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5- If a piece of porcelain is thoroughly fused and more porcelain
added and fused, the first layer will be slightly overfused. In the pro-
cess of applying porcelain in layers and fusing each layer, the under-
lying layers will be slightly overfused and somewhat lighter in color.
6. A small mass of porcelain is more readily affected by heat than
a larger one, and as the size of the mass of porcelain increases just in
that ratio does the length of time required to fuse it increase.
7. Porcelains containing a large percentage of flux are more easily
affected by bubbles than those that are more nearly composed of the
basal ingredients.

Fig

8. It is more difficult to maintain the characteristic color of low
fusing than high fusing porcelains when held for a long time at the
maximum heat required to fuse them.
9. Low fusing porcelains are denser, have greater shrinkage and
less tensile strength than high fusing porcelains.
10. By repeatedly heating porcelain to the point of high biscuiting,
it will finally become fused and maintain its characteristic color.
11. High fusing porcelains shrink from 15 to 25 per cent., while
low fusing porcelains shrink from 20 to 35 per cent.
12. A coarsely ground porcelain fuses at a higher temperature and
shrinks less than one of the same formula finely ground.
13. The amount of shrinkage of any porcelain will in a measure be
dependent upon the consistency to which it is mixed, "and the density
to which it is condensed. The thin mi.xtures show more shrinkage than
those of a putty-like consistency.

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