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Larch Turpentine for making Varnish


xraymymind
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Hello folks,

Now that Strasbourg Turpentine is pretty much completely unavailable, I am considering using Larch turpentine instead to make a varnish with.

I wonder whether anybody here has used Larch Turpentine (Larch Balsam) to make an Oil Varnish?

If you have, I (and I'm sure many others here) would love to hear from you. How did it work once cooked properly, and then cooked with Linseed Oil? Is it sufficiently hard for a good varnish, what are the properties like, etc.?

Any advice on this would be very much appreciated.

 

(I know that many people use and like Colophony, but that is not what this thread is about - there is so much information about Colophony varnishes already out there, but very little about Larch Turpentine.)

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Just now, JacksonMaberry said:

Yep, it's great. Venice turpentine works beautifully too and is cheaper. Buy some, cook it for color and to drive off volatiles, incorporate it into oil, and enjoy 

Thanks so much for your quick reply, JacksonMaberry! That is very positive news to hear.

I know that in its raw state, Larch Turpentine has can be used as a plasticizer, for making varnishes softer. But, obviously it's properties will change after cooking. Do you find that once cooked the Larch varnish is hard enough for outer coats?

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1 minute ago, xraymymind said:

Thanks so much for your quick reply, JacksonMaberry! That is very positive news to hear.

I know that in its raw state, Larch Turpentine has can be used as a plasticizer, for making varnishes softer. But, obviously it's properties will change after cooking. Do you find that once cooked the Larch varnish is hard enough for outer coats?

Yes. The composition of all conifer resins is frankly very similar (though not the same) and the principal component is abietic acid. Expect it to behave very similarly to any other conifer resin varnish.

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I think that the main difference between larch turpentine and pine or fir or spruce turpentine is in acidity, which as far as I know the former is neutral while the others are more acidic. This is positive for the stability of the varnish, but less positive for color because it darkens less with cooking. Nice refractive index anyway, which makes it excellent for an illuminating ground on wood, but not very different in mechanical characteristics compared to the other colophony, including amber.

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41 minutes ago, xraymymind said:

Thank you again. Did you ever make varnish with Strasbourg Turpentine - if so, I wonder whether if the final effect (on the wood) was very similar to Larch?

Wishing you a good day.

I found them quite similar. The Strasbourg may have been a little redder, but that could have been the cooking. Any of these will need to be used with mulled pigments to get sufficient color without too great a thickness.

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5 hours ago, JacksonMaberry said:

Yes. The composition of all conifer resins is frankly very similar (though not the same) and the principal component is abietic acid. Expect it to behave very similarly to any other conifer resin varnish.

I wouldn't describe them as being all that similar. In my experience, I will agree with Sora about rosin behaving as if it is much more acidic, and will add that the rosin-based coatings I have experimented with deteriorated rather quickly.

Of course, I can't rule out that my rosin/oil varnish experiments contained some sort of major flaw, which I did and still do not realize.

In my experiments, I eventually got around to tempering the acidity by adding lime, but had already soured so much on rosin as a varnish component, that I never was motivated enough to follow it through to a full conclusion. Repeated tests on 10+year survival and "maintenace of property" rates are both time-consuming and expensive. Moved on to what I thought might be greener pastures.

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14 minutes ago, David Burgess said:

I wouldn't describe them as being all that similar. In my experience, I will agree with Sora about rosin behaving as if it is much more acidic, and will add that the rosin-based coatings I have experimented with deteriorated rather quickly.

Of course, I can't rule out that my rosin/oil varnish experiments contained some sort of major flaw, which I did and still do not realize.

In my experiments, I eventually got around to tempering the acidity by adding lime, but had already soured so much on rosin as a varnish component, that I never was motivated enough to follow it through to a full conclusion. Repeated tests on 10+year survival and "maintenace of property" rates are both time-consuming and expensive. Moved on to what I thought might be greener pastures.

Right, good points all around. I shouldn't have been so hasty - that was a pre coffee response. It's true that the main chemical constituent of all these resins is the same, but there are a lot of differences in the smaller constituents and that makes a difference. pH as you note and Davide did as well, is a biggie. 

Of all the resins I've cooked for a simple varnish (that is to say one resin and one oil), Larch seemed to me to produce the best results. 

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A few things.

If you go out looking to buy 'Venice Turpentine' these days you will in most cases be sold rosin thinned out with turpentine spirits.  For most commercial purposes that is what passes as Venice Turpentine these days.  So specifically buy Larch Balsam.

These material remains very mobile, even when you cook off the volatile components.  This persisting mobility is very good for clarity right at the wood surface and into the wood surface.  But, an out varnish with too much portion of VT may not be stable enough to hold a polish.

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2 minutes ago, David Beard said:

A few things.

If you go out looking to buy 'Venice Turpentine' these days you will in most cases be sold rosin thinned out with turpentine spirits.  For most commercial purposes that is what passes as Venice Turpentine these days.  So specifically buy Larch Balsam.

These material remains very mobile, even when you cook off the volatile components.  This persisting mobility is very good for clarity right at the wood surface and into the wood surface.  But, an out varnish with too much portion of VT may not be stable enough to hold a polish.

The composition of the Wood finishing Enterprises Venice turpentine is about half larch, with the other half being pine gum and spirit. It's really quite good. But yes, I too recommend getting their plain larch, but not the more expensive tirolean larch 

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On 8/2/2021 at 1:22 PM, Davide Sora said:

I think that the main difference between larch turpentine and pine or fir or spruce turpentine is in acidity, which as far as I know the former is neutral while the others are more acidic. This is positive for the stability of the varnish, but less positive for color because it darkens less with cooking. Nice refractive index anyway, which makes it excellent for an illuminating ground on wood, but not very different in mechanical characteristics compared to the other colophony, including amber.

David,

All spot on with one exception.   An acid neutral varnish made to build up a film will tend to wear differently than traditional varnishes.   As it is harder it will develop tiny scratches and not wear through much like terpene varnish.

on we go ,

Joe

 

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1 hour ago, joerobson said:

David,

All spot on with one exception.   An acid neutral varnish made to build up a film will tend to wear differently than traditional varnishes.   As it is harder it will develop tiny scratches and not wear through much like terpene varnish.

on we go ,

Joe

 

I have no elements to confirm or disprove your hypothesis, I have not much experience with varnishes made with larch rosin, mine were just general theoretical assumptions. However, Echard found larch resin in the varnish of the Stradivari "Sarasate", which seems to have a very respectable classic wear.:)

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7 minutes ago, Davide Sora said:

I have no elements to confirm or disprove your hypothesis, I have not much experience with varnishes made with larch rosin, mine were just general theoretical assumptions. However, Echard found larch resin in the varnish of the Stradivari "Sarasate", which seems to have a very respectable classic wear.:)

True.  It just takes a lot longer!

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On 8/2/2021 at 3:00 PM, David Burgess said:

In my experiments, I eventually got around to tempering the acidity by adding lime, but had already soured so much on rosin as a varnish component, that I never was motivated enough to follow it through to a full conclusion. Repeated tests on 10+year survival and "maintenace of property" rates are both time-consuming and expensive. Moved on to what I thought might be greener pastures.

Would it be revealing personal secrets if you were to disclose what kinds of things you discovered in those pastures? (I mean the things you found to use in varnish, not the things you accidentally stepped in.)

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5 hours ago, Davide Sora said:

I have no elements to confirm or disprove your hypothesis, I have not much experience with varnishes made with larch rosin, mine were just general theoretical assumptions. However, Echard found larch resin in the varnish of the Stradivari "Sarasate", which seems to have a very respectable classic wear.:)

What fraction of the varnish could be attributed to larch? Was it just a plasticizer like mastic?

 

 

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On 8/3/2021 at 1:53 PM, JacksonMaberry said:

The composition of the Wood finishing Enterprises Venice turpentine is about half larch, with the other half being pine gum and spirit. It's really quite good. But yes, I too recommend getting their plain larch, but not the more expensive tirolean larch 

How stable is the red color. Does it fade to orange?

 

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9 minutes ago, Michael_Molnar said:

How stable is the red color. Does it fade to orange?

 

Hi Mike, thanks for asking. I don't believe I have enough data to give you an answer that I would be satisfied with. Even cooking for extreme durations, while it does substantially deepen the color, doesn't provide as much color to a finished oil varnish as the rosinates I make, so I don't favor it for a true color varnish. Regarding the fastness of the red color induced by cooking, it appears to be quite stable, but I would want to collect more data over a longer period of time and exposure before saying anything definitive.b

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15 hours ago, Michael_Molnar said:

What fraction of the varnish could be attributed to larch? Was it just a plasticizer like mastic?

It seems to be a major constituent of the resinous fraction, but as usual, they are very cautious in stating it due to decomposition due to aging.

These are the excerpts from two of his relevant articles:

57249430_SarasateVarnishEchard1.thumb.jpg.963059ea6f7b64cd7818b787eb24bf21.jpg540481528_SarasatevarnishEchard2.thumb.jpg.11ca4a179c7af14566b3d842e8fafa60.jpg

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