Prussian blue is present in some preparations of laundry bluing, such as Mrs. Stewart's Bluing. Instead of the normal bluing, the revolver was given a dull parkerized finish. Fume bluing is another process similar to rust bluing. Rust bluing was developed between hot and cold bluing processes. Finishes include (among others)&colon; paint, varnish, bluing, browning, oil, and wax. Surface finishes for steel strap include&colon; paint, paint and wax, bluing or zinc and wax. Selenium-containing cold bluing solutions work by depositing a coating of copper selenide on the surface. The difference is immersion in boiling water for bluing. Treating with an oiled coating enhances the protection offered by the bluing. Similarly, Prussian blue is the basis for laundry bluing. Among its many uses, Prussian blue gives the blue color to blueprints, bluing, and cyanotypes. Both refer to the same chemical process for providing true gun bluing.