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A small tile decorating company diagnoses problems with commercial bisque tiles and seeks help to find the type of tiles available in the past.
We decorate tiles by hand using the Majolica method. We thus apply a glaze-base to bisque fired tiles, decorate them and then fire the base and decoration together. We have been having great problems with the industrial-made tiles we buy (there is no problem with hand or semi handmade tile). We normally use handmade ones but need to buy commercial ones when a client requires. The industrial-made tiles are much more expensive and they are thicker and heavier so this doubles the price of transport and firing.
INDUSTRIALLY MADE TILES AND THEIR PROBLEMS: The tiles we use are made of red terracotta clay; bisque fired, well finished off. The use three main sizes, 6x6in (15x15cm), 8x8in (20x20cm) and 8x6in (20x15cm); each one can be brought with a choice of thickness. In the past there were many different types and makes of industrial-made tiles and the production consisted of two stages: the making of the bisque and the decoration. Often by two different firms, but this is no more, tiles are made with non-stop machinery. It shapes, dries, decorates and fires them. Before there were many small firms that made tiles with their different trademarks, qualities, sizes and colors. Nowadays the choice of firms is very limited, and what is worse, the process of making them has changed, as they are now made with industrial methods to make them stronger, lighter and cheaper for commercial reasons. This has brought us many new problems; I will describe them and explain how we have solved these problems.
1) 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, and leaving them 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: they came out in a rash, mainly round the edges; very small hard spots, which did not go away and when fired, 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, we found it had the 'disease'. What causes it we do not know, but how to avoid it we did! Now one long wall, in our studio corridor, has narrow movable shelves, from top to bottom where all the tiles 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 on top of each other, as before.
The first photo shows one tile from a picture of 20 where the whole surface is affected; looking closely the small white spots can be seen.
3) At the same time we started having problems with the manganese - all the outlines started blistering, we had not changed the make or type of color. Of course any poor client knows when a product he buys has changed. The solution to this was to stop using manganese and we now use 1 part brown-red with 1 part dark brown.
4) The photo shows two tiles, the back of the old and the front of the new, just seeing the different colors shows the difference in quality also the contours on the back of the old ones are much easier to clean, the new ones are made with small indented lines (which doubles the work).
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