Flattening Clay Tiles

How to Keep Your Tiles from Curling

Question, I've been trying to make my own clay tiles for table tops. The tiles are coming out fine, but during the drying some tiles curl on the edges.

What can I do to get the tiles to dry evenly?

Thanks,

Jeff

I consulted seven ceramic artists and guess what? I got seven pretty different answers!

I did find some common threads though. First I'll give you the suggestions they pretty much agreed on. Then I'll list some of the other tips that might be helpful.

To Prevent Tile Warping During Drying

1. Make sure the clay tiles are all the same thickness and no thinner than ¼ inch.

2. Air-dry them slowly and evenly. The consensus is that uneven drying is what causes warping. You want good air circulation but no drafts.

The goal is to arrange the clay tiles to dry in a way that allows moisture to leave at the same rate from both sides - easier said than done.

If you could suspend the tiles in mid-air to dry, every surface would have the same exposure to air. Since that is not possible, ceramicists have devised various methods to equalize air exposure or extract moisture at an even rate.

Method 1
Dry the tiles on wire racks (like refrigerator or closet shelves) with at east 4 inches of air space under each rack. Move the tiles slightly every couple of hours so that the racks touch different parts of each tile.

One artist bought a wire shelving kit which you assemble without tools. The pieces snap together with little joining pieces in any configuration you want. Each cube is 12 inches square, so when you stack them vertically, there are 12 inches of vertical air space between tiles.

Method 2
Flip the clay tiles frequently during the day and cover with them plastic during the night to retard drying when you are not able to flip them.

Method 3
This seems to be the most popular method. Sandwich the clay tiles between dry unpainted sheets of gypsum board (a.k.a drywall or sheetrock). This is paper covered plaster and it draws moisture from both surfaces at an even rate.

Tape the edges of the gypsum to keep bits of plaster from getting onto your tiles. (The gypsum can be dried out and reused a few times.)

If you choose Method 2 or 3, it may be necessary to take steps to slow edge drying since the edges would otherwise be exposed to air 100% of the drying time, while the sides would not be. This is more likely to be a problem with larger tiles.

You can coat the edges with wax resist or clear latex. Both are waterproof once dry and will prevent air evaporating from the edges.

Some ceramicists use strips of plastic wrap or plastic sheeting pressed against the edges. Others wedge scraps of clay against all the edges and remove them after drying.

To Prevent Warping During High-Firing

You specifically said the warping is occurring during drying, but if you encounter any warping during high-firing, the problem may be your clay body.

Clay for tiles should contain a lot of grog. Grog, also called firesand or chamotte, is a type of pre-fired clay or mineral that has been ground and screened to a specific particle size. It reduces shrinkage and aids even drying. Specifically our panel of experts recommended 200-mesh kyanite, prophyllite or molochite as good grog materials for clay tiles.