Tin pest related problems such as tin whiskers. At 13.2 °C (about 56 °F) and below, pure tin transforms from the silvery, ductile metallic allotrope of β-form "white tin" to the brittle, nonmetallic, α-form "grey tin" with a diamond cubic structure. The transformation is slow to initiate due to a high activation energy but the presence of germanium (or crystal structures of similar form and size) or very low temperatures of roughly −30 °C aids the initiation. There is also a large volume increase of about 27% associated with the phase change to the nonmetallic low temperature allotrope. This frequently makes tin
EMLL 15th Anniversary Show at Arena Modelo in 1933 and returned to that building in 1937 through 1943. From 1934 through 1936 EMLL rented Arena Nacional for their shows, but in 1944 they began holding their anniversary shows at Arena Coliseo, an arena they owned. From 1944 through 1955 EMLL held all their anniversary shows at Arena Coliseo. Traditionally EMLL/CMLL holds their major events on Friday Nights, replacing their regularly scheduled "Super Viernes" show. The event featured an undetermined number of professional wrestling matches with different wrestlers involved in pre-existing scripted feuds, plots and storylines. Wrestlers were portrayed as either heels (referred to as