Newbie Oil Questions -

[Yellow Ogre]

I have been painting in acrylics for 4 years and made the move over to oils last week while on a plein air vacation in Taos & Palo Duro Canyon. Love the flexibility in drying time. I started with inexpensive starter kit oils (Lucas and Urban Guerilla starter kits). Will move up to better paints when I exhaust my starter kit.

1) I am using odorless terps and a brush washer. I also bought mineral spirits. Can they be used in place of terps or are they just for final brush clean up?

2) I bought Liquin impasto to thicken up my paints - will this yellow?

3) I bought cobalt drier per salesperson recommendation. Any warnings?

[OOzOO]

I use odorless mineral spirits to thin down first washes, because it doesn't add oil (so it leaves the paint "lean") and it dries fast. I also have several mixes of medium that contain OMS as a drying agent, but not much. I don't recall the exact recipes now, but I don't think any of them contain more than 25% OMS, and most are more like 10%. Other than that, I keep a brush washer full of it to clean up after painting, but during painting I use safflower oil. You can use the OMS to clean between colors, but you have to make sure the brush is really dry afterward, or you'll effect the consistency and drying time of the next color you mix, so I use the oil instead, and just wipe the brush really well.

I'm afraid I can't help with the others. I found recipes I like for mediums, and mostly stick with them.

[sidbledsoe]

1-You can thin oil paints with some mineral spirits, as with any other medium, it can be problematic if used in excess.
2-I have only tested regular liquin, it didn't yellow at all.
3-Cobalt is a strong drier and using too much can be bad for the paint film, I have never tested it but it is well known that it can increase darkening/yellowing, etc. Here is a quote from AMIEN:

Cobalt driers are oxidation catalysts, drying the film from the top down -- this is not the way drying oils normally dry. Excessive amounts of drier can cause the paint films to wrinkle and yellow. Moreover, the cobalt drier itself can be unstable once exposed to air in the jar.
We therefore do not recommend the use of these kinds of accelerating driers in oil paints.

Searches here will turn up many threads discussing these topics at length.

[pmcnerney]

What is OMS?

[DAK723]

Originally Posted by pmcnerney

What is OMS?

Odorless Mineral Spirits

[pmcnerney]

Thank you for that. If I would have read it again i would have saw that. Is there a formula for drying oils. Such as 25% OMS 10% flax oil and then your oils. Or is it a guess. At this point for me it is a guess. I have been using Quick Dry. But I cant find it any more. I have used it in the past on a few paintings with good results.

[Crystal1]

There are all sorts of quick dry medium. Liquin is probably the most commonly used. Happy painting.