A while back right here on Armorama a user mentioned he had issues with a wash (or filter? Can't seem to find the thread unfortunately) making the plastic of his kit brittle, and I've have had a similar issue in the past. When building a snap-fit kit and applying an enamel wash thinned with Home Depot Crown paint thinner, the plastic, especially around the snap-fitted areas were highly susceptible to stress fracturing/cracking. I assume that in my case the paint thinner was a bit too potent for the plastic, causing it to degrade.

Thankfully, I've not had this issue since, but what is the actual cause of this happening? Could it be that some types of plastics are more prone to being damaged/degraded than others? Also, what thinners have you found the safest to use for washes and filters? Thanks much.

Its just that some of the enamel or mineral spirits thinners are "Hot" and can attack plastic.It usually happens on smaller parts like the mounting points for roadwheels.I find if I use them spareingly instead of slopping them on,they work better

was this it?

I think I need a chemistry lesson here. I experienced strange cracks in the tires on the MiniArt BA-64B kit, one even crumbled into several pieces. The tires are the same styrene as the rest of the kit. I masked their inside surface, primed them with AK primer, and painted them in Vallejo acrylic. I then assembled them to similarly prepared wheels with Tamiya extra thin. once assembled to the painted vehicle the whole kit got a coat of Future and several Mig washes. Then a coat of Dullcoat (spray Can). Everything was fine until two coats of Mig filters. Large cracks appeared in 3 of the 4 tires and one had several cracks and crumbled. The tires fit snugly on the wheels, but were not under tension. I was able to salvage then with CA and liberal use of pigments. Any ideas out there? I have used a similar sequence of products many times without incident.

it could have been my topic:

https://armorama.kitmaker.net/forums/218279#1834233

happened to me once more afterwards, again with a Tamiya kit.

Thanks for the tip Anthony. I do go light on the mineral spirits/turpentine when it comes to washes nowadays. I haven't done a filter in a while though in fear of possibly weakening the plastic, as a larger amount of thinner is needed to spread the paint around. I want to experiment with filters more, but it seems like some kits' plastics are more prone to weakening than others, and that's the part I've become weary about.

BGC, thanks for trying to look it up. I don't think that was it, but it looks like you had nearly the same experience. mat, I think your topic was it, actually. I remember watching the topic for replies but lost it when it got pushed down the thread list. In any case, you both seem to have had very similar issues. What do you guys think it was? Have you tried anything different since or have had any new issues with other projects?

I personally think the white spirit attacks the softners in the plastic, it dissolves them. Since my issues occured with Tamiya only, I think their plastic is more vulnerable. I now use less wash on my models, and make sure they dry quicker (I use the AB without paint for that)

Yeah, that does seem to be the case huh I'd best go light with the white spirits on the Tamiya IS-2 I'm working on.

Mig's Abt 502 oils , I made a wash out of the brown and some Grumbacher odorless thinner , when applied to dragons 6060 kit tracks after painting the tracks started to break apart so easily . Maybe the odorless thinner ?