Ok so I just spent 3-4 weeks painting/weathering the lower hull of my latest project and applied the flat coat today and it frosted. Been using this same painting and weathering technique for years and never had a problem till today. The base coat is Tamiya over Tamiya primer and sealed with Future. Weathered with oil washes. All steps were allowed to dry thoroughly before moving on to the next application, a minimum of 72hrs more in most cases due to my limited opportunities to model. The flat coat was Polly Scale clear flat thinned with 70% iso like I always ust it but for some reason it frosted very similar to the way the Tamiya clear flat does when used straight. Any ideas on why this happened or how to fix it short of stripping the whole thing and starting over?

Temperature?




cheers

Everytime I used future and then flat coat with either Tamiya flat or Model Master flat, it frosts. I think it is the Future that does it

So what Flat works for you over Future? Also, is that the new Tamiya XF-86 flat? Thanks.

I mistyped that- the Model Master acylic flat works fine. It's the Tamiya Flat base mixed with thinner over Future that fogs on me. I have not tried the XF-84 stuff

Doubt if it was the temp or humidity about 68F and low humidity. As I said I used my "standard proceedure" which I have been using for years without any problems. I used Polly Scale Flat thinned with 70% iso so it might be possible that the alcohol attacked the Future causing the frost, especiall since I don't measure but just eyeball the consistency of the mixture. It's possible that I used more iso than usual-I was careless or distracted while mixing? Any ideas for a salvaging what I have short of stripping and redoing the damn thing over?

Hi,
Tamiya flat base is not made to be used as a flat coat on its own. Its an additive for other tamiya paints. I mix tamiya flat base with Tamiya gloss or in future either one and shoot it over future gloss on every tank i build and never have issues. I dont spray it on very humid or rainy days as it can affect the finish. I have tried Model masters flat and it frost way too easily so i use my tamiya mix for flat coat exclusively. And it holds up to any of my weathering oils and mineral spirits.
Hope that helps.

Gary

There are two possible culprits here - the PollyScale and the alcohol. I've switched to Micro Flat because the last few bottles of PS flat have all tended to frost on me, even though I only thin them with water. (I used to love the stuff, but my guess is they changed the formula in recent years...) Any "flat" will tend to frost up if put on too heavy, supposedly due to a build-up of the talc within it that is visible if the coating is too thick - mainly it fills corners like a milky wash, but it also generally "fogs" the flat surfaces. If this is the problem then the only cure I can think of is a strip & repaint.

Then there is the alcohol, which may be attacking one of your paint layers. In the model train world a quick "dust" technique is to spray on a coat of Model Master Dullcoat and then spritze it with a mist of alcohol to make it go frosty. This effect is more general than the "milky wash" and does not collect in corners. It can be reversed with a fresh coat of Dullcoat, so I think the alcohol only roughs-up the surface texture of the Dullcoat. If this is your cause you could try a water-thinned coat of PS Flat before consigning the hull to paint stripper, just in case it saves the day...

Tom

Try spraying on a coat of future to see if it fixes the frost. Sometimes this works for me.

I have had similar problems with PS flat. One culprit is too much water. Another is too much air. I find it very annoying, but have had to be VERY careful when adding a flat coat.

Interestingly, I brushed on some PS flat recently and it came out semi-gloss after drying. I suspect since the PS line has been discontinued, it may be an age problem with the flats, but that's only speculation.

Thanks to all for the input. Even though I've used PS for years and never had a problem I am leaning toward the idea that maybe they changed the formula. Really liked the stuff though. Happy to report that I experimented on the undersurface of the hull, suspecting that only the surface was effected as Tom suggested. I smply reapplied the oil wash and waited to see it the frost reappeared. It's been almost 24hrs and no sign yet, but the proof will be onlt when the wash is fully dried/cured. Keeping my fingers crossed.