This thread is to show a step by step guide on how to rust blue some steel. It is a very forgiving process, but it is time intensive, so there is no instant gratification like the hot blue. If you persevere though, you will get the excellent results and a durable blue job that is rare to find nowadays on our mass produced firearms.
Step one. Get your metal prepped by sanding down with progressively finer grades of sandpaper. The finest grade you would probably want to use is about 350-400 grit. Anything finer would be a waste of time, as the acid will etch your finely polished surface and bring a lot of that hard work back down to about a 350 grit polish. Hand polish your parts. Do not use the belt sander, ok?
I would highly recommend using a sanding block for flats to keep the corners sharp. The direction of the sanding should be in the same direction, but it is not absolutely necessary to do so. TRY to get everything going in the same direction. I intentionally sanded in both directions to show that this is not critical to get good results, but MAY show up in the finish later.
Just like painting, prep work makes the final result look fair, good, or great! The rusting process will eliminate most of your small imperfections in your sanding job, so don't worry too much if it doesn't shine like a mirror. Just get it sanded down as best as you can an eliminate any pitting or deep scratches, as these can be spotted when the job is finished
For this exercise I will be using a small jewelers hammer that I picked up at a local pawn shop for 1.00
Always start your first project on something that is cheap so you can gain confidence and get a feel for how it works. Long story short, don't get the Winchester 1873 family heirloom out of the safe yet!
You will want to clean all traces of oil/wax/grease off of the part. The only problem I've ever had rust bluing a part was a rifle treated with silicone. That stuff is a nightmare to remove!
I use regular dishwasher detergent to remove any oil from my parts. It has a high alkalinity and is made to be aggressive on grease. Rinse with plenty of hot water. Try to handle the part with bare hands as little as possible. Using gloves is recommended, but not absolutely necessary. (Did I mention that this process is extremely forgiving?
To be continued...stand by...