Because of its thermoplastic properties, shellac can soften in warm temperatures and requires attentive handling. A French polished instrument, in its case, should never be left in the sun, warm automobile or any very warm location since the lining of the case may stick or leave impressions on the finish. Even the warmth of an arm in contact with the finish while playing in very warm conditions may leave impressions. A soft insulating cloth should be used at the point of contact. This finish also is susceptible to damage by alcohol and perspiration.
Nitrocellulose lacquers are also suseptible to damage when exposed to very warm conditions.
Limit the use of commercially prepared polishes on the French polish finish. Wipe regularly and carefully with a soft clean cloth to maintain its luster. While this finish is susceptible to damage, it is very easily restored. Periodic restoration should be expected. Always consult the maker or a legitimate expert for restoration.