perhaps since elemi and wax are both turpentine soluble, the elemi and wax are combining, and the solvent in the elemi is keeping the wax soft.

I agree, many varnishes that contain essences (or oleoresins with essences inside them) will delay their hardening, but it is only a matter of time before they become hard and chippy. Maybe even the old ones were like that, who knows, but in their current state they are hard and chippy due to aging over the centuries. So what I expect from my varnish is to quickly become mature, so that you can correctly judge its acoustic effects (and therefore the sound of your violin) in a reasonable time after application, without having to wait years to understand its real qualities.

As for the elemi, one thing that has never been said in the recipes is that to avoid this problem (or limit it) it is necessary to melt it on the hot plate (in a water bath or under controlled temperature not to burn it) to evaporate the volatile components as much as possible.

I think that an acoustically functional varnish (not harmful) must be hard and therefore inevitably chippy, otherwise it would be easy to use an oil varnish with high oil ratios if you like a greater plasticity and softness (some paints of the painters go up to 1: 6 resin/oil ratio) while it seems that the Stradivarian ones are more close to almost the inverse ratio.

Then it seems that even linseed oil becomes hard over time, it is difficult to control this, with alcohol varnishes I think it is easier to control stabilization over time and more predictable .

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On 3/29/2020 at 5:20 AM, Davide Sora said:

As for the elemi, one thing that has never been said in the recipes is that to avoid this problem (or limit it) it is necessary to melt it on the hot plate (in a water bath or under controlled temperature not to burn it) to evaporate the volatile components as much as possible.

If you aren't using it as intended in the original (faulty) recipe, why use it at all?

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27 minutes ago, Michael Darnton said:

If you aren't using it as intended in the original (faulty) recipe, why use it at all?

You're right, in fact I eliminated it and replaced it with linoxin (but that's another story) because I don't like resins that contain essences out of control. But even after the heat treatment (at low temperature, just to melt it and make it liquid) it still remains a soft and waxy resin useful for the purpose. The final varnish will be just a bit harder, as it would become in any case after some years once the balsamic components of elemi slowly evaporate anyway. Same for spike oil, which is even worse for me.

Do you have any resin to replace the elemi to recommend? Or do you think it is better to follow the recipe of 1704 literally, spike oil included?

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If you are trying to soften a spirit varnish, a couple of drops of castor oil will do it. I don't know by experience if that is permanent, either, but don't see why it shouldn't be. It doesn't take much, and if you add too much the varnish gets progressively softer until it stays sticky. This was the original plasticizer for nitrocellulose lacquer, before polysyllabic synthetics took over that job, and it was recommended to me by one of the chemists at a company that made commercial lacquers.

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Thanks, I have never tried castor oil, but I will try to recommend it to anyone who will ask me for advice for a simple and easy to make violin varnish. Of course I will also ask them to keep me informed on how it will behave over the years, so I can use them as lab rats.:P

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11 minutes ago, Michael Darnton said:

I have been using it for 30 years, if that counts.

I would say it is an excellent guarantee that will not give problems, if used in the right quantities. :)

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Plasticisers and softeners in spirit varnish are pretty difficult topic. 

A very useful advice I took from a friend who is a chemist was: if you blend into a spirit varnish a substance which dries slowly, no matter what you combine with it, it will sooner or later dry out. 

(This does not apply to oil varnishes when ingredients are boiled and can polymerize in different degrees depending on cooking time and temperature.)

This tells all about balsams like copaiva etc. and makes the outcome incalculable in recipes. 

There are some ingredients however aiming at improving brush-ability like some etheric oils like spike lavender and so on, which, if amounts are properly adjusted to the necessary minimum, do a good service without damaging the proportions of the varnish.

if any softening agent for whatever goal is desired, bees wax is probably one of the best ingredients because it stays stable for thousands of years. (As archeologists have found out from graves in Egypt.) 

For elemi, it is somehow in between both extremes. (Liquid balsam and solid wax) From the beginning it is not liquid so the predictable changes are not too dramatic over time. I see this as the reason why 1704 can be used safely, but it seems that proper cooking is important to get the right consistency. (I once made 1704 which turned out to be still liquid after cooking, which was not good and ended its life in the garbage. It must become a soft paste comparable to a soft hand creme.) Elemi dries out in approximately 25 years. I bought some which I put away and after opening the jar 25 years later it was hard and brittle.)

Castor oil belongs to the group of non drying oils which says all. I think grape seed oil belongs to the same group. 

davide's use of dried linseed oil, or purified linoxyn is probably the better description of it, comes close to properties of wax because the oxidation process which would transform raw linseed oil in a varnish is anticipated before it is blended to varnish. 

So in summary, before I blend anything into a spirit varnish I make some research if it is really stable.

For ingredients which are not expected to form their final properties within a short time (like raw linseed oil) a procedure to fix the problem is absolutely necessary. 

 

 

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On 3/28/2020 at 1:04 PM, violinsRus said:

Thanks Davide, my experience exactly.  I don't include spike lavender in any varnish anymore.  Others may have different experience...

My antidote for the goopiness is more alcohol.  First, I thin what has cooled after cooking.  Then, when applying, I dip the brush in alcohol before each stroke and express it by dragging the brush over a rigid wire suspended over the varnish.  The alcohol added is just enough to keep the varnish thin enough to go on easily without running.  I keep the varnish warm on a coffee warmer as I apply it so periodically, I have to pour in a little alcohol to return the varnish to the consistency I want.  In the case of the photo of my local resin recipe, I don't think I thinned it quite enough.  It seems to behave differently from traditional 1704.

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7 hours ago, Andreas Preuss said:

Plasticisers and softeners in spirit varnish are pretty difficult topic. 

A very useful advice I took from a friend who is a chemist was: if you blend into a spirit varnish a substance which dries slowly, no matter what you combine with it, it will sooner or later dry out. 

(This does not apply to oil varnishes when ingredients are boiled and can polymerize in different degrees depending on cooking time and temperature.)

This tells all about balsams like copaiva etc. and makes the outcome incalculable in recipes. 

There are some ingredients however aiming at improving brush-ability like some etheric oils like spike lavender and so on, which, if amounts are properly adjusted to the necessary minimum, do a good service without damaging the proportions of the varnish.

if any softening agent for whatever goal is desired, bees wax is probably one of the best ingredients because it stays stable for thousands of years. (As archeologists have found out from graves in Egypt.) 

For elemi, it is somehow in between both extremes. (Liquid balsam and solid wax) From the beginning it is not liquid so the predictable changes are not too dramatic over time. I see this as the reason why 1704 can be used safely, but it seems that proper cooking is important to get the right consistency. (I once made 1704 which turned out to be still liquid after cooking, which was not good and ended its life in the garbage. It must become a soft paste comparable to a soft hand creme.) Elemi dries out in approximately 25 years. I bought some which I put away and after opening the jar 25 years later it was hard and brittle.)

Castor oil belongs to the group of non drying oils which says all. I think grape seed oil belongs to the same group. 

davide's use of dried linseed oil, or purified linoxyn is probably the better description of it, comes close to properties of wax because the oxidation process which would transform raw linseed oil in a varnish is anticipated before it is blended to varnish. 

So in summary, before I blend anything into a spirit varnish I make some research if it is really stable.

For ingredients which are not expected to form their final properties within a short time (like raw linseed oil) a procedure to fix the problem is absolutely necessary.

I agree.

I would add propolis among the possible plasticizers for alcohol varnishes, but always with the risk of putting too much and ending up with too thermoplastic varnish (don't ask me why I know ....).

Anyway, I think is better to remove the beeswax and the balms it contains so as to get a resin with a more predictable behavior.

Besides, I don't like waxes for the loss of transparency they cause.

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1 hour ago, Davide Sora said:

I agree.

I would add propolis among the possible plasticizers for alcohol varnishes, but always with the risk of putting too much and ending up with too thermoplastic varnish (don't ask me why I know ....).

[....]

Besides, I don't like waxes for the loss of transparency they cause.

Yep, Davide, forgot propolis. 

Propolis unless freed of non drying ingredients is just not to be used in spirit varnish. (And who would bother to buy an expensive soxhlet apparatus plus the necessary super explosive benzene ether to do it? In the past actually I did. :P)

For wax, yes they disturb transparency. Depends on the ratio anyway. I found a slight cloudiness in a yellow varnish always interesting. But that's a matter of taste. 

 

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On 4/20/2020 at 10:51 AM, Andreas Preuss said:

Yep, Davide, forgot propolis. 

Propolis unless freed of non drying ingredients is just not to be used in spirit varnish. (And who would bother to buy an expensive soxhlet apparatus plus the necessary super explosive benzene ether to do it? In the past actually I did. :P)

For wax, yes they disturb transparency. Depends on the ratio anyway. I found a slight cloudiness in a yellow varnish always interesting. But that's a matter of taste. 

 

I have followed a method for removing wax from propolis that seems to work well in terms of the mechanical properties of the resulting resin.  (Happy to translate the instructions and post here if folks are interested.)  That said, I only use it in a tincture right now to add some color to my shellac sealer.  My guess is that it would be fine in that form in spirit varnish.  But in that dilute solution, it is questionable that it adds anything meaningful.

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Many years ago a friend who used propolis told me that the easiest way to purify it was to dissolve it in alcohol and let it settle, as long as possible, ideally a couple of years. I've had 2 gallons of it settling for 25 years, but I don't use it, so I don't know how it works.

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16 hours ago, Julian Cossmann Cooke said:

I have followed a method for removing wax from propolis that seems to work well in terms of the mechanical properties of the resulting resin.  (Happy to translate the instructions and post here if folks are interested.)  That said, I only use it in a tincture right now to add some color to my shellac sealer.  My guess is that it would be fine in that form in spirit varnish.  But in that dilute solution, it is questionable that it adds anything meaningful.

Several decades ago some books and articles on propolis varnishes were written, someone claimed that it was part of Stradivari's varnish so it had become fashionable. I fell in the trap for some time, and I had found a system of extraction (don't remember where) with petroleum ether that worked very well, it only dissolves the resin and everything else settle out to the bottom. I still have propolis left from those times and I'd be curious to know your system, you never know, petroleum ether is not something you find in the shop on the street corner....

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I have been experimenting with spirit varnishes lately. I bought some Copal resin and tried to dissolve it in Methylated spirits - without success.

Some of it dossolved but the are balck particle suspended in the jar and a gooey residue at the bottom.

Does it have to be a specific type of Copal to make spirit varnish?

I also have Sandarac beads which I intend to dissolve in Isoproanol.

I'm just starting out with all these different resins wherea previously I just used shellac flakes and even the ready mixed button shellac.

Can someone confirm that Methylated spirits (the purple stuff) is essentially Isopropanol with a dye added to stop you from drinking it.

 

Michael.

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On 5/23/2020 at 5:06 PM, Special Agent Ransac said:

I have been experimenting with spirit varnishes lately. I bought some Copal resin and tried to dissolve it in Methylated spirits - without success.

Some of it dossolved but the are balck particle suspended in the jar and a gooey residue at the bottom.

Does it have to be a specific type of Copal to make spirit varnish?

I also have Sandarac beads which I intend to dissolve in Isoproanol.

I'm just starting out with all these different resins wherea previously I just used shellac flakes and even the ready mixed button shellac.

Can someone confirm that Methylated spirits (the purple stuff) is essentially Isopropanol with a dye added to stop you from drinking it.

 

Michael.

As far as I know, the only alcohol-soluble copal is the Manila copal, which is not a fossil resin like the other copals.

I think that Methylated spirits is ethyl alcohol, which is of plant origin,  while Isopropanol is Isopropyl alcohol, which is of mineral origin (from petroleum).

The purple color is given by an added substance, it is better to avoid using purple alcohol because it adds a not nice synthetic color to your final varnish. The best thing you can do is to use pure food grade ethyl alcohol (Everclear) because it is the least toxic and the one that works best. As a cheaper alternative I would stay on isopropyl alcohol, it works but is more toxic than Everclear.

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On 5/25/2020 at 6:25 AM, Davide Sora said:

As far as I know, the only alcohol-soluble copal is the Manila copal, which is not a fossil resin like the other copals.

I think that Methylated spirits is ethyl alcohol, which is of plant origin,  while Isopropanol is Isopropyl alcohol, which is of mineral origin (from petroleum).

The purple color is given by an added substance, it is better to avoid using purple alcohol because it adds a not nice synthetic color to your final varnish. The best thing you can do is to use pure food grade ethyl alcohol (Everclear) because it is the least toxic and the one that works best. As a cheaper alternative I would stay on isopropyl alcohol, it works but is more toxic than Everclear.

The good news on the Everclear front is that you may be able to find one of the off brands which here in TX save you about 33%.

 

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Depending on where it is from, Copal is only partially soluble in alcohol. This makes it a challenging choice to use in spirit varnishes.

Shellac flakes and ethyl alcohol (grain alcohol) create a basic varnish that is durable, clear, and can be polished to a smooth finish.

But it can be a bit "soft", both visually and to the touch. 

Sandarac is a traditional additive for shellac varnishes to increase the hardness. It is soluble in alcohol.

Anything added beyond this is just being fussy, IMO. One would do better to practice various application techniques rather than looking for some magic ingredient to make the varnish trivial to apply, and dry to a perfect finish.

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If you have the opposite experience with sandarac, I would like to hear about it. The concoctions I experimented with tended to dry hard and brittle as a spirit varnish. Maybe you are confusing it with Elemi, another alcohol soluble resin that seems to be used to soften varnishes, especially those containing sandarac.

 

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I percieve shellac as harder and tougher than sandarac. Sandarac may seem hard in the raw beads. But in thin applications, I'd call it brittle, not "hard" as you did. So I believe it adds brittleness to shellac which is more coherent (tough/hard) without sandarac. Maybe "brittle" is opposite of "soft" in your vocabulary? Not in mine. (But I'm norwegian; not english.)

I share your minimalism regarding ingredients. I use mastix to soften shellac. I think mastix soften the shellack without adding brittleness. Or expressed another way: it adds plyability to the shellac.

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