Thread: Cold Bluing.

Just picked up an older shotgun that has gone a bit rusty. 80% of the bluing is gone. I'm going to give it a tidy up and looking to use some cold bluing to restore the steel work.

I'm sure there's plenty of experience on here to help with this.
What's a good product to use and any tips on how to do it.

Theres far more exerianced guys here than me but ill share what I figured out after doing a few of my own jobs. First Id start off with a birchwood kit. Its got nearly everything in it to get you started without to much mucking around. The only thing extra I get is gloves, makeup remover pads, a roll of handy towel and a tube of bluing paste. Just follow the instructions in the kit but I use the makeup remover pads to apply the blue. You need to keep rinsing the job between coats for this I have 2 jugs on the go boiling water and i rinse with boiling water and dry with the handy towel. Keep going untill you get it how you would like it then I finish of with a coat of paste. If your anything like me it will be a bit streaky when you have a close look and Ive found for me the paste gets rid of the streakyness. Then i just put a coat of light engine oil all over it and sit it in a warm spot for a day or so. My first couple of trys turned out like shit but this method was a great improvement.

Meticulous surface prep - any areas that are different, corroded, old blue etc will take the cold blue in a different way. There are different types of cold blue chemicals and some will work where others dont... Worth keeping in the back of the mind on your 15th attempt at coating a stubborn spot.

I 've used the Birchwood super blue with good results. Follow the instruction's on the bottle. Like NO.3 said Prep is the key and a good degreaser to get all those years of oil. I found warming up the steel seems to help the process to (only warm to the touch)

I've also tried using different ways of degreasing acetone iso meths wax and grease remover etc, but none really worked that well. the degreaser in the kit works the best...

Used the Birchwood Casey 'superblue' (I think) to do some gun bits I'd made that were 4140 and 4340. Those bits went 'black' - and are still black ten years later.
I've also used it on mild steel, and that took okay, but is starting to look 'antique' - but you gotta look to see it.
I wasn't expecting that - I did my 'Sharps' in the 1970's and that went 'steel grey'. Can't remember what steel's were in that thing other than 'Brake Die' I used for the action frame - and probably other bits.

the remington 600 I did went steel grey for a start but just kept putting more coats on Its the best one I've done so far.

I probably ran out of patience, or more likely - Birchwood Casey.

Have restored alot of rifles over the years and experimented with lots of the cold blue products. I agree 100% with comments above - the best results by far are from Birchwood Casey Super Blue.

My method is very much my own! - something I've developed over years. Clean thoroughly the surfaces to be blued - 2-3 washes with detergent to strip residual oils, then dry metalwork. Then I take a well worn green plastic kitchen pot scrub. NOT new - a worn one as we do not want to abrade off the blue while being applied. Then touch soft green scrubber into blueing liquid and begin to gently work it onto - and into - metal surfaces. Often surface pores will retain oils and cause blueing agents to bleed, seperate, become patchy, not covering everything. I keep gently working blue into and around all metal work, increasing strokes along barrel length for evenness. This works blueing compound into surface. I keep gently working it on - no abrasion - until all done. Then instead of leaving it 1-2 minutes as some products suggest, I'll leave it 10 - then look at it. By this time its usually a deep blue/black and because its been gently worked in over 5-10 minutes its usually 100% even. Then its time to clean metalwork again and apply oils. Heavy coating of CRC is good - its an antirust and the blueing is a form of rust - or so they say.

Results with this quirky personal method plus Birchwood Casey Superblue have been excellent. Deep blueing, as good as new, and it certainly isn't wearing off!. Just remember not to use a new green scrubber. The old one works product in well, but avoids harming new surface.

Other thing that might have helped with my 'bits' - is I oil them with boiled linseed oil. It's an air drying oil and used to be the 'oil of choice' for paint ............. way back.

I use it on most anything that'll rust - knife blades and what have you. Raw works too, just takes longer to 'dry off'.
It will wear off with use - just reapply.

That's a good method Mudgripz outlined - probably won't find it next time I go looking .........

A far better method would be to rust blue the thing.
Cold blue is effectively paint, proper bluing actually changes the surface structure of the steel.

Still will rust like shit if you leave it untreated??

The "Search Forums" box will find you many posts about cold bluing and slow rust bluing

Now I'm not a chemist by training - but the cold blueing Birchwood Casey product process is not painting on blue. Here's the blurb:

"The Birchwood Casey super blue for deep, blue-black finish penetrates hard steel instantly. The Casey super blue is double strength bluing solution designed for bluing highly polished steel parts and hardened steels containing nickel and chrome alloys."

Its visibly a chemical process as you work it across gun metal inch by inch - apparently a controlled oxidation of the metals similar to rust. Some earlier products were less effective but this last one very good. Does it work - and last - yes. Birchwood Casey Superblue an effective blue process from my experiences. I can't ask for more than that.. Give some a try Akaroa - or sometime I'll come over to Aka and do a rifle for you..

Originally Posted by mudgripz

Now I'm not a chemist by training - but the cold blueing Birchwood Casey product process is not painting on blue. Here's the blurb:

"The Birchwood Casey super blue for deep, blue-black finish penetrates hard steel instantly. The Casey super blue is double strength bluing solution designed for bluing highly polished steel parts and hardened steels containing nickel and chrome alloys."

Its visibly a chemical process as you work it across gun metal inch by inch - apparently a controlled oxidation of the metals similar to rust. Some earlier products were less effective but this last one very good. Does it work - and last - yes. Birchwood Casey Superblue an effective blue process from my experiences. I can't ask for more than that.. Give some a try Akaroa - or sometime I'll come over to Aka and do a rifle for you..

Super blue, like all other cold blues I'm aware of is primarily the deposition of a Selenium dioxide coating. But super blue also has a couple of acids and phosphates that I think help the coating to adhere and etch into the steel.
The acids may also provide a oxide type coating that provides a level of rust protection but I would think the Selenium dioxide component is the main reason for the colour change and the other ingredients are to improve this adhesion and over all result.
General composition is available here: https://www.birchwoodcasey.com/conte...Gun%20Blue.pdf

I've used cold blues including Superblue in the past, the result is visually quite good. But they are not durable coatings and any wear, contact, or rubbing will very quickly show through to the white. Personally, the colour cold blues result in isn't to my taste, it's not quite right and I prefer a rust blue or for small parts if there is just one screw or something flame bluing.

This book: https://www.amazon.com/Firearm-Bluei...dp_ob_title_bk
Is a really good resource for understanding different options for finishing steel for firearms.