Techniques for using (Polish) Pickle Pots?

Question

I have a pair of Polish Pickle Pots, something like this:

But when I use them, I am yet to get good results. Mainly I've tried using them for sauerkraut (maybe 6 times), pickled beetroot (once) and miso (once). But always the content goes mouldy.

Even with plenty enough brine from the content, and the stones hold the cabbage below the brine level, then the stones themselves go mouldy (black mould).

Is there something I'm missing? My pickles in plastic, with water-filled bottles or other plastic bags as weights never seem to have the same trouble.

Is there a special technique for using these pots? Is it mandatory to fill the air-lock around the lid (I do)? With water?

Answer 1

Since part of the problem is probably that the pot and weights are "infected" with mold spores, one thing I would suggest is heat-sterilizing the pot and the weights to eliminate any spores that might be embedded in the raw clay of the weights or any cracks in the glaze.

Here's how:

1. Place the pot, lid, and weights in a cold oven
2. Heat the oven to 180C/350F and keep it there for at least 1/2 hour
3. Allow the pot, lid, and weights to cool slowly, possibly by leaving them in the oven while it cools