Question about fat over lean (solventless painting)

[dwilliams]

Hello everybody.

I've probably confused myself by overthinking it, but when I'm making a painting with glazes, without using any solvent to thin my medium, how do I obey the fat over lean rule? (I'm using walnut alkyd medium, in case that's important) Normally I would paint the first layer down with half solvent/medium, then thin it down with less solvent in the next layer, and then use just medium in my final layer. I was wondering if I was painting without using any solvent, would I use no medium in the first layer (or just a little) and then more with each subsequent layer? Or do I paint with medium in the beginning layers, and none in the final layers?

Any help would be appreciated.

[bjoern3000]

It depends on your medium.

If the paint is made up of linseed oil then you can use linseed oil when ever you want - in the first layers and in subsequent layers. The fat stays the same.

If the paint is made up of linseed oil and you use a fatter (slower drying) oil as a medium then you should use the medium only in the subsequent layers.

You mentioned your medium - walnut alkyd medium - which is fast drying I think due to the alkyd in it. So you should paint initially with this medium and less in the subsequent layers.

Some info I found quickly via google:
http://painting.about.com/cs/oils/a/dryingoils.htm

[Elwell]

Things get tricky when you introduce alkyds. The idea of fat over lean is that, to avoid cracking, you never want a less flexible layer over a more flexible layer. The walnut alkyd is a very fat medium (no solvent), but also quick drying. And Alkyds are supposed to retain their flexibility longer and better than straight drying oils.
Basically, if you're not using any solvent, you've removed the biggest problem in terms of fat over lean, where people put washy, underbound layers over full-bodied paint. Use the minimum amount of medium you can to get the working characteristics you need (always the best advice, not matter what you are using), no matter which layer, and don't worry about it overmuch.

[bjoern3000]

Do you know, what I thought when I read this:
Use the minimum amount of medium you can to get the working characteristics you need

I thought this:
always the best advice!

:)

[dwilliams]

Thanks for the good advice everybody :)