What happened to this cake?

First let me say that I am no fondant expert. I don't cover many cakes. But without knowing first hand how the buttercream set or how delicate the cake was, my only other guess would be an air bubble. The fondant looks a bit dry and so an air bubble may have caused the cracking. But it is really just a guess.

Looking forward to a professional responses to your question.  I did a large cake this weekend.  3 of the tiers did fine but a 12" tier that I used Satin Ice colored with Wilton Cornflower blue did exactly what your cake did.  The fondant was dry and got a large air bubble under it.  I wasn't sure what to do. 

Hi laura475

 

Did you use icing sugar or cornstarch (cornflour) to roll out the fondant? Cornflour CAN cause the fondant to split or crack - I got this tip from an instructor - during on the PME Sugarpaste module course. Cornflour we were  advised can also cause bulging - due to a chemical reaction in the cornstarch!. If fondant is too soft add SMALL amounts of icing (powered) sugar at a time. If too dry work in a little Crisco - taking care not to over work it.

 

Hope this helps!

Margaret393

I use cornstarch EVERY.SINGLE.TIME. and get bulges only when my dam isn't thick enough. That's it. It is a myth that it causes bulges or air bubbles.

I also use cornstarch when I work with fondant, it's never given me trouble.

 

I don't work with crusting buttercream, so I may be WAY off, but perhaps the fondant didn't have enough moisture to stick to the cake? If your fondant was dry to begin with, and the buttercream had already crusted, the air bubbles would make sense. The cracking could be as simple as overworked or dry fondant.

I also only use cornstarch and don't have problems with bubbles or bulges.  I do, however, have problems with Satin Ice.  I used it once on a large wedding cake, because I didn't have time to make my own, I will never do it again!  The problem wasn't bulging or bubbling, but just so dry, elephant skinned badly.
 

Before putting  the two cake layers together use a decorators bag to pipe a thick ring (a dam) around the top edge of the bottom layer then add your filling or frosting and put your second layer on. Everybody does it different, this was just the easiest way for me to explain what a dam is.

Did you let the cake settle before covering with fondant? (the weight of the fondant could have squashed something out there, maybe?)

Personally, I think the fondant you used was old. This happened to me once and made my cake a nightmare. I bought it on sale.....after I was done decorating my sad cake I dug the box out of the trash (I usually make my own MMF) but like I said, this was on sale..and sure enough it had expired a month ago! I did not notice anything wrong with it when I kneaded it or rolled it out ( I use the mat so no air could get to it) but when I transfered it onto the cake, it got hard almost instantly! I couldn't work it, smooth it or even get it to stick on wet buttercream! When I finally managed to get it down decently, I walked away from it, came back an hour later and it was hard enough to make a sound when you tapped on it..I had to throw it out...

 

I'm sorry this happened to your cake...it was really pretty.

I always make my own fondant and get air bubbles when I cover it over buttercream. My last cake I did a white chocolate ganache instead of the buttercream. Guess what happened?! No air bubbles!! Try using crisco instead of cornstarch...not sure what "reaction" that happens when you use cornstarch. 10x has cornstarch in it already.

Did you refrigerate the cake after applying the fondant?