SETT FOR PARTIELL EMALJERING AV FOREMAL AV ROSTFRITT STAL

摘要

A method of partially enamelling articles of stainless steel in which areas of the articles are left un-enamelled comprises degreasing at least the areas to be enamelled and pretreating with an adhesion improving treatment prior to covering with enamel, firing the enamel and polishing the enamel-free surfaces. The adhesion improving treatment involves applying a layer of nickel, cobalt or copper then electroplating with an adhesion incurring layer of iron. A mean thickness of an electroplated iron layer in the range of from 5 mu to 20 mu is preferred. The iron layer is improved by picking before enamelling, either electrolytically or chemically. Removal of oxides, scales and intermediate layers from the enamel free areas after firing is performed by pickling in a sulphuric acid and phosphoric acid liquor. Improved removal is achieved by first anodically electrolytically pickling the article, then chemically pickling it and then alternately anodically and cathodically electrolytically pickling the article.