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wellerwilliams

aged turpentine

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A friend gave me a can of gum spirits of turpentine she'd kept in her garage for about 15 years. I poured it into a glass jar and have been exposing it to sunlight for several months. It's a deep brown color and slightly viscous. Painted on a glass plate, it dries in a day. Any ideas on how to use it in varnish without going through the cooking process?

ww

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A friend gave me a can of gum spirits of turpentine she'd kept in her garage for about 15 years. I poured it into a glass jar and have been exposing it to sunlight for several months. It's a deep brown color and slightly viscous. Painted on a glass plate, it dries in a day. Any ideas on how to use it in varnish without going through the cooking process?

ww

ww,

Put a drop on a glass plate. Tip it so that the drop runs down the plate. Set the plate in the sun. If the run dries out and hardens up in a couple days, the material is OK to use.

on we go,

Joe

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ww,

Put a drop on a glass plate. Tip it so that the drop runs down the plate. Set the plate in the sun. If the run dries out and hardens up in a couple days, the material is OK to use.

on we go,

Joe

Thanks Joe,

I think it does that. I'm going to see now if it will dissolve mastic for a cold varnish a la Michael Darnton. The color is very good, however I can't yet post an image.

ww

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Thanks Joe,

I think it does that. I'm going to see now if it will dissolve mastic for a cold varnish a la Michael Darnton. The color is very good, however I can't yet post an image.

ww

Likely it will dissolve the mastic, but the varnish will be slow to dry.

Joe

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Likely it will dissolve the mastic, but the varnish will be slow to dry.

Joe

I agree that it might be slow to dry. The mastic varnish on the cello I completed 2 months ago is just now stable, however I really like the "feel" of the varnish (not sure how to define that in other terms.)

ww

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The mastic varnish on the cello I completed 2 months ago is just now stable, however I really like the "feel" of the varnish (not sure how to define that in other terms.)

ww

Interesting, I made my first batch of oil varnish with mastic in the formulation a few weeks ago and was thinking it a little soft, but it's hardening, and I like the feel and looks, so tested mixing it up with some other harder varnish, it worked, but doesn't look quite as good, now you got me thinking, maybe I just need to be patient?

Back to the thread....I buy turps in a can, empty to a glass bottle, saved a few cans, a little left on the botom of the cans after a while the stuff gets dark, is that safe to color stuff or is just reacted garbage?

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I think to remember that the proportion of mastic:oil of M. Darnton varnish changed. In the PDF available it is 1:1, but on few maestronet threads about this varnish the ratio was more like 2:1 or 3:1 (mastic:oil)?

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Interesting, I made my first batch of oil varnish with mastic in the formulation a few weeks ago and was thinking it a little soft, but it's hardening, and I like the feel and looks, so tested mixing it up with some other harder varnish, it worked, but doesn't look quite as good, now you got me thinking, maybe I just need to be patient?

Back to the thread....I buy turps in a can, empty to a glass bottle, saved a few cans, a little left on the botom of the cans after a while the stuff gets dark, is that safe to color stuff or is just reacted garbage?

Re: being patient, which I'm not, I think this varnish is worth the wait. The quality is in the texture, and the way it seems to cling to the ground.

ww

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Interesting, I made my first batch of oil varnish with mastic in the formulation a few weeks ago and was thinking it a little soft, but it's hardening, and I like the feel and looks, so tested mixing it up with some other harder varnish, it worked, but doesn't look quite as good, now you got me thinking, maybe I just need to be patient?

Back to the thread....I buy turps in a can, empty to a glass bottle, saved a few cans, a little left on the botom of the cans after a while the stuff gets dark, is that safe to color stuff or is just reacted garbage?

Should be ok. May dry slower

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Likely it will dissolve the mastic, but the varnish will be slow to dry.

Joe

It did dissolve the mastic. I added linseed oil (about 40%) and the varnish dries in two days on a glass plate in the sun. However, the rich color of the turps is now quite dilute, of course, because of the mastic and the oil. I'm going to let it sit because I haven't finished the viola I'm working on yet.

Weller

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I made the Darnton mastic varnish following the instructions in the PDF noted above it turned out as he said it would. Essentially adding linseed oil in a weight equal to the mastic I started with.

My eye is still developing but, I find this varnish very attractive, easy to work and dries in 24hrs w/ UV exposure. What I'd like to know from those in the know is:

1) How does the mastic react with the linseed oil? Is the mastic simply suspended in the linseed oil or does the resin actually bond chemically with the oil? Given that the mixture changes from being very cloudy to very clear after the oil is added, I'm wondering if there is a chemical reaction

2) I hear nasty things about mastic varnish failure -- any experience with this recipe varnish and failure? Michael says no, but If it does some of the nasty things we see in Joshua Reynolds paintings happens that wouldnt be half bad in my books!

Chris

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2) I hear nasty things about mastic varnish failure -- any experience with this recipe varnish and failure? Michael says no, but If it does some of the nasty things we see in Joshua Reynolds paintings happens that wouldnt be half bad in my books!

Chris

I'm curious about what happened to the Reynolds paintings. Was the mastic in his painting medium

or in the picture varnish? It might make a difference. I know a painting conservator, and perhaps he has something on it.

Weller

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This is from the Tate Museum website about the restoration of a Reynolds painting.

"An initial solution of varnish was applied with a brush, in exactly the same way artists have been applying varnish for centuries (fig 1). A varnish is made by dissolving a resin in solvents like turpentine or white spirit. After application, the solvent evaporates leaving a hard, transparent, glossy film of resin on the surface. As well as saturating the paint surface, this first varnish provides a reversible protective layer over the original paint.

Traditionally, artists have used natural resins made from tree sap for varnishing, such as mastic. Chosen for their high gloss and easy handling with a brush, natural resins have a significant drawback: they become significantly yellow and more difficult to remove within 50 years. To avoid this, conservators frequently use synthetic resins which have been specially formulated for increased physical and chemical stability. The polycyclohexanone resin MS2A, developed for use in conservation, was used to varnish Lord Ligonier (fig.20. The MS2A resin should remain clear, transparent and easy to remove for at least 100 years in gallery conditions.

The paint surface of Lord Ligonier 1760 has a network of tiny cracks that have developed owing to age, drying problems and past treatments. The MS2A varnish, which has a small molecular size, was absorbed into this crack pattern in many areas, leaving the surface with matt patches, a problem known as ‘sinking’. To even out the gloss, a different varnish was applied using a spray gun (fig. 3). The acrylic resin B72 was used, as it is a stable polymer with long chain molecules, ideal for creating an even surface. The large resin molecules remain on the surface of the paint, physically unable to fit into the voids in the microscopic surface texture (fig 4)."

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i was tongue and cheek about the Reynolds painting. He apparently used a medium often referred to as meglip which contains mastic and linseed oil and a whole lot of lead as a dryer. Which led to some nasty effects. I think there is an article by raymond White kicking around which talks about the use of mastic varnish in painting

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This is really more about oil painting, since we generally don't use jelly mediums.

From jamescgroves.com

Linseed oil and Megilp

The potential problem with megilp and other thixotropic mediums is this: all jelly mediums, when added to basic oil paint, fool the artist into thinking his/her paint is suitably thick and rich in pigment when it is often not truly so. The paint merely appears properly thick due to the thixotropic and up-standing character of the jelly medium. Of course, linseed oil does not exhibit its eventual yellowing property until its first-to-dry outer layer reaches a certain stage or degree of oxidation /drying. And so the artist has no way -- fresh appearance-wise -- to judge if his paint has been over-dosed with linseed oil by use of a thixotropic agent such as megilp or wax, or bentonite, or aluminum stearate, or aluminum hydrate. Nay, but that fiendish surprise will occur 'down the road'.

Again, it is linseed oil that causes the primary yellowing /wrinkling of oil paint. It simply turns yellow when that eventual drying state is reached. This inherent malady cannot be stopped, though I will inform others herein that there are a few agents, like wax or standoil, which initially appear to stop it ; but this is merely due to a slowing of the drying state. Eventually, the linseed film still "gets there"... then it yellows ...and, when applied in thick layers, it also browns and wrinkles.

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