When a sample changes, keep one untouched reference card in the record. The control gives the next comparison a stable starting point instead of forcing a reviewer to reconstruct what changed from memory.
Change one question at a time
Write the purpose of the new sample before preparing it, then label the reference and the changed version clearly. This makes the outcome easier to discuss without implying a final setting, certified result, or broad material recommendation.
For more compact-project workflow notes, browse /updates/ before preparing a sample.