It could even be both. (I told you mold/mould was wierd!)
Either mold or crystalline growth require moisture. Is the cabinet vented, and is the vent near the model?
I assume the artist’s acrylics were diluted before spray application. What did you dilute them with?
I know this isn’t the cause, but there were some models done by Verlinden in the Tamiya HQ display case in Shizuoka City. The crystalline growth (and it was definitely crystals) sometmes reached a length of about a half inch, and was sprouting from the models’ surface. At the time, I thought it must have been baking soda leeching out and somehow growing, as one model that sticks out in my mind was a Merkava with non slip texure added. Also a Greman one where it was coming from a muffler - also given some sort of texture. Good thing you’re getting rid of it now.
Since, as we all know, there’s a specific, specialized tool for just about every job under the sun, here’s one for doing the recessed paint fill job. These look kind of funky, but they actually do work. (I use these fairly often for non-modeling jobs.)
Well, other than those of us who read it as a regex, and therefore as all of mld, mold, moold, mooold, moooold and so on until a number of os only limited by available memory 
Thank you! I just ordered the larger version for testing.
This gaves me an idea - leftover hypodermic needle and syringe. I might have to try it.
Not my build pictured, but demonstrates why your technique, which I also allude to above, works well. I always paint the inside first.
Same build:
Don’t taste it!!! When I was in college, a graduate assistant’s last words were, “Tastes sweet.” Tasting went out as an analytical tool, even among field geologists, in 1971. (Yes, it was still in textbooks then—I have one.)
You could try to dissolve it, which would narrow down the possibilities. Try water on the stuff you scraped off. Scrape off some mor and see if it will dissolve in acid (vinegar will work if you have nothing else.) If you used tap water to dilute the artist’s acrylic, that could be the culprit. If you used tap water to clean the airbrush beforehand, that could also be the culprit. Tap water only has to be potable (safely drinkable). That means it doesn’t contain anything in sufficient quantities to kill you or make you sick.
The perspex cabinet isn’t exactly hermetic, maybe 1 or 2mm gap between front flap & case all round, so there is minor air circulation. The cabinet has been in fairly dry (Australian) indoor conditions for maybe 10 years. As mentioned no other model in the case shows any “snow”.
Yes the artists’ acrylics were diluted with tap-water before application - the dunkelgelb applied with a brush, the green sprayed. (Responding to 18bravo – wow! But no baking soda anywhere near this one)
Yeah I bailed out on the taste test for reasons you mention, it’s just not worth dying or getting seriously ill for one’s Art. As for the quality of the tap water, Sydney’s is virtually free of all limescale, it’s filtered through sandstone & sandy flood-plains. So for example our kettles last for many years.
Maybe I should try to find some litmus paper, its acidity or alkaline-ness might help solve the mystery.
But really, let’s get back to the thread subject, otherwise I’ll have to start a whole new thread on Model Decay.
That would be a very interesting exchange of information and sounds like a good topic.
Well we already covered vinyl-t*re decay in some old threads, I think the more pressing subject is probably about model-makers’ decay…
I quit using Tamiya flat clear because of the frosting. I switched to AK Ultra Matte Varnish.
You could try using the new paint pens that AK and a few other companies have recently released its one of the reasons I put them in the amazon cart,
Yes a final flat varnish (which doesn’t frost) is one solution as long as it doesn’t deteriorate over time – arguably a better solution to what I was using, Tamiya Flat Base which isn’t a varnish but an additive mixed into acrylic paint mixes. I wanted to avoid any final varnish because I didn’t trust what it might do to (ironically) the non-standard acrylics I was using, and/or decals, and/or in quite a few cases I was using my large stocks (late ‘80’s vintage) of Letraset - at least they’re still good without a varnish, no sign of peeling.
If you dilute Tamiya Flat Clear: 1 part Future; 3 parts Tamiya, you’ll get a nice smooth flat finish without frosting. Playing with the dilution ratio will get varying degrees of flat - satin finish.
