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
Gift white elephant. One means of reducing the mismatch between the buyer and receivers' tastes is advance coordination, often undertaken in the form of a wedding registry or Christmas list. Wedding registries in particular are often kept at a single store, which can designate the exact items to be purchased (resulting in matching housewares), and to coordinate purchases so the same gift is not purchased by different guests. One study found that wedding guests who departed from the registry typically did so because they wished to signal a closer relationship to the couple by personalizing a gift, and also found that