I am taking the plunge into air brushing for the first time. And I have two questions. First, once the cake has been painted, can it be placed in the refrigerator? Second, about how long does it take the paint to dry? I understand that humidity has a huge factor, I am just looking for an estimation on the time. I will be covering my cake with MMF.
Thank you so much for any advice you have.

I have airbrushed on fondant cakes a few times. I have yet to refridgerate them afterwards so I don't know that one. I know that the cakes I did took a while to dry. I used a lot of color though and it got kind of gummy until it dried, so be careful not to touch it or it will smear and show up on the cake.

My advice: Turn on the ceiling fan and it will dry faster. I NEVER put my fondant covered cakes in fridge. They sweat when the are brought out and you run the risk of colors running. I find that a ceiling fan does all it needs to to keep the cake cooled, even in hot weather. Hope this helps

If you add vodka and/or lemon extract to the mix you intend to spray, it helps it dry faster.

Also, MMF isn't quite as heavy duty as say, the Wilton brand, so you might want to do a test swatch first before going for it on your cake.

If it seems like the color makes your fondant wilt or it doesn't take the color well, you may want to try thin layers of color and give it time in between to dry a little before adding second or third coats. Just an idea to try.

I usually keep my cakes by a fan too and they dry PDQ.

as long as your mmf is not the shiny greasy kind it should be ok to airbrush. if it has that greasy finish then consider it water proof to the colours and they will likely bead up. also if you chill it after AB then it will sweat while coming to room temp and again the colours will bead up, thats the same for buttercream or fondant. After AB do not touch it as it will smear.

Well, I don't mean to make it confusing...but I have refrigerated my airbrushed cakes most of the time. I never had a beading problem. I agree with the other post reply about spraying thin layers and allowing drying time in between cuz otherwise will cause beading if you're spraying for a darker color..not to mention it will be forever before it dries as well. However, I haven't placed a cake under a ceiling fan and I imagine that's a good tip. Also I use the MMF on the cakes I've placed in my refrigerator. Not sure how I would have responded about the other types of fondant since I haven't used any other.

I too have refrigerated my airbrushed cakes and they have been fine. Do several light coats if you are going for a dark color, to heavy it will run. Ceiling fan works great for drying the paint. Each layer will be dry for the next in about 15 to 20 minutes in my experience. Good luck and have fun, it is a learning experience. And oh yeah, if your MMF is greasy it will not take the paint, like the other CCer said...it will just bead off.

Thank you everyone for all the great tips and advice.

the one time i refridgerated a bc iced cake that was totally airbrushed on coming to room temp, even though it was in a box the cake sweated and the ab colour looked like little pixels, beaded up. it never really did smooth out again, so now i avoid doing it at all.