My vote is oil migration although it is happening relatively quickly but it seems the worst where the nuts are practically poking out of the bars and the oil doesn't seem to have far to go.
Sometimes heath inspectors get a bit overzealous and want everything sanitized. Chocolate does not support the growth of pathogenic bacteria and I never clean them unless seasonal molds being put away for next year (chocolate left on these molds picks up off flavours from the air) I scrape them before putting them away and playing around with plumbers-lye jeezus, one accidental episode in the eyes and you will be making brail chocolates. Corn cobb media polishes molds, the italians use this. Just heat befor casting with a hot air gun and do not polish just cast before the thin film cools.
For cleaning molds. I clean only if
A. I have a problem which shows up on the chocolate or
B. It is a seasonal mold that is being put away till next year. I wash in warm soapy water and rinse in an acid (vinegar would work but I use citric acid because I have it on hand) and air dry.
As for polishing there is corn cobb media that is made for polishing plastics and comes in 50 lb bags. I have a homemade "tumbler" (basically a drum on rollers). I put the molds inside and roll it over and over (plan to put a motor on it one day) and the corn cobb grit polishes and removes all traces of oil.
In regular use lightly warm the molds with your heat gun just enough to cause the film to liquefy before lining the molds. Don't worry it would take a whole lot longer to over heat the mold than most people would have patience for. Play the air over the mold maybe 5 at a time and then fill. I got this from Jean Pierre Wybau in a Seminar I attended in Montreal@ Callebaut Academy. It works wonders. If anything shows up after that you need to wash.
Also for the heat gun. Get a retractable cord and mount it on the ceiling of your shop and adjust it so it is just over your head. reach up pull it down use and tug and let it go back up over your head. Keeps the counters clear and gun accessable and never accidently droppped on the floor
Hope it helps
Dave
I have only ever had dry cases for 21 years. The word confection means preserved. If you are displaying at room temp you formulate for that.
