I've been having an intermittent issue where my chocolate sticks to molds. It will always release around the edges but the middle (sometimes a large area, sometimes a small area) sticks to the mold. When I let the chocolate sit overnight, usually the surface is dull, but it snaps and appears to be tempered properly.
I think I've discovered that the temperature of the metal trays I'm placing the molds on influences whether this occurs or not. Has anyone else experienced this? What is the ideal temperature to keep my trays at when placing my molds onto them. I'm using custom food grade pvc molds and my bars are rather large at about 7.5 inches x 3.5 inches. Thanks in advance!
I'm suspicious about the "need" to preheat moulds. I moulded chocolate all Dec and Jan at 10-15°C temperatures, never preheated any moulds, and it worked great. Using Belcolade 73% dark.
Now that it's 25°C+ where I'm working I do one mould, then watch it as I start the next. Once it starts to look like it's firming up in spots, I put it in a bag, and then into the fridge for 10 minutes. Then I take it out again and let it sit for at least another 10 minutes. Again, no preheating.
Another thing I've found is that moulds have to be 100% clean before you put anything in them. I use a high cocoa butter chocolate which is probably not the best for moulding and it makes a mess of the mould no matter how well tempered it is. Chocolate comes right out looking great but the butter it leaves behind will ruin the next batch if I don't reclean it.
That's an interesting thought and certainly not beyond the realm of possibility that our molds aren't squeaky clean. I agree too that I dont think it's the temp of our molds as we've made chocolate in various temps and it always comes out fine in our first round of batches.
It's odd though. We set our molds on metal baking sheets on a rack in a walk-in fridge and when we pull them out they've fully released. We generally do two rounds and the first round always goes perfect. The second round is the one that gives us issue and the only variable is that we re-use the metal baking sheets. We've tried letting them sit out for a half an hour or sometimes an hour to get back to room temp. We've also tried warming them back up on the stove tops ever so slightly. But the only thing that's consistantly prevented the second round from sticking is putting a sheet of wax paper between the molds and the metal trays on the second round.
Must be an issue with the temperature of the metal trays? Maybe the wax paper creates enough of a barrier to prevent the chocolate from setting unevenly....
Since poo-pooing the notion of heating molds I have read that not doing so may cause the chocolate to 'stick' to the molds in such a way that they release nicely and look good but leave butter behind which is sufficient to mar the next round. Related experiment currently in progress...
Lee, I'm very curious about your results, I still haven't got a real clue to solve my sticking problem.
Someone advised me not to clean the moulds if possible, as the residual butter is supposed to help in the releasing of the next round. Confusing...
Sorry to take so long to return with results, been busy. However I can safely say that, for me at least, pre-warming molds is done in order to ensure cocoa butter left by the previous batch is liquid before new chocolate goes into the mold. As a liquid it becomes part of the new chocolate, whereas as a cool solid, it "sticks" to the new chocolate and doesn't integrate, becoming an off-color mark on the surface of the new chocolate once it leaves the mold.
Now that I've "discovered" this (after ignoring advice on pre-heating for several months lol) I do it with 100% of my molds and the dirty mold problem I had before has been solved 100%.
I too have had occasional sticking of pieces in a mold. Usually some will just fall right out, with others remaining behind. Banging the mold on the counter releases some more, but sometimes there are stubborn ones. I have tried cooling them an additional amount of time, but last week, by accident, I tried something more extreme, something most experts recommend against. Since I couldn't get the chocolates out and so had nothing to lose, I put the molds in the freezer, got distracted, forgot them for at least an hour. To my surprise and relief, the stubborn chocolates fell out in perfect shape. So, with some reluctance (because so many caution against it), I suggest that you might try the freezer as a last resort.
I should add that other molds filled at the same time as the problem ones released the chocolates without any issue. There are so many variables, so many possibilities, that I doubt we shall ever know the culprit for such random issues. The mold may be too warm or too cold. The chocolate may be untempered or overtempered. The mold may be too squeaky clean or dirty (some recommend not washing molds so as to leave a film of cocoa butter). Perhaps it's cocoa butter decorations that weren't properly tempered and so stick to the mold.
I can say with some certainty that I've never had a problem with molds being too clean lol. Unless it's a weird shape, chocolate will always come out of a mold if it's tempered right. In my experience :-D
I am wondering how you account for a mold filled with the same chocolate at virtually the same moment can have one cavity that releases immediately and a next-door one that does not. I can't see how the tempering can be right for one and not for the other.
Are the stubborn ones at in the middle of the mold? If some come out but not others, to me that says your cooling process is not happening evenly.
Re the warming of molds before filling: Nobody in this thread has mentioned the difficulty of doing so if the molds have been decorated with colored cocoa butter. I would be very reluctant to use any method of warming in this case as I would be afraid I would melt the decoration. It would theoretically be possible to warm the mold to the working temp of the chocolate/cocoa butter, but (I would think) it would be very tricky not to exceed that temp.