MITRA Forum Question Details

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Thank you for your time, Brian. It seems that in my efforts to be thorough and give you all the information, I became unclear in describing my issue.

Regarding my practice, fortunately I am already working as you described. I am well acquainted with the fat over lean information that you provided, though I appreciate the reminder that the process is a bit more forgiving than some sources would indicate. I use very little solvent, mechanically thinning my underpainting rather than overusing OMS. Also, rest assured that I haven't oiled out – it is not a part of my practice.

You asked, “First, why wipe an acrylic dispersion underpainting down with Turp or OMS?" and “Second, why are you “wiping"? Unless the painting (acrylic or oil) has been left dormant for some time, I do not understand the reasoning for this." To clarify, I don't underpaint with acrylics -- this is an oil painting with an oil underpainting, but the linen was first primed with an acrylic dispersion primer “gesso". I began the painting several years ago. It had been dormant for quite some time until I resumed work on it this year. It had also been through two studio moves. When I previously used distilled water to clean off a couple of spots last year, it only made a slight difference. OMS worked better, but it took artist's rectified turpentine to clean them off. I noticed a couple more spots recently, so I cleaned them with the turps, which unfortunately apparently brought up more impurities as detailed in my recent earlier post. This is definitely not a part of my usual practice.

To clarify the current issue, by the oil “leaching", perhaps I should have said “seeping." Your description, “Do you mean that there is a sort of crawling ring that radiates from the area?" is a good one. I've never seen anything like it, since the preceding layer was a lean, mechanically thinned underpainting. As this ring emerged, I wiped off the oil edges from my freshly applied passage as they gradually seeped out, because I am familiar with the potential pitfalls of applying straight oil medium -- via such practices such as oiling out or using an oil medium in lieu of a varnish -- thanks to such informational resources as you listed. I was concerned that such an oil ring would result in discoloration were I to leave it showing, or adhesion issues were I to overpaint (as I had been planning to eventually do in this area). In the photographs I provided, while the freshly applied passage in question is fatter, it is still wet, which is why it looks that shiny. I've been working on other similar areas of this work with the identical underpainting, pigment mixtures, and medium ratio for some time with no such issues. The only difference is that I recently cleaned the underpainting in this area as I described above.

You said: “I cannot tell exactly from the images, but PERHAPS there is a transition where the oil from the fat paint saturates the perimeter of the more lean paint, saturating the color." Yes, that is indeed what was happening. Unfortunately, in a few small areas, it does appear to have continued to seep again after I left the studio. These edges do not appear as shiny/fat as the painted passage, however, if that provides any additional clues.

I hope my issue is now clearer. If you are able to advise based on the information I have provided, I would very much appreciate your suggestions for how I should best proceed, both regarding how to keep such seeping from happening again while I work on nearby future passages, as well as what to do with the little oil edges that seeped back out in the initial trouble zone. If you think these edges are not problematic and I can overpaint with a slightly fatter layer as you described, that's great news.

Many thanks again.​

​As a replying uncertain lurker.  Is it just oil medium separating from the surface or oil medium rich paint seeping.  

Is whatever that's seeping, doing so from under another layer, or directly from the top surface?

Marc.​​

Hi Brian and Marc,

Marc -- since it happened as I was painting a second layer on the dry, lean underpainting, it appears to have slowly seeped from the edges of the wet paint a few minutes after I completed the passage. It seemed to be coming from underneath the wet paint if that's what you mean, though I didn't apply my paint very thickly. Any thoughts or ideas are greatly appreciated!

Brian -- this was a very high quality, single-primed Belgian linen (I find single primed to be easier to stretch than raw canvas), and then I applied several coats of an acrylic dispersion primer made by a respected manufacturer -- they do the Just Paint blog and newsletter than you recommended . So I don't think that's the culprit, though I don't know the source of the ground used by the manufacturer of the Belgian linen. However, since it only happened in the area where I cleaned with turps (and that same ill-fated cleaning is what brought up the impurities in the nearby green grass areas that we discussed in the other recent thread), I can only think that there is some connection, though it makes no sense to me. I plan to check with the manufacturers of my paint and the primer to see if they have any ideas -- the only other thing I could think of is a light sanding on the underpainting to increase the tooth, giving the oil medium of future passages a place to better "grip and settle into" -- does that sound reasonable?

My other thought was, regardless of what may have caused it, I now have a few edges of oil that seeped out after I thought I had saved the day by wiping off the initial oil seepage. What is to be done with those edges? Is it safe to overpaint, or should I consider very lightly sanding those existing dry, thin edges as well? (I have sanded before, though it is not a usual part of my practice. I do have a mask suitable for use with pastels that should be an appropriate safety precaution.)

If you think taking different photographs would help (closer details, or from an angle or with raking light, etc.) I'd be happy to provide them, though I certainly understand that it is more difficult to diagnose such a thing from photographs rather than seeing the actual painting.

I do appreciate your time and expertise, and welcome anyone else to weigh in if they have any ideas.

​All the best to you both. 

So fresh oil is separating from under the freshly applied paint?

​Sounds like far too much added medium or poorly made paint to me.  Granted a glossly surface wouldn't help, but it wouldn't solely cause this.

I have seen this fresh dripping/seeping effect only once before, and they were using far too much oil medium. I didn't see them paint it, but they were clearly using too much.  They started with too much, and continued to keep adding layers of ever greater amounts. (yours is a mild case by comparision)  In the end their painting wouldn't even dry.

To begin with, I was wondering if it was a case of apparently dried paint reliquefying, (this has, if rarely, happened before with semi-drying oil bound paint with slow drying pigments sealed off from light and oxygen) but this doesn't seem to what has happened.

Marc.​​

I appreciate your brainstorming, Marc, and I can certainly see why you would suggest too oily of a paint mixture as the cause. However, I am pretty meticulous with my ratios, and actually only use around a third of what the paint manufacturer lists as the maximum amount of alkyd/oil medium. I had also recently been using these exact same admixtures in a similar passage on the same underpainting, just in a different spot. It definitely seems to be a result of having cleaned this area with the turps, because this is the only region of the entire painting that is behaving differently, and that is the only differing factor.​

I applied my paint fairly thinly, so when I said that it appeared to be coming from underneath, it may have only been a trick of the eye due to the slight height difference from the top of the paint passage and the surrounding underpainting, and how the oil was seeping/slightly spreading from the paint.

If you have any other ideas, particularly with what I can do with the edges that seeped back out, I welcome them. 

All the best!