just bought some for cheap to try out. any comments or tips for working with this stuff.

I use both 44/40 and oxpho blue. Just make sure you wash the residual salts off and coat with gun oil to prevent rust.

 a good surface prep, cleaning first with a ( CLEAN ) brush and hot soapy water, then a good lengthy rinse then dry with a clean ( no lint ) cloth really helps the blueing take hold...also wear CLEAN, tightly fitting rubber gloves to keep finger oils off of your project.  Even when your hands are freshly washed and dried they still have contaminants on them.

 I also tend to rinse the blueing off with clean, cold water once it has sat for a few seconds ( 44/40  reaches color VERY quickly ) and then I clean the surface again as described above and do another coat. You can do this as many times as you desire but I rarely do it more than twice.  After my last cold rinse I DO NOT wipe the project piece off I simply rinse the piece with WD40 to chase off the water...and let it sit for a day.  This seems to "cure" the finish nicely.  After that a light rubdown treatment of nice gun oil soaked into a vey soft cloth really brings out the finish.