An engobe is a ceramic coating formulated to work with the underlying body and, where applicable, the glaze above it.
For manufacturers evaluating bentonite, the useful question is how the additive affects the coating throughout preparation, application, drying and firing.
Define the Application StageIdentify whether the engobe is applied to a wet, partly dried, dry or fired body.
The substrate’s moisture and condition influence the evaluation. A formulation approved at one application stage should not automatically be transferred to another.
Evaluate Suspension and Application Compare settling, ease of remixing and flow under the intended process.
Check whether the coating produces consistent coverage and thickness. A stable container sample should also remain suitable for spraying, dipping or another specified application method.
Commercial clay-based ceramic additives are designed for viscosity and stability control, confirming the importance of matching rheology to the production process.
Assess the Dry Coating Observe adhesion, powdering and cracking after drying.
Keep applied thickness and substrate condition consistent across trials. Changes in water demand or drying behaviour can influence the result.
Bentonite should be evaluated as part of the complete engobe formula, including other clays, binders and dispersants.
Check Body–Engobe CompatibilityFire coated specimens using the intended cycle.
Record peeling, cracking, surface appearance and interaction with the glaze. Compare drying and firing behaviour because satisfactory wet application does not establish compatibility after firing.
Build a Practical Approval ProcedureA useful trial includes a control formulation, documented addition levels and repeated coated samples.
HERMANO provides bentonite for ceramic application evaluation. Share your engobe composition, application stage and current coating problem to discuss samples and relevant material information.
