After I decorate and the cake sits, I notice shiny oil/grease gathering at the bottom border of the cake, around all sides. I can't tell if it's from the cake or from the frosting.
I recently reduced the canola oil in my cakes to 75% the original volume to deal with some moisture issues, but I'm still seeing this oil seep out. It's not excessive - but I can certainly notice it. And on one cake it was bad enough that when the customer held it up at an angle to take a picture the cake actually started to slide off the board!
Happen to anyone else?
Oh my! That's never happened to me before. What's the total amount of oil you're using and what kind of frosting do you make?
I have had issues with my buttercream weeping which is more noticeable in warmer temperatures, but I have noticed it on occasion at room temperature. I use a variation of Indydebi's using a mixture of shortening and butter. The times that I have had issues are only when I have used Keller's brand butter, so I refuse to use that brand anymore.
I hope you are able to find the source of your problem.
I reduced the oil down to 45g plus 60g butter. The frosting has a pound of butter and a pound of shortening. Sometimes I think my butter is too soft when I make the frosting but I'm not sure that matters (?)
It's really frustrating. It pools enough that if I stick the corner of a paper towel near the border I can absorb it.
Oil separates out of the buttercream when it's on the counter as well, at room temperature in its container. That takes a quick stir to fix....but on the cake is a different story
I had problems with weeping buttercream when crisco went trans fat free. It got better when I switched to store brand shortening that still had trans fat.