There are 2 ceramic shops in Krakow - they will probably know if there are no language barriers:
sklep"Świat gliny"
ul.Kremerowska 2
31-130 KRAKÓW
tel. 12 623-74-83
kom. 606710027
sklep czynny pn-pt 10-17
Chodkiewicza 17
Kraków
31-532
krakow@keramos.pl
(12) 292 18 42
516 147 939
godziny otwarcia sklepu:
pn-pt 10:00 - 17:00
sb 10:00 - 13:00