If specimens become too lightly stained, let them destain completely and return to step 4. End destaining by transfer to distilled water. It works more slowly and produces a better stain, but it takes time to learn to judge the progress of the destain. There is also little remedy for removing too much stain. Rinse the samples for several minutes in tap water.
Most tap water is alkaline enough to give the stain a blue-black tint.
This color shift can be used to judge the extent of destaining. If additional destain is desired, return to destaining solution. When destaining is satisfactory wash out the destain in distilled water for ca. Blue the preparation by washing for 5 minutes in saturated lithium carbonate solution. Some tap water is alkaline enough to blue the stain and make this step redundant.