Ceramic body tiles are not as strong as vitrified body tiles. So, it is prone to quality issues. The most common issues are as under:
After production, the ceramic body tends to absorb moisture and bend. It is difficult to fix a bent tile.
i) Due to improper temperature, a tile during the firing process.
ii) Due to improper pressure is given to raw biscuits (body).
i) Most wall factories keep little plus bend. Which settles to be flat in a few days after cooling down.
ii) Some European equipment companies make DICO Planar. This helps to check flatness (bending). The factory just needs to enter the range of parameters. The planar machine will mark every single tile which goes beyond that limit.
Glaze surface is waterproof but what about the body? The ceramic body is more porous. Once you fix a tile, water can accumulate beneath the glaze layer. It gets locked-in. This leaves random watermarks on the surface & gives an ugly look to your walls.
Most quality tiles factories, these days, use waterproof engobe beneath the glaze layer. So the tile body will absorb the water but the watermark will NOT visible. Remember you need to ask for a waterproof tile to get one!
Scratches are more common on a glossy surface.
i) At the end of the kiln (out-table) tiles are sliding onto each other. Tiles are hot at this stage and prone to get deep scratches.
ii) During packing inside the boxes tiles can get scratches.
i) Apply backwash (a solution of calcium carbonate) during production on the backside of the tile. Small partials of this white powder give a smooth interface to avoid scratches.
ii) Connect the kiln out-table to the sizing area. This way tiles will not get deep scratches. Some factories like Coreal, Lavish, Colortile follow this practice to make good quality tiles.
Above quality issues, we can avoid in vitrified body tiles. But in the case of the vitrified body, we have seen dull edge polishing issue if a factory is not watchful to the polishing area.
Dull edge polishing
Reason: Polished vitrified tiles pass through the polishing area. During this abrasive head moves on a tile surface from end-to-end. Some factories used to do sizing (rectification) BEFORE polishing. This caused some part of the edge left unpolished.
Solutions: i) If they do sizing AFTER polishing this problem can be avoided to some extend. ii) the polishing head movement area should be little more than then tile’s surface. This makes sure polishing heads give equal pressure at the edges. This minimizes the issue.