CASEIN PAINTS. 47 



with carbonic acid gas before use, and must therefore be 

 packed in airtight tins. These paints can be made in a 

 variety of colours, and in the form of a thick pap, which is 

 diluted with water for use. They are prepared by intimately 

 mixing 200 parts by weight of casein in a pulverising 

 machine with 40 parts by weight of powdered and sifted 

 slaked lime, the whole being stirred to a thick pap with 

 some body colour that has been mixed with water. Finally, 

 the paint is put through a mill and packed in airtight tins. 

 The most suitable pigments for this purpose are : 



For White. Zinc- white, lithopone, blanc fixe, heavy spar. 



,, Yellow. Ochre, Indian yellow, Naples yellow. 



,, Brown. Any brown earth pigment. 



,, Black. Ivory black, vine black, lampblack. 



,, Red. Red lead, colcothar, Indian red, madder red. 



,, Blue. Ultramarine, cobalt blue, smalt. 



,, Green. Green earth, cobalt green, chromic oxide green,' etc. 



COLD-WATER PAINT IN POWDER FORM. 

 In making this class of paint the proportions must be 

 selected in such a manner that the mixture shall contain 

 80 parts of dry casein to every 2| parts of dry slaked lime (or 

 caustic soda or potash). Useful results can be obtained from 

 the following recipes : 



45 parts by weight of powdered casein. 

 20 ,, of powdered slaked lime. 

 150 of kaolin. 

 300 ,, of levigated chalk. 

 5 to 20 ,, of pigment, according to the colour desired. 



For a stone-coloured paint, the following proportions are 



suitable : 



100 parts of above paint mass. 



3 ,, of light or dark French ochre. 

 2 ,, of chrome yellow. 

 1 ,, of Cassel brown ; 



or any of the pigments mentioned below, together or separ- 

 ately : 



