Mayco Classic Crackle Glaze #101 - Transparent Crackle - 4 Ounce Jar Classic Crackles add a level of sophistication and dimension to your designs. The cracked effect has traditionally been used to create a vintage or antique appeal. Increase complexity by using in combination with other glazes or design work. Classic Crackles develop subtle surface cracks in the finished glaze. This cracked effect has traditionally been used on home dcor pieces by designers looking to create a vintage or antiqued appeal to their pottery. AP Certified Non-Toxic. Low fire (cone 06) glaze. Made in USA.