26 



PROCESS TO MAKE VARNISHES. 



who joined the best information and the 

 strongest sense to the most extensive ex- 

 perience, are better deserving the notice 

 of the practical farmer, than whole vol- 

 umes by a mere theorist, whatever may 

 be his rank or acquirements. The advice 

 of Mr. Davis, in the last paragraph can 

 never be attended to without producing 

 corresponding advantages. 



PROCESS TO MAKE VARNISHES. 



Lack varnishes, or lacquers, consist of 

 different resins in a state of solution, of 

 which the most common are mastich, san- 

 darach, lac, benzoin, copal, amber, and 

 asphaltum. The menstrua are either ex- 

 pressed or essential oil, or alcohol. For a 

 varnish of the first kind the common 

 painters' varnish is to be united, by 

 gently boiling it, with some more mas- 

 tich or colophony, and then diluted with 

 a little more oil of turpentine. The lat- 

 ter addition promotes both the glossy ap- 

 pearance and drying of the varnish. Of 

 this sort also is the amber varnish. To 

 make this varnish half a pound of amber 

 is kept over a gentle fire in a covered 

 iron pot, in the lid of which there is a 

 small hole, till it is observed to become 

 soft, and to be melted together into one 

 mass. As soon as this is perceived the 

 vessel is taken from the fire and suffered 

 to cool a little, when a pound of good 

 painters varnish is added to it, and the 

 whole suffered to boil up again over the 

 fire, keeping it continually stirring. Af- 

 ter this, it is again removed from the fire 

 and when it is become somewhat cool, a 

 pound of oil of turpentine is to be grad- 

 ually mixed witli it. Should the varnish 

 when it is cool, happen to be yet too thick, 

 it may be attenuated with more oil of 

 turpentine. This varnish has always a 

 dark brown color, because the amber is 

 previously half burned in the operation; 

 but if it be required of a bright color, 

 amber powder must be dissolved in trans- 

 parent painters' varnish, in Papin's Ma- 

 chine, by a gentle fire. As an instance 

 of the second sort of lac varnishes with 

 etherial oils alone, may be adduced the 

 varnish made with the oil of turpentine. 



For making this, mastich alone is dis- 

 solved iii oil of turpentine by a very 

 gentle,, digesting heat, in close glass ves- 

 sels. This is the varnish used for the 



modern transparencies employed as win- 

 dow-blinds, fire screens, and for other pur- 

 poses. These are commonly prints, col- 

 ored on both sides, and afterwards coated 

 with this varnish on those parts that are 

 intended to be transparent. Sometimes 

 fine thin calico, or Irish linen, is used 

 for this purpose, but it requires to be 

 primed with a solution of isinglass be- 

 fore the color is laid on, copal may be dis- 

 solved in genuine Chio turpentine by ad- 

 ding it in powder to the turpentine pre- 

 viously melted, and stirring till the whole 

 is fused. Oil of turpentine may then be 

 added to dilute it sufficiently. A varnish 

 of the consistence of thin turpentine, is 

 obtained by the digestion of one part of 

 elastic gum, or caoutchouc, cut into small 

 pieces, in thirty-two parts of naphtha. 

 Previously to its being used however, it 

 must be passed through a linen cloth in 

 order that undissolved parts may be left 

 behind. The third sort of varnishes con- 

 sist of the spirit varnishes. The most 

 solid resins by themselves produce brittle 

 varnishes; therefore something of a softer 

 substance, must always be mixed with 

 them, whereby this brittleness is dimin- 

 ished. 



For this purpose Elemi, Turpentine, 

 or balsam of Capaiva, are employed in 

 proper proportions. For the solution of 

 these bodies the strongest alcohol ought 

 to be used. In conformity to these rules 

 a fine colored varnish may be obtained by 

 dissolving eight ounces 'of gum Sandar- 

 ach, and two ounces of Venice turpen- 

 tine in thirty-two ounces of alcohol by a 

 gentle heat. Five ounces of shell-lac and 

 one of turpentine dissolved in thirty-two 

 ounces of alcohol by a very gentle heat 

 give a harder varnish but of a reddish cast. 

 To these the solution of copal is undoubt- 

 edly preferable in many respects. This is 

 effected by triturating an ounce of pow- 

 dered gum copal, which has been well 

 dried by a gentle heat, with a drachm of 

 camphor, and while these are mixing to- 

 gether, adding by degrees, four ounces of 

 the strongest alcohol without any diges- 

 tion. Between this and the gold varnish 

 there is only this difference, that some 

 substances that communicate a yellow 

 tinge, are to be added to the latter. Take 

 two ounces of shell-lac, of annatta, and 

 turmeric, of each one ounce, and thirty 



