Ok, so I made marshmallow fondant for the first time. It turned out great. I covered my 2 layer cake with it, as per normal. No issues so far, and it was all smooth, air bubbles all pushed out with my fondant smoother and everything.

I got Duff's designer prints and decided to try them out for the first time. So, I put the border on my fondant, and my fondant is EXPLODING or something!! Air bubbles are GROWING under my fondant, ripping it and messing up the border! I've tried to smooth them out by gliding the smoother downward, pushing the air out, even sealing the bottom, but my entire cake is ruined! The top is smooth, but all the way around it is full of HUGE air bubbles!

Can anyone tell me what caused this? Was it the Marshmallow fondant? I usually use commercial fondant.

Oh wow! I'm am wanting to make the leap to making my own mmf but have to work up the nerve, so this is making me nervous. I'll be interested to see what everyone says. Hope you get it figured out! So sorry, that's got to be frustrating.

http://cakecentral.com/cake-decorating-ftopict-718007-air.html+bubbles+fondant

http://cakecentral.com/cake-decorating-ftopict-716507-air.html+bubbles+fondant

http://cakecentral.com/cake-decorating-ftopict-713033-air.html+bubbles+fondant

http://cakecentral.com/cake-decorating-ftopict-712345-air.html+bubbles+fondant

http://cakecentral.com/cake-decorating-ftopict-686940-air.html+bubbles+fondant

Sounds to me like the cake is settling. As a cake settles, the air inside and between the layers starts to push out the sides. The more you press down on the top to smooth the fondant, the more air that is pushed out of the cake and it has to go somewhere. I usually fill and crumb-coat my cake then put a piece of wax paper over the top and a 12" tile on top of that for at least an hour (I use a 16" tile for cakes over 12" in diameter). I always have to smooth the sides again (from the air pushing out) before adding the fondant.

I'm agreeing with langranny

I've only used mmf since starting. I had trouble with air bubbles (still do if I rush) until I was given advice to let the cake settle before covering in fondant.

If it's a small air bubble and it just wont come out, you can take a needle and stick it in the bubble at a 45° angle, push the air out and the hole will somewhat cover itself up. If you can still see the pinhole, strategically place a decoration over the spot.

HTH

Watch this video. I am going to try this next time. I would have never thought about twisting the fondant while I knead it to help prevent air bubbles. I agree with the other posters. I frost my cakes and place a piece of wax paper and place a plate with a flat bottom on top and let them settle for a couple of hours. This lets the gases escape before you cover with fondant. http://www.youtube.com/watch?v=yfy7jtkQnCA&feature=related

Kind of interesting about twisting, but I have always twisted my fondant and still get air bubbles from time to time. I think the issues described are cake related though, considering the bubbles are under the fondant and can be moved around.
That being said though.... thank you for the video link. Every bit of information helps everyone... even just people reading the forum.

I know this is off the topic but I've noticed that my mmf has started cracking once it's dried and on the cake. Does anyone know why?

Not really sure why Claire... dry climate or warm room? It could even be something like a non brand name marshmallow. But for now, try rubbing it down with a super light coat of crisco and knead it in really well just before covering your cake. It may help the moisture stay in a bit longer.

I guess I could add... when you roll it out on PS or cornstarch it can dry it out even more, so that last little bit of crisco should help it.

Thanks Darthburn, it has gotten warmer here so I'm guessing that's the problem as it's the first time I've come across it.