Problems With Tiles
by: Guest
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TILES AND THEIR PROBLEMS FOR DECORATING BY HAND.
A tile is a flat ceramic shape. They are designed to fit together to cover an even surface such as walls, floors, table tops, pictures, etc. They can be industrially bought or handmade and are normally square or rectangular but can be any shape or size.
For our business we use industrially made red terracotta bisque tiles, clay that has been fired and not decorated in any way. In the past, industrial tile production consisted of two stages: the making of the bisque and the decoration, often by two different firms. This has changed they are now made with non-stop machinery, which shapes, dries, decorates and fires them. Before there were many small firms that made bisque tiles with their different trademarks, qualities, sizes and colors. Nowadays the choice of firms is limited and what is worse the industrial process of making tiles has changed they are now made to be stronger, lighter and cheaper for commercial reasons. This has brought us many problems and under a) and b) I will describe and explain how we have coped with the two worst ones.
I am a practical creamiest not technical and I do not understand the technical change tiles have gone and are going though but since about 1985 they have got worse and are affecting the method we use, the colours, textures, outlines and most important of all, the glazed surface.
Our method for decorating is known as Majolica and what distinguishes this technique from others is that the opaque glaze-base and the decoration are fired together. It needs two firings, the first is to fire the clay, the clay turns into a ceramic when fired at 600 Cº or more, the higher temperature, the stronger it becomes and it changes into a material that is solid, breakable but still porous and is know as bisque. For the second firing the bisque fired pieces are covered with a lair of an opaque, white, glaze-base, the raw glaze-base is then decorated with metallic oxide glaze colors that have been prepared with a transparent glaze and water. When finished they are fired together to vitrify at 980ºC. The vitrifying makes the glaze-base an opaque lair of glass and this stops the bisque being porous and leave a brightly colored, glossy, smooth surface that maintains and enhances the lines, colors and quality of the decoration
PROBLEMS
a) The tiles when decorated and fired are left with a rough, hard surface, as though hundreds of bit of fine sand had been added.
We had been preparing tiles in the same way for twelve or more years; applying the glaze-base, cleaning them, piling them up by pairs, face to face, on top of each other, then leaving them together for days, weeks or even months before decorating. Then the firm we bought from stopped producing and we had to find another one. The new tiles had a strange reaction as they came out in a rash, mainly round the edges; very small hard spots, which did not go away when fired and damaged the work enough to make it non saleable. We just could not understand what was happening, and suffered the consequences as hundreds had to be thrown away. By sheer accident we found the solution, making two pictures for the same client; we laid out one on the tile stand to dry off, so we could start to work and the other we left piled up. After four days when we wanted to start to paint the second one, it had the disease. What causes it we do not know, but how to avoid it we do! Now one long wall, in our studio corridor, has narrow movable shelves, where all the tiles prepared with the glaze-base are laid out and left to dry separately without touching each other. When the glaze-base and the tiles are dry they can be stored in piles. We also notice this disease appears slightly in winter when the studio is colder and the drying period is longer.
I have been told this happens because the new processes of producing tiles makes them stronger and this means they cannot absorb water so when they are piled up face to face (base on top of base) the water can not escape and they cannot dry. The worst tile is 6 x 6 in (15x15cm) as it is the most commercial one, it is so strong and hard, when cover with the glaze-base it can take up to 24 hours to dry with the old tiles this took about 2 hours!
b) When fired the glaze base is semi-mate and should be a glossy, varnished surface.
When we started using the new make of tiles we found that when fired to the correct heat the glaze surface was semi-matte, as if not completely fired. The first way we found to avoid this was to spray the finished work, before firing, with a layer of transparent glaze. The method was expensive and unhealthy. After doing this for about six months we realized this problem was because the bisque tiles we brought were under fired, we now we fire them all to 980 Cº before starting to decorate. This is only needed for industrial made tiles all the other objects we use, which are handmade tiles, plates and jars do not need it.
I think that consumers should be protected as a firm can change its way of production and you can buy without being advised. Before ordering a product one should be given its formula to see if there has been any changes in its structure since you last order.
There are two things I would like to know –
1) Can anyone explain to me in simple technical terms the changes that have accrued in making tiles, so when I buy from a firm I know what I am buying and can explain what I want!
2) I will be very grateful to anyone who can give me names and addresses of firms in Europe that produce “good” red clay bisque tiles.
Our business is in Barcelona, Spain and we can buy and use good handmade or semi handmade tiles but they are thicker and heavier, these tiles can be used should clients require it but it increases prices of firing packing and transport. The sizes we need are 15x15cm, 7.5x15cm, 7.5x7.5cm, 7,5x20, 20x20cm and 15x20cm and between 0,7 to 0,8mm in depth and made with the same materials. We need about 6,000 of 15x15cm and about 1000 of each the other sizes every year.
About the Author
Susan Mussi - I am English, married to a Catalan surgeon and have lived and worked in Please look at our Web: www.ceramisbensu.com and you will see how we work
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