Hard Drying Oil

[George O'Hanlon]

This is based upon a recipe for a drying oil that is prepared with tung oil, which imparts hardness and fast drying, but is not suitable for oil painting. Tung oil (also called China wood oil) was used as a coach varnish in the late 19th and early 20th centuries. In this formula, we've replaced the tung oil with Natural Pigments Epoxide Oil, which has qualities similar to tung oil. VM&P Naphtha is available from most hardware stores, but other solvents can be used in its place, such as mineral spirits, but you will have to increase the amount of solvent. VM&P Naphtha should be used with some caution with dried oil paintings, because it is an aggressive solvent.

Mix all ingredients in the order listed below. They can be mixed together at room temperature, but it will be found that they will incorporate easier when heated to about 90° C.

INGREDIENTS	PARTS
Epoxide Oil	25.0
Vacuum-Bodied Oil (Extra-High Viscosity)	20.0
Copal Varnish	9.8
VM&P Naphtha (CAS 64742-48-9)	45.0
Cobalt drier	0.2
	100.0

[Steve Ladd]

George
That was fast! Thanks.
How much more mineral spirits would be needed to substitute for the Naphtha? And could you explain the need for the additional ingredients other than epoxide oil? I thought that the EO could be used by itself as a drying oil.

[George O'Hanlon]

Ten to fifteen percent more mineral spirits should suffice. You could make this recipe without copal resins, but this resin increases the hardness of the dried film without sacrificing flexbility. If you omit the copal varnish, increase all other ingredients equally.

The cobalt drier ensures faster drying, but this could also be omitted from the recipe.

[Orp]

Hey, great! Recipe section.


That's a tough medium. I bet one could paint outdoor art with that.

What if I was to use Vac Oil Low Viscosity, raise the resin varnish level and lower the EO amount? Then I figure I could use Spike Oil as the solvent, wouldn't you think?

I guess then it would be a different animal, but I've been thinking of a resinous medium that could be used directly for white and then thinned slightly with the Spike for other colors if necessary. I haven't figured out the proportions yet, but I just feel there's a nice balance there if tweaked correctly. Not sure about the drier.

[Steve Ladd]

Orp

A couple of questions: couldn't Spike Oil be used as the solvent in the formula, even if the proportions weren't changed? ( I have some, but haven't tried it yet ). And, would you mix the more "resinous medium" with tube white, or did you mean to make white paint from powdered pigment? I was wondering about the thickness of the Vac Oil too, and like the sound of a low viscosity one.
I can see that I'm going to have to get a legitimate measuring cup for these mediums and ingredients; so far I've just been making divisions on the outside of an empty jar with a ruler and sharpie pen, but it's not sophisticated enough for extremely small proportions like .02% drier etc.

[Orp]

Hi Steve

Tubed since I won't make my own; even the Stack White I add back to complete the tubed White. I think one needs rollers to do White right (and tight).

I'm supposing Spike isn't strong enough to bust through Vac Oil IV and EO together easily which is why George's goes for the Naptha instead.

Steel measuring spoons here...

[George O'Hanlon]

Well, yes, there are probably a million variations possible of this recipe, but then you would end up with something completely different.

Steve, I do not recommend spike oil for several reasons; the most important being its slow evaporation rate. Another reason is its cost.

If you do not want to use VM&P Naphtha, then use odorless mineral spirits, or better yet a combination of the two.

Orp, you could use the low viscoity oil and reduce the amount of solvent, but I think the high viscosity works better in this recipe. The low viscosity lowers the viscosity of the medium and reduces its flow out and leveling quality.

This is a very fluid and fast drying medium, so do not let the names of the ingredients make you think it is something else!

[Steve Ladd]

George
I bought some Naphtha at the hardware store today and will give your formula a test whirl as soon as the Epoxide oil arrives next week.
About another possible recipe ingredient: Venetian Turpentine. I bought some of this stuff a couple of months ago, before doing enough research on it, and now wish I hadn't. It was touted as being a fast-drying balsam in some articles that I read, when in fact, it turns out to be a slow glossy drier. But I'm wondering if it still might be used for something, possibly even as an ingredient in a final varnish. Any thoughts?

[George O'Hanlon]

Originally posted by Steve Ladd:
Venetian Turpentine... I'm wondering if it still might be used for something, possibly even as an ingredient in a final varnish.

Do not use it as a final varnish. It may be used as a plasticizer in oil painting mediums, but it does not offer many advantages over a simple oil medium.

[anahlb23]

Good One . Thanks for the recipe.