Hi,
I’ve just painted the base colour on my Warrior AFV and sealed it with TAMIYA Clear X-22 (thinned with TAMIYA thinner in a 60:40 ratio) in preparation for the washes. Is it ok to wash with white-spirit thinned oils over X-22? Will it cause the paint that has already been laid to crack or raise? Any advice would be appreciated.
Cheers
Phil
If the acrilic coat has hardened properly then ginving an oils wash should be no problem.
The rule of thumb is: acrylic paint=oil washes and oil/enamel paint=acrylic washes
That depends on the particular brand of white spirit. As a rule, pure white spirit theoretically does not damage acrylic paint at all, but of all white spirit brands I’ve used, none of them were pure; they do not damage acrylic paint by themselves, but if you start to wipe excessive wash out, you have only limited amount of rubs at one place you can do untill you’ll start to rub off acrylic paint. Very annoying. You have to try it for yourself, on some scrap piece, before starting on a model.
Currently I use two things for oil washes - a mix of white spirit and lineseed oil, which does not damage acrilycs at all; however, it cures forever and then a week more. On a plus side, you can experiment with it as much as you want without fear. On the minus side, after you are satisfied, you’ll have to leave painted piece somewhere where it wouldn’t be disturbed by anyone for at least a week, or else.
Second mix is something which is called “pinen” - as with the first mix, I’ve bought it in the artist’s shop. It cures fast, and allows a lot more rubbing than all the brands of white spirit I was able to locate here. A bit too fast for my tastes, though. 
If you can get what is called “mineral spirits” in pure form, you will be fine. The problem with “white spirits” as they are called, is that they frequently contain either or both naptha and methyl or ethyl alcohol—both of which will attack acrylics intended for use on plastic, particularly.
An alternative you might be able to find is “turpenoid,” a synthetic turpentine substitute. This might also be the “pinen” mentioned by Grahor.
I read a tip once about using Vorasol[sp]?
Again, not all “turpenoid” is the same “turpenoid” - as with other turpentines, it differs by country and by brand.
This is what I’ve found while surfing through online shops: thinner for oil washes.
This turpentine is supposedly “tested” and supposedly perfectly safe for acrylics. I haven’t tested it. May be you can find it in your local hobby shop (it’s produced in Spain) or order it (an order will cost you somewhere between 4 and 8 euro in shipment).
[#ditto] about the variation in content and names of commercial solvents—they vary from country to country. Even here in NA, where US producers and terminology predominate, the problem can really bite you. (Search the forums on “lacquer thinner” and you’ll see what I mean.
If you can find the equivalent of an MSDS from the manufacturer, it could save you a lot of greif. I know the EU has an equivalent, and I think Britain still retains it’s own system.