Glaziers' putty is made of whiting and oil. The whiting should be in the form of a very dry fine powder; it should be specially dried for the purpose, and passed through a sieve of 45 holes to the inch, and then mixed with as much raw linseed oil as will form it into stiff paste; this, after being well kneaded, should be left for 12 hours, and worked up in small pieces till quite smooth. It should be kept in a glazed pan and covered with a wet cloth. If putty becomes hard and dry, it can be restored by heating it and working it up again while hot. For special purposes, white-lead is sometimes mixed with the whiting, or the putty is made of white-lead and litharge entirely.