Strange spotting/fogging on oil painting on aluminum ApproveRejectUn-ApproveSubscribeUn-Unsubscribe
Question asked 2017-06-14 13:40:09 ...
Most recent comment 2017-06-14 23:20:40
I used an aluminum panel for a painting support for an oil painting for the first time. A month after the painting dried to the touch, I wrapped it unvarnished in acid-free tissue, wrapped in foam, then in bubble wrap in a cardboard box on a flight. It was wrapped this way for about 1 week. When I hung it for my exhibition I noticed strange splotches that resemble mold. They are not uniform and were not there before packing. The aluminum was purchased at an art store with plastic vacuum sealed to both sides. I took off the plastic and primed it with 4-6 layers of Grumbacher Gesso for oils, sanding between each layer. I used Rublev Raw French Umber thinned with Rublesol for the underpainting, followed by Rublev paint straight from the tube with no medium added. The main colors I used were Lamp Black and Lead white. Is there some reason you can imagine that would cause this type of reaction? Will it go away when I varnish? I've read that using denatured alcohol and lead primer would help prevent this in the future (whatever this is), but wouldn't so many layers of gesso be good enough? Thank you!
Answers and Comments
I'm wondering if the discoloration was the result of a reaction between the white pigment and something in the packing materials. What sort of "foam" was used to wrap the artwork?
Regarding the preparation of an aluminum panel for acrylic dispersion painting ground, I recall Gottsegen recommended finely graining the support with steel wool followed with a thorough cleaning with denatured alcohol, to ensure optimal adhesion. I don't remember any issue with discoloration from aluminum panel, however.
Is there any way for you to post a picture of the problem?
So to begin we do not think this has anything to do with the aluminum support or the materials/techniques you are using. It is indeed strange looking and still a bit impossible to diagnosis without examining the surface in person so we will do our best to try and give you some advice here...
1) It could be fatty acid effluorescence but I am leaning towards not. The primary reason being that I have never seen FA effluorescence that appears in such distinct circular patterns. To deal with this problem one can use a soft brush and/or a bit of OMS to wipe the stuff away and certainly varnishing will help if that does not fix the problem.
2) This might be some sort of additive from one of the packaging materials that got deposited on the painting (thinking along the lines of PVC or something?). It is harder to advise on how to deal with this as it will entirely depend on the additive. Have you tried taking OMS to the surface? What does it do? Varnishing may or may not help but you also might risk locking in whatever additive you are dealing with....which again may or may not be a big deal.
3) This could be mold....hard to tell. You can look up instructions on how best to deal with mold on paintings in our Resources section (there is a mold abatement document). Even if it is not mold it cannot hurt to treat the surface as if it were affected by a mold outbreak. After that then yes I probably would seal the surface with varnish.
I am sorry we cannot offer a more definitive answer...please let us know if you find out anything.
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