Sealing prior to wash/filter coat. Attack of the thinner! Advice appreciated...

Just apply Future or Tamiya Clear before oil washes. Once cured, they are impervious to mineral spirits.

That Golden MSA varnish is designed to be the final finish; it's not intended to be painted over. It is also designed to be removed with mineral spirits even after curing is complete. So I think you are using the wrong product to apply a mineral spirit wash to, even if you let it fully cure.

To answer your question, I too have had no trouble with a mineral spirit wash over water-based acrylic varnishes such as MM Acryl and Tamiya. These acrylic paints do not dissolve with mineral spirits once cured, unlike the Golden varnish.

I do think you are on the right track in wanting to thin your oils with spirits rather than oil. Oil has its uses (I use poppy oil sometimes), but thinning isn't one of them.

I also recommend testing on scrap before applying to a piece I really care about.

Chris

Indeed curing/patience is key. I need to work on the latter...

Yeah, I wish I hadn't used linseed oil. Granted I used the 'drying' variety, but I think I'm in for the long haul. I'm planning to port the dry/warm output from a dehumidifier directly onto my model via a dryer hose, in hopes of speeding the process up a bit.

I have never had a problem of mineral spirits (regular, Mona Lisa) eating acrylics. You need to let the acrylic cure, not just dry.

Don't use linseed oil on models.  It takes weeks (or even months) for it to cure.

Hi Nathan,

Thank you for your reply. I've done that in the past and the acrylic didn't hold up to the solvent. Now that I think about it though, I'm wiling to bet I was being impatient and didn't give the acrylic enough time to dry and really harden up.

I will use an acrylic next time and ensure it is fully dry. Thanks again.

You need to seal it with a non oil based clear coat, such as windsor and Newton Acrylic Varnish, Vallejo, Tamiya...any of those acrylic brands.