Improvement in galvanizing metal
US 221200 A
Description (OCR text may contain errors)
m STATES PATENT OFFICE.
WILLIAM H. WAHL AND EDWARD Y. ELTONHEAD, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNORS OF ONE-THIRD OF THEIR RIGHT TO CALEB H. HORNE, OF SAME PLACE.
|MPROVEMENT IN GALVANIZING METAL.
Specification forming part of Letters Patent No. 221,200, dated November 4, 1879; application filed To all whom it may concern:
Be it known that we, WILLIAM H. WAHL and EDWARD Y. ELTONHEAD, both of Philadelphia, Pennsylvania, have invented a new and useful Improvement in Galvanizing, of which the following is a specification.
Our invention consists in scaling and clearing iron objects prior to coating the same with zinc or other metals by subjecting the objects to an acidulated aqueous solution of chloride of zinc, as described hereinafter.
In preparing the bath we dissolve chloride of zinc in water and add from five to ten per cent. of mnriatic acid, the solution being afterward concentrated by evaporation until it has become of a sirupy consistency. This concentration is not absolutely essential; but we have found the acidulated chloride to be more active in the performance of its duties, when deprived of a portion of its water, and the action is facilitated by the application of heat.
We may remark here that a cheap way of making this solution is to utilize the precipitated zinc iron alloy of galvanizing baths, which is commonly called dross, by converting it into a chloride of zine, and then dissolving this cheap chloride in water and adding the proper amount of acid. The iron objects are immersed 'in this solution, and are permitted to remain therein until entirely freed from the scale or oxide. This may require from fifteen minutes to two hours, according to the thickness and tenacity of the scale on the surface of the iron.
While the chloride of zinc alone or the acid alonepossesses the property of clearing scale from the surface of iron, wehave found that when combined each ingredient enhances the activity ofthe other, and consequently that the clearing effect is more rapidly accomplished by the acidulated bath than by the chloride