Did some casting the last few days.
I WD40 my molds before putting then away.
Need to degrease and clean before casting.
Normally use soap and not water with a tooth brush.
Don't know why I tried it, but I sprayed it with Windex glass cleaner before scrubbing with soap first.
Seemed to work really well.
I'm thinking the ammonia cut through the grime and WD40, while the soap helped washed it away.
Try it and see what you think.