Odd, I've always found it to have a "stink" (copper sulfate) like nothing else. The only way I got decent results, even with superior metal prep, was to heat the object slightly, apply from another container, and use the cold water to arrest the process, steel wool and a pleasant smelling oil afterwards. (G96 for example).The cold blue doesn’t have much of an odor. The rust and blue remover has a little acidic odor. I did the bluing in small sections as you have only 60 seconds before you must neutralize the process by running it under cold water, or it will mess it up and you have to strip it all off and start again. It took 3 coats with polishing in between coats with steel wool to even out the finish.