User blog comment:Xilinoc/Ch. 567 (Rukia be like "I ain't even scared though")/@comment-10554972-20140205203959/@comment-5693502-20140206091207

It definitely does not turn Rukia into ice; it doesn't produce ice at all. It lowers temperatures. Makes things colder. Freezes things.

The molecules of her body freeze, they don't become ice. Sode no Shirayuki freezes water molecules, ice appears as a result.