Matte clear over Future.

This is like what happens when you wax a repainted car with out waiting for the quemicals in the paint to air out. I just had my Tundra repainted and the painter advised a 3 month wait before waxing. 

I usually wait several days to let the enamel cure before using any clear acrylic over it.

JohnnyK

...I would let the paint cure for a week before applying the Future...

Definitely, though it depends on the type of paint-acrylic, enamel, lacquer, and so on.

One more suggestion. I would let the paint cure for a week before applying the Future. I applied Future over paint that had cured for two days and the Future micro-cracked after about a week. The model was finished at that time and I couldn't remove the Future.

Same here.  I let the Future cure for a couple of days, then I shoot Testor's DullCote over it as the sealer/finish coat, no problem.

I agree with PJ and Bruce. Wait long enough and you can do about anything you want over the top of Future or another acrylic clear coat.

That said, what I ususally do is use Alclad clear. Not the water-based stuff, the real deal Alclad II Klear Kote. It comes in 4 levels of shine: Gloss, Light Sheen, Semi-Matte, Matte, and Flat.

My reasons I usually do this, despite agreeing with PJ and Bruce are a) I feel I don't have to worry if the Future (or some other underlying water-based clear) is fully cured, b) I feel the solvent-based clear is more durable (my opinion, I can't verify that), and most importantly c) the Alclad ALC-314 Flat is the flattest and prettiest flat finish I've seen.

Here is a link to the Alclad site. Caution, Alcad clears can be confusing. The stuff called "Klear Kote" is solvent-based, the "Aqua Gloss Clear" is water based and only available in gloss.

One more thing, if you are still hanging in there on this too-long reply; I pretty much ruined my second model back into the hobby years back with that foggy (Milky) effect you mention. I can't remember what product I sprayed, but I think it was a flat acrylic and most likely Vallejo Flat varnish. It was  after that I bought the Alclad and I've been tickled pink with my flat finishes since.

Oh, and whatever you choose for your flat coat, remember, light, dry coats. Heavy wet coats can cause that "foggy" (miky) effect with Mattes/Flats.

Sorry, that got way to long.

plasticjunkie

You can spray anything over Future as long as it has time to cure. I usually let it sit and cure for a minimum of 2-3 days. I spray Testors flat lacquer all the time over Future without any problems and have been doing this for many years.

 

Same here

You can spray anything over Future as long as it has time to cure. I usually let it sit and cure for a minimum of 2-3 days. I spray Testors flat lacquer all the time over Future without any problems and have been doing this for many years.