Crawling
Glaze crawling, is a defect that occurs during firing when the glaze shrinks and separates from the surface in certain areas, leaving bare or uncovered parts. This phenomenon can be caused by several reasons, such as the presence of impurities (such as grease, dust or oils) on the surface of the piece before the application of the glaze, or by an incompatibility between the chemical composition of the glaze and other materials of the piece.
Crawling not only affects the aesthetics of the piece, creating irregular and less attractive areas, but can also compromise its functionality, especially on objects that require impermeability such as bowls, plates or pitchers. The lack of uniform glaze coverage can increase liquid absorption and reduce the durability of the piece, which is particularly problematic in tableware and cookware.
Although generally considered a defect, they are sometimes used intentionally to create unique decorative effects. By manipulating firing conditions or adjusting glaze formulations, it is possible to generate controlled pull-outs that add interesting textures and contrasts to pieces, integrating the error as part of the artistic design.Interesting Fact
Some specific patterns of crawling are characteristic of certain periods, regions or production techniques, allowing collectors and archaeologists to identify the provenance and authenticity of a piece. For example, certain styles of crawling in Spanish Golden Age ceramics are highly valued for their rarity and beauty, reflecting the mastery of the artisans of the time.Helpful Tip
To minimize the risk of removal, it is essential to meticulously clean the pieces before applying the glaze. Use a slightly damp sponge to remove any oil residue, dust or impurities and, if necessary, apply an engobe base to improve the adhesion of the glaze to the surface. In addition, adjust the glaze formulation to ensure optimum compatibility with the clay body used, thus avoiding separation during firing.
