Touching Up Blue - Questions

[LBussy]

Greetings Smiths!

I was wondering if I might interrupt to ask what surely is a trivial question or two about touch-ups. I know this might be seen as below the signal to noise ratio here so I appreciate any advice. I have a blued Ruger MKIII that I picked up used. There are a couple scratches on the frame, and some dings from assembly/takedown around the mainspring housing.

First, what's the best cold blue/touch-up to use for this?

Second, are there any tips you might share in applying it that will help it look less like I did the touch-up, and more like you did?

Thanks in advance for any tips.

[arquebus357]

I favor Brownell's Oxpho- Blue for touch up work. For Aluminum (some sights) I like the Birchwood Casey Aluminum Black product. Aluminum Black works very good if you are patient and rub, rub, run with a Q-tip. Clean parts with alcohol or something before applying either product.

Just yesterday I used Oxpho-Blue to touch up a S&W revolver sight (steel) that suffered some cosmetic damage from the replacement of the sight blade. (by me)

[LBussy]

Thanks arquebus357.

When you say "rub, rub, rub" do you mean when applying the product, or after to buff it? Any need to mask the area?

[arquebus357]

Sorry... I meant while applying the product. When I first got the Aluminum-Black I experimented on a X-acto knife handle by rubbing a spot with a q-tip. Now a couple of years later, that spot is still there. I did not find it necessary to mask anything I ever applied it to. ( mostly Ruger revolver rear sights and sections of picatinny rail).

I have seen negative comments for Aluminum-Black and I think peoples problem with it is that they expect it to work instantly like the cold bluing products do on steel. It does not !!!

[T. O'Heir]

Which brand of cold bluing doesn't make much difference. Outer's works as well as any brand. Used it to cover a spot on my GP that got eaten away by the vinegar in my leather dye. The GP's finish is not bluing. Some kind of coating. Metal isn't polished at all. Dunno if a Mk III is or not.
The trick is to completely clean with a degreasant(mineral spirits) and use a lint free cloth. A light touch with some 0000 steel wool first.

[LBussy]

Gotcha, thank you both.

[tangolima]

I use blue mountain.

Read and understand the instructions thoroughly. Practice on scraps till you are proficient.

-TL

Sent from my SM-G930T using Tapatalk

[JohnKSa]

I've not found anything easier than OxphoBlue for touchup. There's no need to do a rinse on the part after each application like some cold blues require. The parts I've blued/touched up with it seem to be about as rust resistant as a typical blued part.

The only thing I've noticed that I dislike about it is that some rust preventives will change the color to a dull brown from the normal black color. Doesn't have any effect on the rust resistance that I can tell--it's just not as pretty.

[Unclenick]

LBussy,

I'll disagree with T. O'Heir. I found significant differences in the cold blue chemistries. If you look at the ingredients, those using nitric acid, like 44-40, were generally darkest and bluest, while those using phosphoric acid, like Oxpho-blue and Van's are more like a dark charcoal gray. However, the nitric acid-based ones are much more prone to after-rust appearing. I recommend post-application rinsing and acid-neutralizing for them all, followed by a water-displacing oil application, but the phosphoric acid-based ones do leave a thin metal conversion layer of colored phosphatized steel, which actually holds the oil and protects from rust to some degree. So I consider them better from a utility standpoint.

None of these things perfectly matches a rust bluing job or a hot bluing job (what's on your gun), so don't expect that.

Regarding aluminum black, I had occasion to buy a gallon of this material from an industrial supplier once for coloring some bare aluminum heat sinks. If you simply soak aluminum in them, you end up with bare spots and pinholes that I believe are caused by bubbles forming. It isn't pretty. But the scrubbing method works. I diluted it with 1 part solution to 3 parts water and submerged the aluminum in it and continuously scrubbed it all around with a retired toothbrush until it was uniformly black. This worked very well. Since alkaline materials etch aluminum, I did not acid-neutralize it directly, but I did wash it with dishwashing liquid in water, followed by a thorough hot water rinse.

[LBussy]

Since these are scratches more than rub marks, I believe the phosphoric acid-based blue may be my best bet. These won't show much so the lighter color is not as important, but protecting them from rust is a big focus.

I appreciate the detailed descriptions. I may pick up both types to have around (along with the aluminum black) just in case.

[Scorch]

First, what's the best cold blue/touch-up to use for this

Ask 100 gunsmiths and you will get a couple dozen answers.

For me, for screw heads and smallish scratches, Van's Gun Blue is my choice because it gets the steel nice and dark and doesn't stain the surrounding blue, and leaves no residue to clean up.

For larger worn areas, Oxpho-Blue gets the nod because it gets darker and looks more like bluing that other cold blues. It leaves a residue behind that can be hard to get out of screw heads or markings. It will also stain bluing around the area you are touching up, so it is obvious to the experienced eye that the area has been touched up.

Degrease before, and oil after.

[LBussy]

Scorch, I don't mind getting 100 opinions. I may get to the shop and they don't have what it was I was going to buy so I end up going with something someone else recommended. Your experiences are really what makes the difference, more so than brands.

What I'm surprised to see is nobody warned me away from a particular brand.

[tobnpr]

Another vote for Oxpho.
I use gray Scotchbrite in between coats until desired color is achieved. The degreasing before and oiling after as mentioned is important.

[arquebus357]

Using oxpho-blue on large items like frames, barrels etc. I apply using 0000 steel wool. First you need to rinse the steel wool with acetone, naptha or something to get rid of the oil thst steel wool carries to prevent it from rusting away.

I find that this is the only way to get an even effect.

[Unclenick]

LBussy,

I'll warn you away from one particular one. Outers has a hydrochloric acid-based blue that initiated rusting very easily in my tests. The problem with anything chlorinated is the chlorine reacts with iron to form ferric chloride and then likes to trade off which iron atoms it bonds to for the ferric part and can gradually tunnel into steel. If it gets anywhere that the steel is stressed, such a where threads are tight, it can lead to cracking. I think this is why Naval Jelly went from using hydrochloric acid, as it did when I was young, to phosphoric acid (that, and the fact phosphoric leaves a thin phosphate layer that mitigates corrosion for a short time).

I can't say I'd noticed the residue issue with Oxpho-blue or that it darkened particularly better than Van's, but there are two versions of it. One is a cream and the other a liquid. I use the latter. Whatever thickens the cream might be part of the residue mentioned.

BTW, another good application method I've found, in addition to scrubbing with a toothbrush and that works with iron and aluminum blacks alike, is to dilute the solution with 3 parts water and put it in a cup that you suspend or float in an ultrasonic cleaner. The ultrasonic scrubbing action seems to accomplish the same thing the brush does, plus a lot of ultrasonic cleaners have heaters so you can make it all happen faster. I would use this method only when coloring a whole part, like a screw or a hammer or a pin, and not try to go part way up a barrel with it, as a color line may well become visible where the submersion stops.

[LBussy]

Thanks for the tip about the Outer's.

Naval Jelly has always been phosphoric acid based as long back as I remember, it musta been a couple minutes back that it was hydrochloric acid based. It would definitely be a less desirable way to go, but I imagine it worked pretty fast.

I never would have thought about using an ultrasonic cleaner but that's something I'll tuck away in the gray matter.

[Unclenick]

I'm pretty sure it had hydrochloric acid in the 60's. I do remember rinsing it off a rusty spot on a fender and having that develop fresh surface rust as fast as the rinse dried. But when memories are that old, the brain sometimes pulls substitutions. It's possible I bought an off-brand from K-Mart or some such thing back then, and am remembering that, instead. So, perhaps I shouldn't mention Naval Jelly by name.

[mycanoe44]

(arquebus357 - Using oxpho-blue on large items like frames, barrels etc. I apply using 0000 steel wool. First you need to rinse the steel wool with acetone, naptha or something to get rid of the oil thst steel wool carries to prevent it from rusting away.
I find that this is the only way to get an even effect.)

This, plus I heat the part up with a heat gun also. I put some Oxpho in the cap and dip a small piece of degreased 0000 steel wool in it and work it into the scratch or small wear area until it gets as dark as you want it. Make sure the part is fully degreased also. I've found applying it this way to a heated part so it flashes off between coats, works way better than doing it cold and blends much better. YMMV

[dakota.potts]

I prefer Oxpho-Blue as well.

I did a short (~2 minute) video on the process when I was documenting some of the stuff I did in gunsmith school. It may help if you have questions about how the paste is actually applied.

https://youtu.be/KC_1syhOmAA

[LBussy]

Originally Posted by dakota.potts

I did a short (~2 minute) video on the process when I was documenting some of the stuff I did in gunsmith school.

Thanks I'll check that out.