Can conventional oils be mixed with Water Soluble Oils?

As per Winsor & Newton:

"Artisan Oil Colours and Mediums can be mixed with conventional oil colours and conventional mediums. However, the resultant mixture will be progressively less water mixable, the more conventional oil colour or oil colour mediums are used. We recommend using Artisan colours and mediums exclusively in order to benefit from the use of water instead of solvents."

It's hard to say for certain since it's proprietary information, but it appears that each brand of these oils is manufactured slightly different. As such it's hard to know just how they will interact with each other in all situations; however, I've yet to find any problems with the different brands that I've mixed together, either with each of the water miscibles themselves, or with any regular oils. Generally speaking, I'd only use a combination with regular oils if I didn't have that color as a WMO.

Holbein had a document that mentioned keeping the amount of regular oils below @30% of the mix to retain its solubility with water.

Thanks Dave,
It's great to have someone on the forum who has a lot of technical knowledge.
Judy

You're welcome, Judy. Sometimes it's less about knowledge or experience than about record-keeping and making notes.

Thank you Dave! You're knowledge is such a great addition to this forum and greatly appreciated. I was wondering the ratio with the Holbein I did remember reading it somewhere but couldn't find it. I have some W&N conventional oils that I would like to test out with the Holbein.

The only problem I've come across is using WM mediums when adding regular oils to the mix. The paints felt a little gummy. I had a good assortment of regular oils when I started using the WM oils. They went to waste until I started using walnut oil and alkyd, since it mixes well with either and they still clean up with water.
I would be curious about mixing Holbein Duo Aqua with other oils, since the Duos are made to dry fast (touch-dry in 24 hours). I've only used Artisans with other W&N oils (and a few Sennelier and Grumbacher colors).

Callie

The bulk of my WMO paints are DUOs, and I haven't noticed any particular problem with mixing them with other brands, or with regular oils either. I don't think I'd describe DUOs as particularly fast drying, and not usually within 24 hours - depends on how the paint is applied. Alkyds dry faster.

Normally I avoid using water and very little medium if any. If I need to, I make sure and stir them up well on the palette beforehand.