- A discoloration that is not tangible, such as paint that cannot be removed, is not a barrier to the mikvah-water. Likewise, a substance that people are not at all particular about, such as the fire-blackened bottom of a pot, and the like, is not a barrier [and does not have to be removed prior to immersion]. (KitzurShulchan Aruch, 37).
2. It is acceptable to immerse a utensil by tying a string to it and lowering it into the water. However, one must be careful to leave the knot loose so that the water will also reach underneath the knot (Chasam Sofer).