Might be wrong, but I believe I have read on this forum that you should not use rubbing alcohol on your blocks. It can cause them to craze over time.
Someone with more experience can verify if I am remembering correctly or not.
The best cleaner for blocks is just water and a bit of dish detergent, then rinse.
Congratulations on trying the cling mount stamps. You might just find that you really like them. Easy to store and give just as nice an impression as wood mount.