Putty. This is prepared by mixing fine whiting with linseed oil or linseed-oil varnish. The whiting should be passed through a sieve of 42 meshes to the inch. It should be perfectly dry before sifting, and be thoroughly incorporated with the oil.
As the work of kneading large masses with the hands or feet must be continued for a long time in order to obtain an entirely uniform product, and is consequently very laborious, it is recommended to use the following contrivance:
Two wooden rollers rest in a suitable frame, and can be brought together or removed from each other by means of two screws. When the mixture of whiting and linseed oil is of sufficient consistency to allow kneading, it is fashioned into a cylinder and rolled out between the above rollers to a long, thin band, which is caught in a vessel. The band is balled together, the ball reformed into a cylinder, and the latter again passed through the rollers, the operation of balling and rolling being continued until a uniform mass is obtained.
The finished product should be kept in oiled paper or under water. White lead is sometimes mixed with the putty, and other pigments to give color as desired. Hard putty may be softened by rolling between the hands.
French putty. Boil 7 lbs. of linseed oil with 4 lbs. of burnt umber for 2 hours. Then add 10 lbs. of white lead and 5½ lbs. of chalk.
Soft putty. Whiting 20 lbs., white lead 2 lbs., linseed oil and olive oil 1 gill each.
Mix the whiting and the white lead with the necessary quantity of linseed oil, to render the putty of the proper consistence, the olive oil being added to the linseed oil before kneading. The object of using olive oil is to prevent the white lead from hardening, and it preserves the putty in a state sufficiently soft to adhere at all times, and not, by getting hard and cracking off, suffering the wet to enter, as is often the case with ordinary hard putty.
Litharge cement. By mixing litharge reduced to a fine powder with linseed oil, a yellow cement is obtained which gradually solidifies to a mass as hard as stone.
Red lead cement is made by mixing red lead with linseed oil to a paste. It is used for cementing the joints of metal pipes.
Lead preparations furnish excellent cements, but have the disadvantage of great weight and a high price. For many purposes a part of the lead combination can be suitably replaced by a substance of less weight, such as whiting, or, still better, burned lime slacked with sufficient water to convert it into a powder.