"So it is," said Fred. "The baking made the clay porous.""Now listen," he added. "We want our bricks to be porous, so that any water that gets into them may drain out. But our cups and saucers, jugs and basins, and most of our earthenware things have to hold water. They must not be porous, or the water would run away.""But you told me they were all porous after they had been baked." said Norah.
"Don"t you be in a hurry, little sister," said Fred. "Here is a flowerpot, and here is a teacup. The teacup was as rough as the flowerpot at first, but it is smooth and shiny like glass now. We say it is glazed. This glaze is not porous, and liquids will not pass through it. After the cup is baked it is dipped into the glazing mixture and baked again. When it comes out of the oven this time it is smooth, shiny, and not porous, just as you see it now.""What clever boys you are," said Norah. "You are very good to tell me all these fine things."SUMMARY
Vessels made of baked clay are porous. Bricks and ?owerpots are porous. Cups and saucers, plates and dishes, basins and jugs are glazed, to make them smooth and shiny like glass. After this they are not porous.
The Cat"s Big Cousins-The Lion
