Tile troubleshooting

Glaze rheology

Glaze rheology must be adjusted to suit the application device (bell, double disc, airless spraygun). In some cases the glaze isn't liquid enough and won't apply properly on the tiles, or the pumps won't work properly. This is due to high viscosity and/or to a high yield value. One solution is to adjust the water and/or additive content. To keep the same slip density, switching to a more liquid kaolin or clay can be the solution.

Glaze kaolins:

• UK: Kaoshine CNL80
• Brazil: Kaoshine RC 70, Kaoshine RC 75
• Indonesia: Kaoshine ID33

Engobe ball clays:

• UK: Hywite Superb

Glaze sedimentation

Glaze is mostly composed of frit and kaolin. During preparation and storage the glaze can sediment more or less quickly depending on the kaolin used. The settled cake at the bottom of the tank will be more or less difficult to stir back to suspension. These issues can be resolved by using the appropriate kaolin.

High suspension kaolins:

• UK: Grolleg
• France: Kaolinor 1C, Kerbrient

Residue on sieve

During engobe preparation, and depending on the milling stage and mesh size used on the sieve, residue can be found on the sieves. If the quantity of residue is too high, a low residue ball clay will help to reduce it.

• UK: Hymod HSM-E, Hyplas prime

The drying time of glaze and engobe must be adjusted to obtain a mat surface just before the following application.

If the drying of engobe or glaze is too quick before the next application, the glaze will be absorbed too fast leading possibly to holes in the layer and a gradient of particle size and composition across the layer itself.

If the glaze dries too slowly, at the decoration step it can lead to a loss of ink definition due to expansion of the ink dots on a wet surface.

To increase drying time of engobes:

• UK: Hymod HSM-E, Hyplas 64
• US: Old mine #4
• France: FMT

To reduce drying time of engobes:

• Thailand: Whiteplas N11
• UK: Hywite premium
• Egypt: ICE Hywite Premium
• India: Certiwhite

To increase drying time of glaze:

• UK: Grolleg

To reduce drying time of glaze:

• UK: Kaoshine CNL 80
• US: Allen G
• Brazil: Kaoshine RC70

Our experts can also help resolve glaze defects encountered after firing, for example: low gloss, low opacity, bubbles and pinholes, dimples, black spots, crazing and peeling, and waviness.

Whatever issues and challenges you’re facing in the production of tiles, get in touch to hear how our experts could help resolve them and take your results to new levels.