First, I wish to thank MITRA for the useful answers to all sorts of painting questions. My question here is about clove oil usage in oil paint. I have read the previous discussions, and hoped for clarification or updates on what the conservationists or paint chemists think.
What percentage of clove oil added to paint will cause future solubility problems when cleaning or removing varnish? The Mark Carder paint and medium users have been told that some clove oil will not harm the paint; and that Mr. Carder had verified this with an unnamed expert.
I do not use clove oil at all, but then neither am I a purist in the sense that anything which has been shown to cause problems – frequently in undefined situations – should not be used.
Clove oil: will 1/10 of`% by volume hurt the paint? Etc.
With what solvents used in future varnish removals will the clove oil cause the most problems?
Can you give any citations to further explore?
Thank you.
Most of the discussion about increased solubility is anecdotal. Conservators who have had to clean paintings known to contain clove oil report an increased sensitivity to solvents. Additionally, I have corresponded with artists who used to, but no longer, used clove oil in their paint and they reported that these works never dried as solidly as those they executed without that additive. I have no exact proportion when this become problematic.
This is not scientific at all, I know. It would be cool to do such a study with know proportions and aging using a range of solvents in a wipe test. Perhaps I can talk a student into this, but it does have drawbacks. The paintings would have to age, and likely long after said students graduated. Artificial aging has its own problem in terms of how closely it the sample actually resembles naturally-aged materials. Additionally for the best results of artificial ageing, the sample needs to be subjected to alternating light and dark aging as well as humidity cycling. I do not have ready access to such an instrument, at least not for as long as such a test would require.
As to which solvents are more likely to disturb the clove oil-containing paint. These are the same as newer oil paint in general. Sensitivity increases with newness and is exacerbated by how polar the solvent mixture is. Odorless mineral spirits at the bottom and acetone way up on the list. Know, though that depending on overall technique and age, I have seen paintings that are readily soluble in mineral spirits and even water.
Of course, you may use clove oil if you wish. If so, please record its use and in what relative proportion somewhere on the painting to aid any future treatment if one is necessary.