crētŭla, ae, f. dim. [2. creta],
white clay, used for sealing , = terra sigillata, Cic. Verr. 2, 4, 26, § 58; Plin. 35, 7, 31, § 49.
crētula ae, f dim.creta, white clay, used for sealing : signum in cretulā. ...
An Elementary Latin Dictionary