Brittle Varnish

¶ Brittleness of Varnish. One of the greatest problems of the varnish maker has always been to produce varnish which will dry hard, rub smoothly and clean and be sufficiently elastic, in other words,, to secure these qualities without making the varnish brittle. Brittleness is a matter of degree. Some are more brittle than others. Interior short-oil varnishes and rubbing varnishes necessarily are more brittle as a class than exterior, long-oil varnishes which must be very elastic to withstand exterior exposure.

¶ Excessive brittleness of varnish is an inherent defect which is due to an excess of drier, lack of oil, adulterated gums or improper cooking. When a varnish crumbles and powders white under friction from the finger nail, when it scratches white easily that varnish is of poor qualify. Brittle varnish has no value except, perhaps, as a temporary coating on barrels, etc. It should not be used on surfaces as under coats on the theory that it will be protected by the good quality, elastic finishing coats. The brittle varnish will then rob the finishing coats of its tough, elastic character upon which it is dependent for durability.

Next Page: Livering Varnish.