The first Breyer "porcelains" were "cold cast" porcelains, which are actually resins. Being cast from resin, these horses are solid and quite heavy, which is impossible for a true fired porcelain--that large a piece of solid porcelain would explode in the kiln, rather memorably. To be called a "cold-cast porcelain," porcelain dust is added to the resin to give it the porcelain look, and the piece is never fired, just molded.
The first five cold casts produced included the San Domingo mold, called "Spotted Bear," which was sold by Sears in 1991, the Sham mold, "Galaxias," sold by JC Penney's in 1991, the Misty mold, "Misty," sold by JC Penney's in 1992, the Sherman Morgan mold, "Fashionably Late, " sold by Sears in 1992, and the Secretariat mold, "Secretariat," sold by Sears in 1992.
The current Breyer porcelains, which they call "fine"
porcelains, are indeed fired, regular china pieces. They are hollow
and have the airhole required to survive kiln temperatures and
all have been sculpted by Kathleen Moody.
(Information about Breyer's porcelain and coldcast porcelain
horses was obtained from Sue
Stewart, Daphne R. Macpherson and Peri
Riggins.)
Photo credits: Porcelain Horse in Armor,