I'm putting together an M16 clone and decided to use a carrier I already had, A PSA premium (Toolcraft) with the laser engraved emblem. I'm not worried about building original with all Colt parts but I also didn't want a PSA logo on the carrier either. Anyway, on to the point.

I decided to sand off the PSA logo and cold blue the sanded area. Anyone who has used Birchwood super blue knows it does not turn out black, it's a dark blue smooth finish. I wanted to match the original park/ phosphate finish.
First I sanded the steel smooth and blued the area as usual. I got the idea to mix salt into the bluing to see what would happen? I know from past experience that bluing will cause steel to rust if left unoiled. I also knew that salt causes steel to rust. I also knew that the rust blued layer would form a darker and rougher finish than cold bluing alone. Thus, my red neck chemistry experiment was under way.

I took a spoon full of table salt and ground it up into a fine powder. I mixed a couple drops of bluing into the salt to make a wet paste. I applied the paste over the blued area and it immediately turned rust color. I let the paste set on the area for about 30 minutes, it turned into a hard orange crust. I then added a drop of water and mixed it around in the paste and let it sit for a few more minutes to rust some more. The salt caused the steel to form a blacker and rougher finish than cold bluing alone.
The results after wiping off the area and adding some oil are identical to the original phosphate .  If anyone is looking to match a phosphate finish this is a simple way and all you need is bluing and table salt.

This is a tech forum.  Non-tech comments removed - Eric802

DIY for the MFkn win!

Thank you! Will definitely be helpful in the future.

Good knowledge to have,Thanks

Very cool!