Contrary to the static contributed by some subscribers, good old Rudad
contacted a non-subscriber, who contributed this response to my earlier tile
question.

Christopher (response from Eric Astrachan of Artfind Tile follows)

<<Our good friend Rudy sent us your E-mail. We have a collection of tile from
the late 1800's and also manufacture tile. The answers to your questions
follow:

The transparent glassy surface of "turn of the century tile" was accomplished
with glazes rich in lead. Similar to lead crystal, the lead and glass
compounds have a refractive index that is much greater than ordinary glass
and hence they reflect light more sharply.

These glazes fell out of favor for many reasons: 1) The raw glazes (before
firing) were toxic - lead poisoning in the tileworks of the late 1800's was
common. 2) The glazes are softer and more easily scratched. 3) They could not
be fired at the high temperatures used today for porcelain and other high
temperature tile bodies.

Tile shapes were formerly created in screw press type molds. The sharp edges
were similar to cut stone and worked well with mortar bed installations
(where the mortar squeezed between the tiles and formed the "grout".

The modern "pillow edge or cushion edge" works better in dust press molds
(where clay dust is pressed under many tons of pressure to make the tile
body). Also the cushion edge allows for easier installation using tile
thinset cement in lieu of the older mortar bed installation method.

For more information on historical tiles, may I suggest you contact the Tile
Heritage Foundation (Joe Taylor). This is an extraordinary organization with
huge amounts of information on American tile. Their phone number is
707-431-8455. Should the area code have changed, they are located in
Healdsburg, CA. If you should have any trouble reaching them, please do not
hesistate to contact me.

My E-mail is TILESAFT @ AOL.com.

Regards,

Eric Astrachan
Artfind Tile