If stubborn residues remain after use it is recommended to full the glasses with a tepid mixture of 50 % vinegar or citric acid (e.g. lemon juice) and 50 % water (if necessary, add uncooked rice and shake). After this mixture has worked for 24 hours, rinse everything out with warm water.
A grey tinge that appears if glasses are not used for a long time can be removed by rubbing with a linen cloth or by rinsing.
What to do with blind glasses?
Take a cloth moistened with ammoniac.
Because crystal reacts very sensitively to great temperature fluctuations it is advisable not to treat these glasses with very cold or hot water.