Can sandpaper be used on a fine art oil painting to get rid of too much sheen from poppy seed oil?
Asked by plausable
Not knowing anything about the particular painting in question, I'll have to answer this in general terms. There are some important characteristics of oil painting to understand, and the conclusion will almost certainly be, 'leave it alone' or 'take it to a professional art restorer', that is a 'conservator' – who, if ethical may very well tell you to 'leave it alone', otherwise look for a 'Sympathetic restoration”. Many contemporary paintings do not use a protective coating (varnish) and the sheen could actually be part of the artists original intention.
By far the safest way to control sheen is to light the painting properly. Use an oblique directional light overhead of the painting. Then the observer will not be in line with the reflected light. If your painting is dirty, then it could be cleaned to restore it closer to the original but beware that there is certain expectation for signs of age in an old painting, and full restoration could devalue it.
Any amateur attempt at 'improving' an antique of any kind will result in loss of value – even if it makes it look better. In fact skilled professional repairs can sometimes devalue an antique. So you need to be careful. After a one to two YEAR drying time, new oil-painted pictures should only be varnished with a clear white spirit or essential-oil varnish. To improve elasticity, a small amount of linseed oil should be applied.
If the painting is worth a lot of money, is sentimental or known to be increasing in value, then take it to a recognised restorer. Even if is your own work, and/or you can take some level of risk with it, then I would still not use sandpaper.
For a valueless work, and a bucket full of reckless courage, maybe one of those 'magic sponges' - (they are the ones with a micro-abrasive) will do the trick. It will remove grease and dirt and is usually safe on most surfaces. There are no chemicals involved either. One of the 'side' effects of these sponges is how they can take the sheen off certain kinds of shiny surfaces which you may be able to use to your advantage. But I'd have to state that trying such a technique would be entirely at your own risk, and rather unusual.
It might also depend on the age and how long it has had to cure. It will also depend on the texture of your painting. For sure, any high-spots would get sanded off if you use sandpaper and ruin your painting. After all, to remove high-spots is the purpose of sanding. The magic-sponges are quite delicate and will tear themselves up when used on a rough surface. Either way it sounds risky to me. This might suggest the best way is a chemical preparation of some kind, but again, this is a specialist area as whatever you use needs to be neutralized afterwards, and if the painting was produced by a skilled artist, it might use poppy seed oil as a medium for the pigment. If that is the case, then you won't want to use a chemical agent that dissolves it. Properly cleaning an artwork depends upon knowing exactly what materials are involved.
Surprisingly even water which seems benign is a powerful solvent and using water on an oil painting could seep into small cracks and lift the paint off the sisal. Water will also damage an acrylic painting.
Many artists use layers of paint on layers of paint using a technique known as 'fat over lean' which describes how the under layers are less oily and thin, and the upper layers are more oily and textured.
In general, faster drying mediums are layered under slower drying mediums. Since poppy-seed is slower to dry than linseed-oil, then you expect to find poppy-seed oil over the top of linseed-oil. Poppy-seed should not be used as a ground medium, and Linseed oil should not be used over the top of poppy-seed oil. You might find poppy-seed varnishes used over linseed oil medium because it is clear and won't yellow or darken much. However, it is considered less robust than linseed oil varnishes.
Using the fat-over-lean technique, the oil dries properly and prevents poor adhesion and cracking. If your painting used this technique, then the sheen that you see may well be part of the actual painting and not a protective coating. If that is the case, then attempting to remove the sheen will ruin the painting.
Short answer - Don't use sandpaper on any painting (shock-horror!)– instead try to display it properly using good lighting. If your painting is dirty, gently dust it – that's all. If it is really dirty then engage a specialist.