Washes with thinned acrylic paint worked well in the past, but there were some problems. There’d usually be a couple of spots where surface tension caused a ridge of dark. Experimentation didn’t quite lead to the proper look.
I’ve decided to try artist oil washes. They look good in the magazines. If I understand correctly, you can put artist oil washes right over acrylic paint. Will this do any harm to the acrylic finishes? I bought some Winton Oil Colour Burnt Umber and Black and some Mona Lisa Odorless Paint Thinner (odorless mineral spirits). I’m reluctant to try this out without getting some reassurance. The subject is Dragon’s M274 Mechanical Mule.
My personal experience says you need a nice layer of gloss coat before putting washes over acrylic paint. Oil paints themselves do not harm acrylics; however, thinner may, depending on thinner, of course.
Any thinner will probably harm acrylic finish and will go through paint IF you’ll start rubbing it intensively, or will rub for a long time. Definitely do not add more and more thinner to the painted surface - the longer and more thinner there is, the more chances it will harm acrylics.
I can advise to start on some scrap part and train. In my first attempts, I’ve rubbed right through the finish and paint to the plastic. However, after 2-3 attempts I was able to work without harming paints.
And remember - if the thing you rub with starts to get not just a color of oil paint, but the color of acrylics underneath, that means that you’ve eaten through the finish and you need to stop right now, no matter what, or you’ll rub through paint in a couple of rubs. It’s not easily seen in the painted surface; you need to look at your q-tip or whatever you rub with.
Artist’s oils, thinned with odorless mineral spirits or turpenoid should not affect fully cured acrylic model paints, provided you don’t soak the model in thinner for hours. There is one other caveat: you must have good paint adhesion. Grahor, I suspect that is part of the problem you encountered when you rubbed off the acrylic. When removing excess oil wash, use a cloth, swab, or paper towel that is quite wet with thinner. If nothing else, it will help the excess flow into the creveces where you want it.
Make sure you are using pure mineral spirits or turpenoid! Do not use anything containing naptha, lacquer thinner, or alcohol. Those will have very unfortunate effects on your finish.
Whether you apply the wash over a gloss or over a flat depends on the effect you want. When applied over a flat, it’s a good weathering technique. When applied over gloss, a panel-line accent.
With acrylic washes, the addition of a drop of detergent will eliminate the surface tension problem.
I wasn’t using odorless mineral spirits, since there are simply no such thing around here. White spirits, closest equivalent, eats through acrylics. I was using different thinners from different sources, including all our local art shop have, and they all eat through acrylics, some faster, some slower. The thing that sells here as “turpenoid” eats through acrylics faster than you say “that shouldn’t happen!” I’m using now something called “pinen” from art shop, that looks and smells like turpenoid and eats through acrylic very-very slowly.
I forgot you were in the UK, where solvent names are…odd, even odder than over here…
IIRC, “white spirits” are or contain naptha. I’m afraid I can’t advise you as to what “names” contain mineral spirits, and only mineral spirits, over there. Hopefully, someone else from that side of the pond, knowledgeable in your terminology, will chime in.
Thanks for the info guys. I don’t think the thinner I bought has any naptha or alcohol. The label lists odorless mineral spirits as its only ingredient. The paint will have had 2 days to cure once I get back from my little weekend trip. I’ll do some experimenting with the underside of the “Combat ATV” before I do anything with the upper surface. If there’s any problem with the underside I’ll just touch up paint whatever I destroy, future coat the model, then try again. The underside is going to get a dusty pastel chalk attack eventually.
I use a very small amount of linseed oil to thin oil paints. I’ve used enamel thinner to thin them out. I never had any problems using them over acrylics.
Lineseed oil is kinda thick for using it to thinn oils for washes. Like as said, get the odourless thinner. It’s found right by the artist oil paints in the art section. You can add some linedsees oil to enhance the flow and slow the drying or add Japan dryer to have the wash dry in an hour. You only need a drop of each to do the job. I would say not more than 5% of either to the wash. I don’t gloss typically, I will apply a wash over a semi-gloss. It just helps with the final appearance of the weathering. Give it a try and see the results for yourself.
However, after 2-3 attempts I was able to work without harming paints.