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Fat Over Lean

I'm on my first oil painting (started before I saw Mark's videos), making a copy of David's Patroclus, which is being done in the French academic style, which is done in four stages, drawing, dead color, first painting, and second painting. I'm in the dead-color stage, where the paint is made lean by mixing with mineral spirits. I'm mostly done with this stage, and was using Old Holland paints. Now I have received my Geneva colors, and want to paint with them, and have a few questions.
1. Is there any problem with applying slower-drying paint over dried, quick-drying paint?
2. I used Gamsol to make my paint lean in this dead-color stage, and have a few areas left to paint in this stage,  so I'm wondering if I can mix Gamsol with my Geneva colors to make them leaner, for the same effect, even though the Geneva paints have extra oil already mixed-in.
3. I assume that just using the Geneva paints straight would give me the fat-over-lean effect in the first painting stage. Is that correct?
4. In the second-painting stage, the next layer, and the final one, should I add a couple of drops of linseed oil to make the Geneva paints even fatter?
5. Since I am painting in layers, where fast-drying paint might be preferable, should I not even worry about questions 1 through 4, but just use the Old Holland paints, and reserve the Geneva colors for my next painting?
6. In considering questions 1 through 5, although I have already been using the "French Academic method," can I simply abandon it with this painting, and switch over to painting Alla Prima on top of it with my Geneva colors?
7. Doing the Patroclus painting is an exercise from a Canadian atelier, where the master painter there likes to add the extreme highlights first. Not only have I added those highlights, but was encouraged by another instructor to put this extreme white over most of the Patroclus figure!! So now I have all of this annoying, extreme white where it shouldn't even be; and after seeing Mark's methods, I much prefer moving from dark to light, and putting in the highlights at the very end of the process. But what to do with this extreme white?? Should I just forget about it, and use Mark's method, and start with the darkest darks, and just develop the painting as if the white wasn't there, painting over it, assuming everything will turn out OK? Or should I try to sand the white off or something before doing that?             


  • Forgot to mention that the painting is being done on a fine linen canvas.
  • my experience in these matters is extremely limited but I would finish the first stage with the same paint/mediums you started with and then decide on switching to Geneva but yes you can go ala prima or you can go in two layers adding a little linseed oil to second layer but you must give the first layer of Geneva adequate time to dry to the touch probably 3-4 weeks - longer if you paint thickly.
  • Forgot #7. I would continue the method you started with and not try to switch to Mark's "Dark to Light" method. But you should follow Mark's method faithfully on your next painting so you can see the difference then choose a method that suits you. Geneva paints work best for ala prima but they can be used for other methods.
  • I am confused about fat over lean. In the past I used the The Artists Handbook medium: 
    3 parts volume of stand oil
    2 parts volume of Damar Varnish
    3 parts volume of turpentine
    1 or 2 drops cobalt drier per pont
    I would paint a thin layer first then
    a thicker layer with less medium
    Is this the correct way to layer oil paint?
    Is this fat over lean?
  • Your "fat" comes from the medium so your first layers should be followed by paint with MORE medium in subsequent layers. You can also put a little oil on a brush and "paint" over a dry layer before adding your next layer of paint.
  • @JohnDevine ; You are asking good questions.

    An issue that bothers me about the Artists Handbook medium is the use of varnish.  If you want your paintings to be restored properly in the future, the use of varnish in the medium prevents conservators from doing so.  The varnish is so integrated with the paint that it cannot be removed or separated from the paint for cleaning.  Varnish should be put on in layers for easy removal at a later time.  Mark's medium recipe is the best that I have come across for archival quality.

    The reason for the fat over lean rule is that we don't want thin layers drying on top before the under layers have either dried first or have a opportunity to do so.  We don't want to encapsulate a layer of paint while it is still drying.  If we do, by putting a thin layer on top, and the top layer dries first, the layer underneath will cause cracking and other problems as it attempts to dry.


  • edited October 2018
    This is interesting as there seems to be different interpretations about the meaning of fat over lean in this thread (and doubtless in many other places  :)
    I was under the same impression that its the way @JohnDevine states.
    I like to do several thin layers and I thin the paint with a small mix of walnut oil and gamsol, adding less of that with each layer. Until the final layer/s are mostly or all just unadulterated paint.

    I can see on the one hand that adding the oil makes it fatter. But I have interpreted it as the thin layer having medium (and is therefore lean) and the fat either non or virtually non and being mostly paint (making it fat) ?
  • If the layer beneath is fully dried/polymerized, then fat over lean doesn’t matter.  Not touch dry, not one month in a warm room, fully dried.

    if the layer beneath is as wet as the layer above, then fat over lean doesn’t matter, because it’s all one layer.

    It’s all about putting slower drying layers over quicker drying, or more dry layers, so that the drying and shrinking all combines perfectly so it doesn’t crack.  This is impossible to achieve perfectly, and is a guideline so that we are doing roughly the right thing, and therefore minimize cracking.

    if you are adding less medium with each layer, you are painting lean over fat, and as all that dries, the differential drying rates should cause cracking and delamination.
  • This is extremely well said and I agree.  There should be no confusion about fat over lean after reading your post.  :)
  • Thanks for clearing that up @PaulB.
    Its looking like I had the wrong thinking on that one.
  • @PaulB
    Im confused again on rereading because of this bit
    "It’s all about putting slower drying layers over quicker drying, or more dry layers"
    As this suggests to me now that I have been doing it correctly.
    My Red tulips that I posted for example, I did initial (thin) layers (5) of the leaves and flowers and those layers dried fairly quickly compared with the thicker final layer.
    Am I enterpreting things wrong ?
  • MichaelD said:
    Am I enterpreting things wrong ?

    Every layer should have more fat.  The topmost layer should have the most fat, and dry the slowest.  Medium = oil = fat.

    if we were able to do this right, and we can’t, a layer would dry before the layer above it dries.
  • @MichaelD how about this for an analogy.

    Bread in the oven bakes from the outside in.  A baguette’s crust hardens first, and then as the inner dough bakes it expands and causes that wonderful rip in the crust.

    It could be a better analogy, but that’s sort of what cracking paint is.
  • Thanks @PaulB ;
    I think I've got it now, so I'm going to start using bread dough as a medium
  • It's like when you grill hamburgers. First the burger then the beer Bacon.
  • Well then it's the French fries over the sauerkraut.
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