Formula No.1 Laundry Sour (see) at pH 5.0 Then add Ammonium Bifluoride 0.5 lb per 100 lb cloth. Heat to 140-180'F. Rinse well at pH 5.0 Souring only to pH 5.0 is usually without effect in removing iron stains. After souring to pH 5.0, it is necessary to add dilute stock solution equivalent to about 0.5 pound of ammonium bifluoride for each 100 pounds of cloth. It is usually advisable to carry out stain removal at 140-180'F. The excess ammonium bifluoride solution should be rinsed out at least to a pH of 5.0. If the soluble, colorless iron salts are allowed to remain in the cloth, the iron stains will show up again the next time the cloth is washed in alkaline solution. American Institute of Iron stains from the following sources may be successfully removed. As above: 1. Prussian Blue 2. Iron from greases 3. Iron inks 4. Rust 5. Cosmetics (lipstick, rouge) 6. Mud 7. Pigments from oil paints Copper stains from verdigris are removed in a manner similar to iron stain removal. Spotting operatio
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