I can't leave my things in the kitchen once I've finished making soap. However, I find that some of the plastic measuring cups don't come clean. I use Dawn Ultra yet they still have a greasy coating once dry. One of the hard plastic cups that had lye in it has a fine line crack going up the back side. After cutting my soap using the pictured cutter, how do I clean the soap out of the bottom grooves. I lused a straight edge and slide it sideways, but there is still soap in there.