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XLIX. On the Preparaiion and Use of Copal Varnhh o? a 

 Fthicle preferable to Oil for the Purposes of the Painter. 

 Bjj Mr. Cornelius Varley. 



To Mr. Tillocln 



Sir, — J. BEGj through the mediiiin of your valuable Magazine, 

 to lay before artists the iriethod of preparing pure copal varnish 

 in spirits of turpentine *, witliout heat. It is quite transparent, 

 colourless, durable, protects the colours, and does not change 

 in the least. Tiiis is the purest material I have yet found, and 

 is the only vehicle I use to paint with. 



Take the cleanest and whitest lumps df copal ; beat them 

 small, and pick out all tlie impurities. Pound them to a fine 

 mass in a glass or Wedgwood's mortar; then pour in colourless 

 . spirits of turpentine to about one-third higher tiian the copal, and 

 work up tl'.e whole quite fine ; in half an hour work it up again 

 till fine (if left too long, it will get so tough as not to be rubbed 

 up again) ; and in an hour work it up again, and once or twice 

 more in tiie course of the day. The next morning it may be 

 poured off into a bottle lor use; but as it is thicker or thinner ac- 

 cording to the c|uantitv of turpentine and the heat of the weather, 

 it should be tried as follows, before bottling it up : Dip a palette- 

 knife in, and tlrv it by the fire as quick as you can without burn- 

 ing it; and if, when cold, it is found to have left on the knife a 

 fair coat of varnish, it is strong enough : otherwise, work it up 

 ao^ain, and let it stand some time longer. After taking off this 

 first supply, pour on a fresh quantity of turpentine, and rub it up 

 several times during two or three days; — try it by the palette- 

 knife as before ; and when strong enough, pour the liquid off into 

 tlie same bottle with the first. A third (juantity of spirits might 

 be added, wliich would make the remaining copal appear as dry 

 as crumb of bread ; but a much longer time than laefore would 

 be required for the solution. 



To paint with this varnish, use powder colours groimd quite 

 .fine ; or else grind them in spirits of turpentine, and add as much 

 of the varnish as will bind them well. Keep them in bottles, 

 and mix your tints in saucers for use; and as they thicken by 



ing fires in ships ; but as the idea had already been anticipated in our xxist, 

 vol. p. 97. to which our readers can turn, it was unnoccssary to insert them 

 here. He also s«j;tcests that ships might be rendered -more buoyant by 

 making them uir-tighl, and forcinj; in air by means of an .Vn--punip, which 

 would elevate them to a hiffher level in the water, and consequently might 

 Bometimes save them when they have got upon a bank. 



• The common spirits of tuii)entine seems to dissolve copal best ; but 

 when that cannot be had colourless, 1 use the rectified spirits. 



Vol. 51. No, 240. /Ipril 1818. T drying, 



