Noticed a small spec of finish on my rear IDOT sight was worn out. It actually rusted from being in transit from the USPS (Cold temp/condensation.). I used break free CLP and a toothbrush and got rid of it. What is the best way to put some kind of coating on the metal to protect it from rust? Would bluing solution be okay? I plan to remove the rear sight and apply it. The only way I actually noticed it was by photographing it. So it's not really that big of a deal if the color doesn't perfectly match.

I'm just thinking it came off because of how tight the M&P Dovetails are. I didn't notice it when the slide was melonited black.
Can somebody recommended a good way to touch up the bare metal and prevent rusting on the rear sight. I don't care if the black doesn't perfectly match. I was considering using a small bit of bluing and reinstalling the sight once it's treated

Would this work alright?

Birchwood Casey gun blue pen or Birchwood Casey super black touch up pen

Duplicate

You should be vary careful with cold blues.
The acid in the chemical will actually CAUSE rust unless the metal is very thoroughly rinsed and oiled after use.

Another problem is that cold blues will leave a discolored blotch in the original blued finish.
For this reason, try to keep the cold blue limited to only the spot it's needed.

To increase the quality of the cold bluing, you need to do a very thorough job of degreasing the area.
Even alcohol and a toothbrush will do a good job.
After cleaning the area, warm it up with a hair dryer to increase the cold bluing ability to color the metal.
(Note: hair dryer, not a torch or heat gun).

Last, note that cold blue is not at all durable and can often be wiped off by a light rub with a finger.
It's better than nothing to color worn spots, but don't expect too much.  No cold blue can match a factory hot salts blue job for color or durability.

That is really going to tough to touch up, the durability of any cold blue is weak.  If it bugs you that much, pull the sight, prep it and use a ceracoat or duracoat paint.

The Birchwood pens are a cheap and easy fix.



 

I actually drifted the sight out, and gave it a good scrubbing/oil. Ended up reinstalling it as is.

I did some reading and it appears Ameriglos rust easy. I noticed there was rust in places that had no finish wear at all. I'll probably be replacing it with a rear sight that is Melonited. Front sight seemed to have no issues.

Thanks though.

Your gun needs a better oil coat to protect it.

I still use Break Free CLP since I have gallon cans.
Take the whole gun down to every bit part.
Soak all the piece in CLP for about 24 hours.
Take them out and let them drain on multiple layers of paper towel for 24 hours.
Wipe them down one by one with minimal finger contact unless you have nitrile gloves on.
Put it back together wearing nitrile gloves and wipe down exposed surfaces one more time.

If it bothers you (which it obviously does or you wouldn't be posting about it) take it off and touch it up with "Super Blue".

1. Clean with brake cleaner or alcohol to remove any oil.
2. Apply cold blue with cotton ball or cue tip.
3. Let sit for 30-40 seconds, then rinse off with cold water.
4. Blend with 0000 steel wool.
5. Repeat until the bluing is dark enough to match.
6. Remove all solution and soak in oil.

I used to lightly restore surplus military rifles and have had great luck doing touch-ups with Super Blue.

A black permanent marker is often just as effective as a cold blue touch up.

EM-nu.  Just a simple black lacquer dull touch up. Cheap and works well.