Chemical milling of magnesium metal and magnesium alloys

Claim 2

AN AQUEOUS ACIDIC TREATING BATH FOR CHEMICALLY DIMENSIONING MAGNESIUM ARTICLES COMPRISING BY VOLUME BETWEEN 5 AND 85 PARTS OF PHOSPHORIC ACID, HAVING A CONCENTRATION OF AT LEAST 85 PERCENT H3PO4; BETWEEN 5 AND 25 PARTS OF AN ALIPHATIC POLYHYDRIC ALCOHOL (THE TOTAL OF THE ACID AND ALCOHOL NOT EXCEEDING 100 PARTS); BALANCE WATER, AS NEEDED, TO MAKE 100 PARTS BY VOLUME; AND BETWEEN 1 AND 45 PERCENT BY WEIGHT OF THE COMPOSITION SO MADE OF A NITRATE SALT SELECTED FROM THE CLASS CONSISTING OF THE NITRATES OF AMMONIUM AND ALKALI AND ALKALINE EARTH METALS.

Claim 3

THE METHOD OF SELECTIVELY CHEMICALLY DIMENSIONING A MAGNESIUM ARTICLE CONSISTING OF MASKING OFF THE PORTIONS OF SAID ARTICLE WHICH ARE TO REMAIN UNREDUCED IN SIZE WITH A COATING MATERIAL WHICH IS IMPREVIOUS TO AQUEOUS ACIDIC SOLUTIONS AND IMMERSING THE THUS PARTIALLY COATED ARTICLE IN THE BATH OF CLAIM 1 AT BETWEEN 60* AND 180*F. WHILE MAINTAINING A RELATIVE MOTION BETWEEN SAID BATH AND ARTICLE FOR AT LEAST A PORTION OF THE TIME OF IMMERSION UNTIL THE UNMASKED PORTIONS OF SAID ARTICLE ARE REDUCED TO THE DESIRED DIMENSIONS, REMOVING THE SO TREATED ARTICLE, AND RINSING THE ARTICLE WITH WATER.