fat over lean

[Dudley D]

:confused:
I had the impression (from the readings here) that fat over lean meant thick over thin. I was told last night (in art class) that liquin is considered a fat, and using too much liquin in the first layers of a painting violated the principle of fat over lean. Is liquin a fat? And if so should it be used very sparingly at first with more in the later layers to prevent cracking?
I am thinning my paint a lot with liquin in the first layers. Mostly liquin actually. I was planning on using this thinned mixure in many thin coats until build up is adaquate.

Comments welcome.
Thanks in advance

[Wayne Gaudon]

I don't use it but here is what the dealer's have to say .. Check on the page for fat over lean.
http://www.currys.com/knowledge/oilstech.asp

[Rabbit Twilight]

I too have been confused about this for years, but finally after reading I think I have the concept now. It sounds like your method would be okay as long as you don't come back in for the last stages and use paint straight from the tube.

The thing that I read the other day, was that mediums are fat, (this doesn't include turp), and that as the painting progresses....more and more medium should be added to the paint.

Where I was confused was with glazes. In my mind, I always thought of them as lean, but they are really sound practice because of the amount of medium in the mixture.

Good luck!

[martha gamblin]

Hello.

Fat over lean means apply oil rich layers over lean layers. If you paint lean colors over fat colors, the fat colors will crack the lean colors in order to dry.

Look at the paints to know which are lean and which are fat. The shiny colors are fat. The more matte colors are lean. Mineral colors are more lean. All whites are lean. Modern organic colors are mostly fat.

All painting mediums are fat. By the time you are glazing, you are working on the top layers. The fat over lean rule is really important in the under layers.

When using alkyd resin painting mediums like Liquid or Galkyd as a general painting medium to thin colors and speed drying time, add up to 50% odorless mineral spirits to the under layers. Add more painting medium and less solvent as you move up through the layers.

Best, Martha
martha@gamblincolors.com

[Rabbit Twilight]

Look at the paints to know which are lean and which are fat. The shiny colors are fat. The more matte colors are lean. Mineral colors are more lean. All whites are lean. Modern organic colors are mostly fat.

How does this work if one wants to punch up light areas toward the end of a painting? Does this mean that whites over the previous layers in the final stages of painting will crack over time?

I must say that I love the Gamblin paints and mediums. I ordered some of the colors and a sample set of the mediums. So far, I'm enjoying the Galkyd medium the best. The paints are a real joy to use. Thanks for the hard work that it must take to insure a superiour product.

[WFMartin]

Dudley D,

The real significance of the "fat over lean" concept, as I understand it, lies mainly in the drying speeds of various mediums.

The cracking of upper layers is caused when fast drying mixtures are painted over slower drying mixtures. Read the manufacturers' comments that are in the link that Wayne posted. They claim Liquin (and other alkyd mediums) are fast drying.

Well, that being the case, it would seem to me to be a good idea not to paint with a Liquin rich medium over, let's say a linseed oil or stand oil painted layer. Liquin dries much faster than linseed oil. Whether or not it is considered by those who favor Liquin to be fat is a moot point. It dries faster than linseed of stand oil, and therefore probably should not be painted over an oil laden layer.

Now, what some artists don't realize is that it seems to be just fine to paint lean over lean or fat over fat. That means that it would be fine to use either an oil rich medium for all the layers, or a Liquin rich medium for all the layers.

That's my opinion, as an answer to your question.

Myself? I stick to the tried and true linseed oil and stand oil mediums, however I have used Liquin for a grisaille underpainting, with oil rich mediums over it, and it worked fine.

Bill :)

[martha gamblin]

Hello again. The fat over lean rule is most important in the early stages of the painting. Once you are on the top few layers, you can add highlights or scumbles on top of glaze layers.
Do not wait too long before adding scumbles though so the top layers are still open. If you wait a few weeks to a month, add a clear layer of your painting medium on to area to give your scumbles better adhesion. Best, Martha
martha@gamblincolors.com

[Einion]

One should strive to paint fat over lean and thick over thin as much as possible, but the two terms are not the same since of course a thick layer of paint isn't automatically fat.

Liquin should be considered and used as a fat, so in the lower layers you should use it sparingly if at all. If, for the sake of argument, you painted in six layers the first two shouldn't really have any added medium, just be thinned with turpentine or a substitute.

Einion

[dafonso]

Hi Einion

If I don't want to use turpentine for health reasons, what would be the best substitute you know? I am concerned about harzadous vapors, not even smell.

Thank you alot!! :)

[dafonso]

Hi Einion

Another question! :)

What do you think about the quality of Lefranc & Bourgeois Artist's Fine Oil Color sold at Dickblick??
Workability? Pigmentation?

They were pretty cheao, only $3.59 a tube.

Thank you!!