Thanks for the reply weskerfan,
I want to repaint some figures hair and eyebrows colour, and in many cases beard too, indeed. There are not many pale yellow (wheat or champaign colour) blond or intense orange to red redhaired figures out there -I can think of Prince Harry or actor Ewan McGregor as redhaired examples and Dragon figure Sepp Kiefer as a blond one-. Most figures have dark brown hair today. Even in the case of the Hot Toys Obi Wan head hair is too dark and brownish if you look at actual pics of Ewan McGregor.
I just want a little more diversity in my kitbashes. I have bought too several African bodies and head sculpts of French footballer/soccer player Paul Pogba (Kodoxo brand) and NBA Afroamerican players. I am buying too some of the Chinese DAM heads for Asian American servicemen kitbashes.
It is funny too that most figures today are heavily bearded, Seems like not only special forces soldiers but even regular armies units grunts never shaved at all. (And PMCs in the Green Zone or Bashra or Kabul or elsewhere had easy access to a daily shave). There are even pics of Delta, Seals and SAS and SBS and Spetsnaz operators perfectly shaved out there in the wild. Fortunately DAM KSK and French special forces figures are beardless. Not that I have anything against beard but all figures head sculpts look too much alike.
The issue when painting hair and beard and specially eyebrows is that my hands are not very steady, and I want to use oils rather than acrylic paints for oil paint is very easy to wipe out of the skin of the face, forehead, lips, eyes, etc. with a clean fine brush, when I am not very accurate with the brush and exceeds with the paint the line that separates hair and skin. I have tried acrylics on some old spare heads and they sticks to the surface very hard, so it is very difficult to wipe out the excess of paint. Understable for it is a paint made to dry very fast.
I have been advised at my fine arts store that oil painting uses turpentine as thinner and it can melt plastic or affect badly the paint of the heads, so they have told me I should use a clear varnish to protect the head sculpts before repainting them.
Now the problem here is what varnish I must use -for acrylics maybe?- according to the kind of paint DAM, Soldier Story, E&S, etc use for the heads. I have been told too that some brands varnish (namely Vallejo) gets opaque or clear yellowish after some time.
So any info about what varnish I can use will be wellcome.