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rjmjr
03-12-2002, 12:08 PM
Hi,

I inherited a tube of copper oil paint and am considering using some. However, the Gamblin website suggests metallic paint should not be thinned with turpentine. (Gamblin seems to have a bias toward not using turpentine at all - which I don't agree with)

Is there a reaction between turpentine and copper powder pigment? If so, what can be safely used to thin copper (metallic) oil paint? Can I use petroleum-based thinners? OMS? Also, I've read that copper pigment reacts (turns black) when combined with cadmium? I can't remember my source for this information, but is this true? If so, its yet another way to make black without using black! ;)

- Rob

paintfool
03-12-2002, 12:46 PM
I haven't used any oils with metallic pigments and infortunatley haven't found too much info on them at this point. Here's one thread to skim through:
http://www.wetcanvas.com/forums/showthread.php?s=&threadid=25549&highlight=metallic+pigments
Not terribly informative, but worth looking at. I'll continue to search for you.
Cheryl

Einion
03-12-2002, 03:15 PM
Rob are you sure the pigment is in fact copper powder? Most metallic paints are actually mixes of transparent pigments and coated mica flakes.

To answer your first question, I'm fairly certain there are no interactions between copper and turps, ditto with any suitable solvent. About the second query, like most generalisations this is only so useful, in this case it is misleading as it likely was in reference to Emerald Green (in use at the time of the introduction of the first cadmium yellows in the mid 19th century) which is not a stable pigment anyway. These days the phthalocyanine colours are almost all copper compounds and they are among the most stable of synthetic organic pigments and certainly don't react with cadmium colours.

If the paint is in fact made from copper, and made well, the grains will be protected by their coating of oil so in the short term it will be quite stable. In the long term however I would conjecture that with the drying of the paint, the copper will oxidise, turning reddish and eventually black over the years. Who knows, since dry oil films are water-permeable it may even allow the formation of verdigris which might make it greenish!

Einion

rjmjr
03-13-2002, 12:15 PM
Thanks for the info Einion, I was hoping you'd respond! :) The paint in question is "Gamblin Artist Colors" - Copper oil paint made with real copper powder as a pigment. For "metallic" oil paint, Gamblin seems to use metal powder for pigments instead of the mica flakes \ transparent pigment combination.

- Rob

belladonna
03-13-2002, 02:39 PM
Why do you want to use metallic pigments? They are pretty straight out of the tube but you cannot manipulate them as you can ordinary paints. They loose their metallic effect if you mix them with regular paints. They might be fine for small areas of detail, but not for large areas. (I was given a tube also but it was a huge disappointment.)

Copper and brass teapot Burnt sienna, Cad yellow light, Burnt umber, and White.

owens1299
03-13-2002, 02:54 PM
another place you might want to check with is stores that carry house paint or and interor designer... they use metallic pigments/paints all the time... and Im sure that they could tell you what you can mix/not mix with over the phone... or... if there is a local college with an art or theatre department... they might be able to tell you also...

Einion
03-15-2002, 02:14 PM
Super teapot belladonna! Burnt Sienna sure is a great choice for copper isn't it?

On the whole I agree about using metallic paints but they make for some interesting decorative elements within a picture if one likes that sort of effect.

Einion