Need advise on rust bluing prep

[MBiz]

Hello everyone,
I am preparing this old Carabine FN Browning 1900 for rust bluing and I am not sure how far I should go with the sanding. Following the article I read, it is not necessary to go further than 320 grits. On the picture attached, which is somehow magnified, the lower part of the receiver was sanded to 320. However, we can still see streak marks. Following your experience, is this ready for rust bluing? The upper part, where the address appears, will be sand off and the marking (address) will be laser engraved. Thank you for your help.

 

[Keithjohn]

It will show through . When you can't see Anything and think it's perfect give it two more go overs

 

[Mauser98]

I agree, those fine scratches will show in the bluing.

My procedure is to sand with progressively finer wet/dry sandpaper. With each grit, I try to eliminate all the scratches that were made by the previous grit. I usually go up to 400 grit but even this grit may leave tiny scratches and swirls in the metal.

To get rid of these, I finish the polishing by going over the work with a good rub-down with a 3M ultra-fine Scotch Brite pad with a solid backing. The result is a bright gloss finish.

 

[dilly]

I disagree with above two posts. I never go past 320 when RUST bluing. Leave something for the acid to etch and rust to form evenly on. Those minor scratches disappear when you card off the rust 6 or 7 times. Too fine a polish and you get uneven rusting.

The pitting over the stampings will also show unfortunately.

 

[sean69]

it depends on the solution, method and application you are using. What does the manufacturer say? What you have there with some of the 'hotter' solutions will be just fine. As mentioned most acid solutions need a substrate to start working on and will be carded off, for those solutions the higher the polish the more difficulty your solution will have 'biting', higher polish = more turns, and you may not actually get it to blue at all!.
Weaker wipe on/wipe off cold blue solutions will definitely need a higher polish.
I can see at least 4 little dings in your polished area that will show no matter what solution you use.

Also to consider, not all abrasives are made the same, economy brands are not particularly even and show an uneven scratch pattern - nor will you find the grit sizes consistent from brand to brand. Use a high quality abrasive.

So your answer is "It depends"
- what solution are you using?
- what does the manufacturer say?

Your best bet is to figure out what the composition of the metal is, get a couple of scraps and run a few tests with different levels of polish.

Me? I've never gone past 400 grit (SIA Abrasives) and as low as 280 grit - which worked fine for the Pecatonica River browning solution.

 

[MBiz]

Thank you all for your insight. From the picture below, you can see how bag was the "carcass". I had to start with a 40 grits sand paper. Yes, there is a few dings here and there but there are so deep, that if I tried to remove all of them, they will be no steel left. It is no easy to sand and polish such a receiver. I think it will be dangerous to use a buffer wheel, which I intend to use on the barrel.
SIA is my main supplier for wood abrasive supplies. I chose from their steel line the 2-1/2 x 5" Velcro back sheet to mount on sanding block. I will see how it performs. I will polish the entire receiver up to 320 grits. As I mentioned, I will sand off the address and have it laser re-engraved.
For the bluing solution, I have two recipes. To increase the acidity of the bluing solution, which of the compounds should I increase?

Copper sulphate # # #1.8 g
Sol. Ferric chloride (29%)12.5 g
Nitric acid D 1.427.2 g
Alcohol, denatured2.5 g
Distilled water to make to 100 cc

1,2 g de sulfate de cuivre
4 g de sulfate de fer
5,6 g de perchlorure de fer
0,5 g d'acide chlorhydrique
100cc d’au distillée

 

[guntech]

I disagree with above two posts. I never go past 320 when RUST bluing. Leave something for the acid to etch and rust to form evenly on. Those minor scratches disappear when you card off the rust 6 or 7 times. Too fine a polish and you get uneven rusting.

I agree with this...

Just polish a bit more with 320 getting all the "lines' lined up... the 'scratches' appear worse than they are, because they are not 'in line'...

 

[sean69]

I think it will be dangerous to use a buffer wheel, which I intend to use on the barrel.

I personally would not use the wheel on anything - if you can chuck the barrel up in a lathe and use either a lathe file or back some of your sandpaper with a lathe file.

SIA is my main supplier for wood abrasive supplies.

Good stuff

For the bluing solution, I have two recipes. To increase the acidity of the bluing solution, which of the compounds should I increase?

Copper sulphate # # #1.8 g
Sol. Ferric chloride (29%)12.5 g
Nitric acid D 1.427.2 g
Alcohol, denatured2.5 g
Distilled water to make to 100 cc

1,2 g de sulfate de cuivre
4 g de sulfate de fer
5,6 g de perchlorure de fer
0,5 g d'acide chlorhydrique
100cc d’au distillée

OK - you got stones, I'll give you that! If ~I~ were to roll my own solutions, I would definitely not proceed to the real deal with running a bunch of tests on scraps. Those acids (Nitric and d'acide chlorhydriqu = Hydrochloric?) are available in many different concentrations/grades (lab to fuming) White fuming Nitric acid is incredibly expensive and insanely dangerous - you probably don't need to increase the acidity, you should be able to put a finger in it (the completed solution, not the acid.... don't stick your finger in acid. I can promise it will hurt) and not experience any discomfort.

From the timbre of your question ("which of the compounds should I increase") I would hazard that your experience with caustic chemicals (that can actually kill you) is limited. My recommendation would be:

- send the recipe to a lab that has the equipment and experience

OR

- back burner the roll your own plan and buy a bottle of PJs solution.

Try a couple of the commercial offerings first till you get the hang of the prep and process then start experimenting.

 

[dilly]

- back burner the roll your own plan and buy a bottle of PJs solution.

With this, I agree...easy, safe and cheaper

 

[sean69]

I suppose another option would be to RUST BROWN it, less risky and the small little defects you are gonna have will not look out of place...

That and if you do get a hold of even a mild Nitric Acid, you can fume blue/brown it.

 

[Waba]

I fume browned a Cooey model 60 with good results but subsequent projects had less predictable behavior.
I have used a solution similar to OP's nitric acid formula on blades with good results.
The last project was making a new floorplate for a mag modified NAACO Grizzley 22. I used a very simple solution of ferric chloride mixed with distilled water (to the approximate colour of urine). That was a slow process but it worked out just great and I will be using it if and when I ever finish off my underhammer carbine.

I am with sean69 on the subject of abrasive paper. It has been difficult to find consistent grit for the last 20 yrs, I'll swear that some 600 stuff I used had 180 size particles in it. That is a real annoyance when you spend hours hand finishing a blade or anything else. 320 is the sweet spot for most gun parts, in my opinion.

 

[marshall]

I will add, if you want Flat sides, don't use valcro back paper, it will just follow the dips, But if it is not flat and you want flat, that can take a hell of a sanding, or draw filing.
that poor old gun looks like more work than I would do, But have spent a lot of time, just for something to do, and it was a challenge, on stuff.
When you do the last sanding, make sure you go in a straight line

 

[FarmerDanz]

Too fine a polish and you get uneven rusting.

Experience talking.

 

[MBiz]

I personally would not use the wheel on anything - if you can chuck the barrel up in a lathe and use either a lathe file or back some of your sandpaper with a lathe file.




Good stuff




OK - you got stones, I'll give you that! If ~I~ were to roll my own solutions, I would definitely not proceed to the real deal with running a bunch of tests on scraps. Those acids (Nitric and d'acide chlorhydriqu = Hydrochloric?) are available in many different concentrations/grades (lab to fuming) White fuming Nitric acid is incredibly expensive and insanely dangerous - you probably don't need to increase the acidity, you should be able to put a finger in it (the completed solution, not the acid.... don't stick your finger in acid. I can promise it will hurt) and not experience any discomfort.

From the timbre of your question ("which of the compounds should I increase") I would hazard that your experience with caustic chemicals (that can actually kill you) is limited. My recommendation would be:

- send the recipe to a lab that has the equipment and experience

OR

- back burner the roll your own plan and buy a bottle of PJs solution.

Try a couple of the commercial offerings first till you get the hang of the prep and process then start experimenting.

It appears, I diagonally read your post. I thought that just by changing slightly the concentration of one the acidic components of the solution, it could give more bite to the bluing solution and therefore have more effect on "blurring" the scratches left by the polishing. Along the same line of thought, would changing the concentration of one or more of the compound in the bluing solution affect to final color of the bluing on the metal?

Thank you for the warning regarding the mixing of these potentially toxic compounds. Well noted.

BTW, I have to say that the tobacco color oxidation of the metal of your Winchester and the wood color choice are superb. Did you do the finishing and have you done a post on it?

 

[sean69]

I thought that just by changing slightly the concentration of one the acidic components of the solution, it could give more bite to the bluing solution and therefore have more effect on "blurring" the scratches left by the polishing.

On reflection, and this is all assumption at the moment - the level of acid in any solution I have used is not high enough to actually damage the metal, just enough to 'convince' it to start rusting under the right conditions. That being said a weaker solution (that still kick starts the rusting process) may be more appropriate as it should be more forgiving in the application. i.e. less streaking, more even rusting (which is the goal - EVEN rust)
Getting rid of the sanding is part of the carding process - you are carding off the surface rust, each turn take a little more material with it. after a few turns the sanding marks are carded away. Those dings you have will not go away with carding. They are too deep. So as mentioned by several your goals are:

- even consistent metal prep (sanding/polishing)

- even consistent surface prep (CLEAN!!CLEAN!!CLEAN)

- even consistent application of solution

- even consistent rusting and carding.

Any divergence from that means you will get uneven colour - which sometimes is not bad for a browning job (more interesting) but looks terrible on a bluing job.

Along the same line of thought, would changing the concentration of one or more of the compound in the bluing solution affect to final color of the bluing on the metal?

Yes. It was fairly common to add different chemicals and minerals to solutions to affect the final colour, can't tell you exactly what or how as the metal composition itself plays a major role in final colour. Nor have I ever tried to alter the colour - to me that is all academic. You might try looking up a little book: https://www.abebooks.com/book-search/title/firearm-blueing-and-browning/author/angier/
You might luck out and find a used copy somewhere.

Thank you for the warning regarding the mixing of these potentially toxic compounds. Well noted.

Stay safe

BTW, I have to say that the tobacco color oxidation of the metal of your Winchester and the wood color choice are superb. Did you do the finishing and have you done a post on it?

Thanks!

I did 2 Winchester 1892s carved the stocks and all the metal work. one .44-40 and the other .25-20 Both browned using Pecatonica River browning. I don't recall posting anything about the browning process on here, but at least one of them has more pics on my FaceBook site https://www.facebook.com/kimballarms/ and on my instagram https://www.instagram.com/kimball_arms/ Which probably has shots of my browning box (now currently filled with pandemic supplies!)

 

[MBiz]

Any of you remember, it seems to me, someone made a post on making a propane hot water thank burner. Or, someone can share information.
Thanks

 

[FarmerDanz]

Put a tool box on a BBQ? Done.

 

[sean69]

Any of you remember, it seems to me, someone made a post on making a propane hot water thank burner. Or, someone can share information.
Thanks

I have a 3x40,000 btu camp stove, cut up some eaves troughs for tanks. works just fine. stove cost me $75 from kijiji

 

[MBiz]

A little update on FN restauration project.

The receiver evolution

The blue color is a light effect

Now working on the forearm

If you have any advice for my project, there are welcome. I am a novice in this field.

 

[sean69]

A little update on FN restauration project.

The receiver evolution

The blue color is a light effect

Now working on the forearm

If you have any advice for my project, there are welcome. I am a novice in this field.

That looks great ... what solution did you wind up using?