To avoid stains and mold marks on the chocolate bar after hardening warm up the mold a bit with a heat gun before pouring. Also let the mold stay at a room temperature for 3-5 minutes before putting it in a fridge so crystallization will run more even.
The more water in the filling — the poorer its shelf life. If you want to get a candy with a long shelf life (4 months or more) without increasing the proportion of sugars and with no preservatives inside use fat fillings.
If water accidentally gets into the melted chocolate and it begins to thicken, you can't restore it. But you can make an excellent chocolate cream or ganache by adding warm water with constant stirring.
Infusion can be hot and cold cooking. The first one takes a minimum of time (up to 15 minutes). The second requires 10 hours or more, but such a method guarantees the conservation of all the healthy features and active components of the ingredient.
Cream expiration date is unrelated to a microbiology disturbance. It's bound with chemical enzymatic processes (rancidity), which proceed even in a sealed Tetra Pak. That's why mould absence after the expiration date doesn't indicate that cream is ready for use.
Sugar has the ability of reverse crystallization after dissolving in water. To avoid this in the finished candy and keep the consistency of the filling homogeneous and smooth, glucose syrup is added to it as an anti-crystallizer.