Tom I live in a tropical country and in a very hot city: Rio de Janeiro In any season, there are sunny days so the problem can be solved. Normally first we scrape the keys and after we put in they to get hot and then, we use hydrogenperoksyd (10 %) to make them white We may to find it in beauty supply shops. If it is very sunny, then the keys will be ready in half an hour. If after the process, some keys still remain yellow, are some still yellow then you may add more H2O2 to solve the problem If the ivory is very thin, then a more diluted solution of H2O2 must be used. By making sure that the keys are properly scraped, you will ensure good result with smaller amount of H2O2 even if the is not very sunny. Rogerio Cunha IC Member of The Piano Technicians Guild http://hpp.ajato.com.br/rogeriocunha
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