Warning: My first hot bluing job showed me what quality really means.
I learned from an old timer who still used a proper hot tank in his shop. The whole room would fill with steam, and you had to get the mix just right. We spent a whole afternoon on one barrel, checking the color every few minutes. Now, most folks just grab a cold blue kit from the shelf for a fast touch-up. It gets the job done quick, but the finish never has that same rich, deep black. You can spot a cold blue job from across the room after a year of use. That slow, smelly process taught me to care about how things last, not just how fast they get done. I still have that first barrel I blued, and it looks as good as the day we pulled it out.