Paints, Stains, Varnishes 141 



Water stains, however, are more dilute, they go on evenly, 

 and one does no damage by moving over the same spot twice. 

 They dry very little darker than they appear when applied, 

 and subsequent varnishing usually restores the lost brightness. 

 They have the objections that they " fetch up the grain " (i.e. 

 roughen the wood somewhat) and take longer to dry, but the 

 certainty with which they may be used is more than reparation 

 for these disadvantages. 



Varnishes. One or two only need be mentioned. 



1. Shellac varnish. This is the principal one used for the 

 preservation of laboratory woodwork apart from fixtures. It 

 is made by soaking flake shellac in methylated spirit till soft, 

 gently heating and allowing to stand after a good shaking. If 

 a powder settles, more spirit is added, until a clear liquid is 

 produced. This is suitable for the varnishing of linen strips, 

 joints mended by cements, mirror backs and delicate apparatus 

 of that kind, for insulating coils of wire, and for lacquering 

 brass. For mending and cementing, however, a much stronger 

 solution is required practically a saturated solution being the 

 best. This is made by placing i Ib. of shellac in a jar, cover- 

 ing with methylated spirit and allowing to stand for several 

 days, with frequent shaking. The liquid so produced may be 

 used for painting on coils of wire for insulating purposes, and 

 may be coloured black for negative leads by the addition of 

 lampblack, or red, for positive leads, by vermilion. 



It is very serviceable for varnishing wooden " patterns," 

 models, and wooden stands and appliances in general ; indeed, 

 there is no more useful laboratory preparation than this. 



2. Sealing-wax varnish. This is made by dissolving the 

 best sealing-wax in methylated spirit, and if not sufficiently 

 brilliant, adding a little vermilion and shellac varnish to the 

 solution. It is used for painting corks, iron magnets, insulated 

 coils, and various electrical apparatus. 



3. Silicate varnish, white paper varnish, dark oak varnish, 

 had each better be purchased as required. The former is 

 useful for painting bright articles (nickel, gunmetal, etc.), 

 which it preserves, from atmospheric effects, and the uses of 

 the others have already been described. 



