698 Transactions of the American Institute. 



There is no advantage in adding more water-glass than is absolutely 

 necessary to fix the colors. If too much is used, the surface becomes 

 bright, which is also the case if too much lime is in the water. 

 Those briglit places turn, in the course of a few days, into a white 

 film, which, however will disappear in the course of time, or must be 

 removed with a sponge and clean water. The safest way to insure 

 success is to begin the fixing with a weak solution, and repeat it three 

 or four times, rather than to use a strong solution at once. 



The colors and pigments. to be used are as follows: Zinc white; 

 permanent wliite (artificial sulphate of barytes) ; dark yellow, burnt, 

 and brown ochre ; terra de Sienna, raw and burnt ; cadmium and 

 chrome yellow ; red chrome, green chrome ; blue and green ultra- 

 marine ; oxyd of iron in red, brown, and crimson ; burnt umber ; 

 mineral and lampblack. No vegetable color is admissible. Yermil- 

 lion, cobalt, and light ochre ought to be avoided also. 



For large surface, for walls where expense is a consideration, lime 

 and chalk (whiting) may be used, only those latter do not cover well ; 

 a little addition of zinc white will balance that defect and produce a 

 good "body.". It should also be borne in mind that water-glass is 

 antagonistic to oil-paint ; if any oil-painting is in proximitj' to water- 

 glass painting, or upon a wall to be fixed, the oil-paint ought to be 

 covered with paper before fixing with water-glass, otherwise the oil- 

 paint will suffer. Woodwork when new, where a smooth and even 

 surface is not required, and where the smell of paint is too obnoxious, 

 may be coated with w^ater-glass. In that case it is reconnnended to 

 " bind " the colors with weak size, and apply the water-glass afterward 

 with a brush. Woodwork is also protected against fire by the simple 

 application of two or three coats of pure water-glass, without any 

 pigment. The wood so treated becomes darker. 



One more observation as a guide to the operator is this ; all the 

 •colors become a little darker under the fixing process, but in the 

 course of a few days they regain their original tone. Certain colors, 

 such as oxyd of iron, artificial white barytes, and some of the ochres, 

 contain sometimes smaller or larger portions of sulphuric acid. 

 These colors must therefore be washed M'ith plenty of pure water 

 before using them for painting. 



The reading of the last item drew forth considerable discussion, in 

 the course of which Dr. Vanderweyde stated that coating a wall with 

 size, and washing it with alum water, by which a sort of a leather is 

 formed, wliich can be washed without injury. This is a very good 

 surface for fresco painting. 



