Читать книгу Henley's Formulas, Recipes and Processes (Applied Chemistry) - Various - Страница 682

—Cast-brass work, when it presents numerous and deep sand holes, should be well dipped into the dipping acid before being polished, in order thoroughly to clean these objectionable cavities; and the polishing should be pushed to an extent sufficient to obliterate the smaller sand holes, if possible, as this class of work looks very unsightly, when plated and finished, if pitted all over with minute hollows. The larger holes cannot, without considerable labor, be obliterated; indeed, it not infrequently happens that in endeavoring to work out such cavities they become enlarged, as they often extend deep into the body of the metal. An experienced hand knows how far he dare go in polishing work of this awkward character.