High Water Absorption: Insufficient Flux in Ceramic Bodies

If your fired tiles consistently fail to meet the target water absorption specification — for example, porcelain tiles showing 0.8% when the target is below 0.5%, or floor tiles at 4% when the target is below 3% — the most likely cause is insufficient flux in the body formulation.

Symptom

If your fired tiles consistently fail to meet the target water absorption specif

Root Cause (Flux-Related)

The body is not vitrifying enough to close the open porosity. Solutions using our products: increase nepheline content by 3-5% to boost flux power; or switch from feldspar to nepheline without reducing percentage (nepheline provides 20-30% more flux, effectively increasing the flux dosage); or switch from K100 (100 mesh) to K200 (200 mesh) — the finer particle size reacts faster, achieving better vitrification in fast-firing kilns without changing the formulation weight

Solution

Before changing formulations, also check: is your kiln reaching the target peak temperature? Is the soak time at peak temperature sufficient? Has your clay supply changed (different clay can require different flux levels)? Our technical team can help you determine whether the problem is formulation, kiln settings, or raw material variation.

Understanding This Defect

The body is not vitrifying enough to close the open porosity. Solutions using our products: increase nepheline content by 3-5% to boost flux power; or switch from feldspar to nepheline without reducing percentage (nepheline provides 20-30% more flux, effectively increasing the flux dosage); or switch from K100 (100 mesh) to K200 (200 mesh) — the finer particle size reacts faster, achieving better vitrification in fast-firing kilns without changing the formulation weight. Before changing formulations, also check: is your kiln reaching the target peak temperature? Is the soak time at peak temperature sufficient? Has your clay supply changed (different clay can require different flux levels)? Our technical team can help you determine whether the problem is formulation, kiln settings, or raw material variation..