| 摘要 |
The invention relates to an aqueous stripper free of wetting agents and emulsifiers, intended for use with special steels. Said stripper, on a basis of sulfuric acid or phosphoric acid and hydrofluoric acid, contains (in each case in relation to 100 percent by weight of substance): between 1.5 and 16 weight percent sulfuric acid or between 2.0 and 30 weight percent phosphoric acid, as well as between 0.5 and 14 weight percent hydrofluoric acid and between 0.5 and 15.5 weight percent acid-soluble aromatic nitro compounds. No iron(III) compounds are added to said stripper. Only in the initial phase an oxidizing agent which oxidizes iron(II) to iron(III) may be added. As acid-soluble aromatic nitro compound m-nitrobenzol sulfonate and/or 3-nitrophthalate are especially advantageous. The stripper provided for by the invention can be used in a stripping bath and, if between 2.5 and 5.5 weight percent magnesium and/or magnesium compound (calculated as Mg) are added, can also be applied by spraying or with a brush.
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