I have never lost a cartouche yet as you are not scrubbing the stocks with a hard brush when using a tooth brush. Folks here know I have done allot of stocks without harming them and I understand what your concerns are.

In the case of a dark stock like you are talking about you will need a stripper and the tooth brush method. But if not comfortable then leave them as they are, you can always clean them later if you feel the need. Rick Bicon