144 Laboratory Arts 



well rubbed in, finally the remainder wiped off, and the work 

 allowed to stand a while. 



" Red oil " is frequently used by professional French 

 polishers, and this appears to be a mixture of raw linseed 

 oil, spirit, bichromate of potash or some similar oxidizing 

 substance. The object is the same as that above to stop 

 up the pores (if only temporarily), and so allow the polish 

 to remain on the surface. 



It will save time if soft woods are painted at this stage 

 with shellac varnish and a little raw linseed oil. This mixture 

 penetrates a little, but quickly dries, and as the spirit 

 evaporates, a layer of shellac remains which prevents the 

 entry of the polish that is to follow. On drying completely, 

 the whole surface is glass-papered down again, and a 

 second painted coat given, and glass-papered as before when 

 hard. The surface should then be hard and perfectly smooth. 

 Hard woods may receive a similar coat, but this is really not 

 necessary, and very little time is saved by such treatment, as 

 the subsequent glass-papering removes practically the whole 

 coat. 



Having now secured "a hard and smooth surface, the 

 actual polishing commences. The object of French polishing 

 is to put upon the wood a thin film of shellac, and to burnish 

 this by pressure while it is in that peculiar state of semi- 

 solidity or pastiness which the shellac exhibits during the 

 instant immediately preceding the total evaporation of the 

 solvent. The film of shellac applied is, however, so thin that 

 the condition approaches and passes very rapidly, and in the 

 " nursing," of this condition to cover the whole surface simul- 

 taneously, much of the polisher's skill is centred. 



The method of securing this film is as follows : In the 

 centre of a linen cloth some ten inches square is placed a pad 

 of cotton-wool, about nine cubic inches in size before com- 

 pression. This pad is saturated with a solution of shellac 

 in methylated spirit (or, better, in rectified spirit), the linen 

 cloth is wrapped round it so as to enclose it totally and 

 allow no single fibre to stray, and by holding it in the right 

 hand and patting it against the palm of the left hand, this is 



