Mat = Material

composing the mould or part. Abbreviations:

Al = Aluminum of food grade. (Ordinary grade contains Arsenic and other toxins.)
Ag = Silver plate to give finer detail. So thin that a reddish color of underlying Cu often shows through. Produced by                         LG.
Au = Gold, poured into Bra jewelry moulds
Ba = Bakelite
Bi = Bismuth hardens Pewter but lowers the melting point and makes it brittle
Bra = Brass[Cu+Sn]
Bro = Bronze [Çu+Zn] Takes fine sharp detail. Wears for generations so used for master moulds. War shortages of                         Bro caused Fe to be substituted for much or all of the master moulds Bro was still used for important                         details such as faces (see Swedish master moulds)[WSS B]
Ca = Calcined gypsum, plaster
Cer = Ceramic
CN = Wood, chestnut
Comp = composition (TM used Pe until 1940 then Sp= "Spelter" (Sn+Zn) still considered toxic by FDA)
Cri = Crinoplast , a clear plastic
Cu = Copper. Gives pewter greater strength and smoothness Acids corrodes to highly toxic verdi gris so should             always be plated over.
Fe = Iron. Safe with food but doesn't give good detail tends to crumble and rusts if not kept dry. (magnetic)
FO = Font [Fe+ 2% C] eg Eiffel tower
G = Glass
Ki = Kirksite (Aluminum and Zinc, ZAMAK)
Mak = Makrolon
Ni = Nickel (edge drawn across white paper makes a black mark)
Pb = Lead. Makes pewter gray. Forbidden in USA and France since WWII because toxic. Black Pewter [40% Pb)                         is used for organ pipes and candle sticks.
Pe = Pewter Only English has a separate word for Pewter.(Sn+ Cu, or Bi, Sb, Pb) toxic per FDA. In NY holes were                         drilled in Ice Cream moulds so they could only be used as ornaments. 1998,Mr Boazis last owner of                         LG, "LG used 98%Sn + 2% Cu".
Pl = Plastic
P = Platinol (Nickel clad steel) made during WW II by Vereinigk Deutsche Nickelwerke Schwerteduring.[V92: 3]
Plex = Plexiglas
Poly = Policarbonate
PVÇ = Polyvinychloride
Ru = Rubber
S = Sulfur (melting point 112.8, too hot for molding living tissue)
Sb = Antimony Forbidden in France since WWII as toxic. 1% hardens tin and makes it gray
Si = Silicone. Only medical and food grade are not toxic.
Sn = Tin or tin plate and for undetermined sheet metal or plating [please see Dorchy 1988 which has the usual metal for some makers]
So = Soapstone
SS = Stainless Steel (has the best ductility; erchson #-but poor heat conductivity)[Fr inoxydable]Fe +0.8% C+Cr]
St = Steel
Syn = Synthetic
T = Terra cotta
W = Wood
Wax
WR= wood resin
Zn = Zinc (toxic per FDA)

Plating

1. Dipping: Bra, Cu or St dipped into liquid Sn
2. Cladding, Annealing: Sheets, [ 1x0.5 meter] "Plates" [hence "Platting} of the two metals(Cu plated w Ni; St plated                         w Ni) were heated to 800° in inert gas (Nitrogen) to prevent oxidation Then rolled between heated                         rollers under pressure of tons. (only 3-4/year became unstuck).
3. Electroplating 1920's: The object of St is placed in a vat with sulfuric acid. An anode of the plating metal. Ni is                         hung on the side of the vat. An electric current is passed, carrying the Ni to the St providing a smooth,                         even, continuous coating.