<html> <blockquote type=cite class=cite cite> Anyway for schools I consider using leather now. Have someone any experience on using it on brass pins without problems (dirtiness, wear of the pins or noise ?) </blockquote>Hi Isaac,                I have been using Kangaroo hide, available from Schaff under player supplies. It's fairly consistent at .050" thick. And less noisy than the product from Renner. We use it only for the balance rail hole, size the mortice carefully, with sizing cauls.  Then insert with bush master, for even depth.  they are flush cut to the button by using some custom made cauls, and a sharp razor. They are worth the effort, for heavy use. No problems with the old Yamaha brass pins. Now I can only speak for our dry climate.  There could be different results in areas of very high humidity, and industrial pollution??????? Regards Roger .        </html>