Principle 9. Preliminary anti-action

1. If it will be necessary to do an action with both harmful and useful effects, this action should be replaced with anti-actions to control harmful effects.
   Buffer a solution to prevent harm from extremes of pH.
2. Create beforehand stresses in an object that will oppose known undesirable working stresses later on.
   Pre-stress rebar before pouring concrete.
   Masking anything before harmful exposure: Use a lead apron on parts of the body not being exposed to X-rays. Use masking tape to protect the part of an object not being painted.