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  • All about sinking in and oiling outApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2017-08-03 15:19:27 ... Most recent comment 2017-09-04 17:19:32
    Oil Paint Drying Oils Paint Mediums
    Question

    Dear MITRA,

    I encounter a lot of sinking-in due to the large fields of dark colors I use. I’ve been oiling out with straight walnut oil as a final layer in some cases despite the warnings for several reasons: 1) The brushwork is sucessful and seems a shame to repaint. 2) I don't have six months to wait for varnishing. 3) Even when I do oil out, then reapint, I often get more sinking it. 4) It solves the problem in the short term.

    I have read all of the posts relating to this topic (which have given me some good advise about other ways to mitigate the probelm) but still have several quesitons–

    If oil is rubbed into an acrylic ground to deter sinking-in, how does this affect the “fat over lean rule”? If a canvas is prepared this way, can one still paint with a medium that has solvent in it?

    If a layer of paint is oiled out with straight oil, does this mean one shouldn’t use any solvent in their next painted layer?

    I prefer to use straight walnut oil for oiling-out because it is thin and adding solvent can lift the paint, but I have read on this forum that more bodied oils thinned with solvent are better for oiling out. Why is a bodied oil thinned with solvent superior to a thinner straight oil?

    Can a black area of a painting be oiled out as a final layer? Is the inability for a conservator to remove this layer later on the only issue, since I assume true black won’t develop a yellow cast?

    How long does the yellowing process take to appear if a painting has been oiled out as a final layer?

    If cold wax is used in a medium to create a more even color field (i.e. less variation in shine), can the painting still be oiled out?

    Thank you so much.

Answers and Comments
  • EditDeleteModerator Answer

    ​If paint is lifting when oiling out, the initial layer is probably not dry enough yet. You may want to try a different medium, maybe alkyd-based. For a very long time, artists have employed mediums that render paint faster drying and, when touch-dry, less vulnerable to staining and re-wetting. The de Mayerne manuscript describes (vaguely) the "Amber Oil of Venice" that was used in the Gentileschi studio for flesh and white passages, to facilitate prompt overpainting and reduce staining of light colors. There are lots of factory-prepared mediums that deliver these benefits today. A medium that imparts gloss will also reduce sinking of colors.

    If the paint film contains significant amounts of wax, I would not advise oiling out or any heavy manipulation. Wax tends to dull a paint layer so if you are having difficulty achieving deep darks, wax may not be the best choice.

    Matthew Kinsey, Utrecht Art Supplies
    2017-08-03 21:07:26
  • EditDeleteModerator Answer

    Some of these are well answered in our resources section about oiling out. I am sensing that you are restating these questions because you do not really like the answers we have provided ;) I will briefly address each of your questions.

    The fat over lean “rule” is an over simplification. The important notion is more rigid and brittle under less rigid and more flexible. In this instance, this is not the important factor. If you rub walnut oil into the acrylic dispersion ground and paint into it before it has dried, the oil becomes incorporated into the paint and is not a discrete layer any more. We really advise to not apply oil as a coating that is allowed to dry before paint is applied. The reasons for this are enumerated in our resource section. A properly dried paint film should be resilient to the application of additional layers of paint containing solvents as long as the solvent choice is not too “hot” or slow evaporating. This is one of my issues with spike oil which evaporate so slowly that is can dissolve paint films that have set for a reasonable amount of time.

    Bodied oils tend to provide a slightly sticky surface after the solvent has evaporated. This may or may not facilitate your intended effects. In addition, stand oil is less yellowing that unprocessed oil. There is nothing wrong with using walnut oil, as long as you are going to paint into that oil and cover it completely with layers of pigmented paint. I sense this is not what you want to hear.

    Unfortunately, it is a bad idea to leave dried oil exposed, even over dark paint layers. It will yellow, but also become turbid over time. These areas will eventually be seen as slightly brownish-green. No, it will not be as visually disturbing as exposed oil on light colors or white, but it will still become visually apparent.

    There are too many factors here to give an exact timeframe for yellowing. Again, I am sensing that you want to hear that if you have not seen this in X amount of time, there is not a problem. I cannot offer that assurance.

    Unless the effect created by additions of wax are essential to your aesthetic aims, I caution against incorporating it INTO oil paint. There is not a real problem with this but if large amounts are added, the work should be treated as something different than a traditional oil painting and certainly information about the media and wax should be noted and retained on or with the painting. You should also seriously deliberate whether to varnish such a work. Wax will remain eternally soluble in mild organic solvents making it difficult to remove a discolored varnish if a substantial amount of wax has been added.

    If you oil out into a couch of wax you are likely going to slightly dissolve the wax into the oil. This would be preferably to having a discrete wax layer between layers of oil paint. Wax interlayers could be “undercut” during varnish removal, which could scale away the uppermost oil layer. This is the worst-case scenario but it is certainly possible with wax interlayers. Again, please record you working materials and layering on the painting if you are going to use this technique.  You could also make a note on your painting that you would prefer that your paint not be cleaned in the future due to your medium or varnish decisions. As always, it is better to provide future conservators with more rather than less information.

    I hope this was of some help.

    Brian Baade
    2017-08-03 22:56:19
  • ApproveRejectUn-ApproveUser Comment

    ​Thank you so much Matthew and Brian! This is all so amazingly helpful. 

    2017-08-03 23:51:36
  • ApproveRejectUn-ApproveUser Comment

    ​Brian, if I'm understanding correctly, you advise here against rubbing oil directly into an acrylic ground to lesson its absorbancy unless one is immediately painting over it and thus incorporating that oil into the paint film itself. But I am wondering, would you *also* advise against rubbing a small amount of Walnut Alkyd Medium into a substrate such as a Claybord panel (to lesson absorbancy) that would be left to touch-dry before continueing on with oil paint? Thanks for your thoughts, Susan

    2017-08-13 13:07:29
  • EditDeleteModerator Answer

    There are a couple of different components here. One of the main concern with oiling out is that any portions that are left exposed WILL yellow over time and become unsightly. We see this frequently on paintings that enter our conservation lab to be cleaned. These regions remain irretrievably darker and yellower than the sections of the surface that received subsequent layers of pigmented paint.

    The nice thing about painting into wet oil is that it becomes incorporated into the paint and is not a discrete fatty layer between more rigid layers of paint. If this layer if substantial, it will violate the general principle of keeping the more rigid layers below the less rigid layers, This would be even more problematic for canvas paintings as generally flex far more than panel paintings.

    However, one can successfully apply a minimal layer of oil/medium to cut the absorbency if one is rigorous about only adding just enough to achieve the desired effect.  I know that some knowledgably commentators state that this dried layer can be left uncovered BUT my experience in conserving paintings leads me to caution against this practice.

    Finally, I do think that your proposal to lessen the absorbency of a Clayboard panel is doable. I have done this to the same product when my project required a less absorbent ground that the untreated product. I will contact Amperstand to get their take on this as they have done a lot of R & D and testing of their products.

    Brian Baade
    2017-08-13 13:42:42
  • ApproveRejectUn-ApproveUser Comment

    Very glad to hear your experience and thoughts on this, Brian. I have that same question in to the Ampersand folks at the moment, and they seem to be very good about getting back with answers. Your conservator's experience on this subject is appreciated. Did you let that oil/ground touch-dry before painting, or proceed immediately with paint? Either way, very good news! ♡

    2017-08-13 14:25:27
  • EditDeleteModerator Answer

    A VERY MINIMAL amount of alkyd medium rubbed on very thin using a pad of lint-free cotton fabric. This was allowed to completely dry before working on it. It was later completely covered with paint.

    Brian Baade
    2017-08-13 14:33:27
  • ApproveRejectUn-ApproveUser Comment

    ​Thanks, Brian!

    2017-08-13 14:50:21
  • ApproveRejectUn-ApproveUser Comment

    ​Hi Susan - I agree with Brian. I would recommend using your preference of walnut alkyd medium or solvent free medium (fluid) wiping in a SMALL amount to reduce the absorbency of the surface. Then, once this has dried thoroughly, you can paint with oil paint on this surface. Be sure (as mentioned) to cover the surface with paint, leaving no oiled areas exposed. - Dana at Ampersand Art Supply

    2017-08-14 12:41:52
  • ApproveRejectUn-ApproveUser Comment

    ​Thanks, Dana from Ampersand. (twice!)

    2017-08-14 15:56:50
  • ApproveRejectUn-ApproveUser Comment

    ​I have also used walnut alkyd to reduce the absorbency of Claybord; Brian is correct in saying that very little is needed. I typically wipe a small, even amount across the surface of the panel. You don't want medium pooling on the surface of the panel, but use enough to get an even sheen. Then I let it sit for about three minutes, and then wipe off as much medium as I can using a dry, lint-free cloth. The idea being to allow the medium to soak into the panel (which it will do, since Claybord is absorbent and alkyd medium is very thin), but then remove as much from the surface as possible. When dry, the surface should be matte, with no sheen at all. It should also still be a little bit absorbent (but not so much that you paint will sink in). 

    The other method that I've found to be effective for sealing Claybord is to give it a light spray of Lascaux Fixativ, which is Paraloid B-72 resin in solvent. Again, light is the key--you don't want a glossy coating that eliminates all absorbency. 

    -Ben

    2017-09-04 17:19:32
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