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ClintonH
03-16-2009, 12:29 PM
Some of the members here wanted a quick run down of how to do a Hot Black Oxide finish so here it is. It's very easy to do you just have to be careful with the salts, they are very corrosive. You'll want to wear some protective gear, I wear a face shield, gloves and respirator when I mix the salts.

What your going to need.

The salts are mixed from a combination of Lye, Ammonium nitrate and water. The original formula called for 5 pounds of Lye to 2.5 pounds of Ammonium Nitrate, to 1 gallon of water. I have been successful in scaling that mix to a lower quantity, just keep the ratio.
I could not find Ammonium Nitrate in Canada so I used Potassium Nitrate, you can also use Sodium Nitrate. They are all supposed to work equally well.

You need a pot big enough to fit the parts you plan to finish with enough room for a vigorous boil. I use a 2 gal enamel coated pot, it can't be galvanized or aluminium the salts will eat it and render your salts useless at the same time. I don't know if stainless will work I didn't want to waist the $$ to find out.

A burner to boil the salts, I use a propane fired Coleman camp stove, it's cheap and easy to store. Whatever you use make sure it will get hot eough, you will need a vigorous boil to get the deep black look. The first time I tried this I had just a "slow" boil and the parts came out brown, so it needs to be hot and move'in.

A few bucks of clean hot water to rinse your parts with after the boil, and to clean your pot, stove and anything else that comes into contact with the spray or boilover.

The hardest part and most important is the finish and cleaning of your parts. Black Oxide finish will magnify all the imperfections in the work piece. I found finishing with 100-120 grit on a belt sander to be about as course as you'll want unless you want a machined look. You must also clean the parts thoroughly, any oil will leave spots that will not take the oxide finish. Wear rubber gloves when you handle your parts as even the oil from your hands will be enough to wreck the finish. I start by giving it a quick wash with lacquer thinner and then a thorough cleaning with wax and grease remover. And finish off with a dip in hot water and wipe dry. From what I've read anything that removes/clean grease will work (fantastik, simple green etc..) just make sure there is no oil/grease.
Cleaned parts with the hanggers ready for the boil.

http://farm4.static.flickr.com/3635/3359274364_df0a928c0e_o.jpg


Now you can mix the salts. You'll want to do this outside where your going to be boiling, don't do this inside as the steam is corrosive. Start with cool water and gradually mix the Lye in until it is fully dissolved. Now mix in your Nitrate, it will gas off as you mix it in (wear a respirator) Mix it slowly as this will heat up as you mix. Now you ready to bring it to a boil.

Here's a picture of the setup I use. I save the haggers for the next job, makes everything go faster and they are clean from the last time.

http://farm4.static.flickr.com/3596/3358456103_c6c961b2ba_o.jpg

This is the Lye, Potassium Nitrate and a scale to get the ratios correct. Be careful handling the Lye it is very corrosive, wear safety gear

http://farm4.static.flickr.com/3562/3358456155_f4919856e5_o.jpg

Clinton

ClintonH
03-16-2009, 12:31 PM
This is the setup outside and a shot of the salts boiling.

http://farm4.static.flickr.com/3431/3358456267_1b34e0c61c_o.jpg

http://farm4.static.flickr.com/3659/3358456227_3821277829_o.jpg


The length of time you leave the parts in the bath will determine how dark your parts will turn out. I tried to take a picture of the various times and depth of colour but it's hard to see the difference in the picture. 5-10 minutes will give you a light brown finish . 15-20 minutes will give you a deep brown finish. 25-30 will give you the black finish 30 being the darkest. I did not see any better or darker finish after 30 minutes.
When I remove my parts from the bath I rinse them in hot water, you should do this quickly as the salts will ant to dry on. Don't worry if your parts have a red coating, this will wipe off with a rag or a toothbrush is what I use. I usually leave the parts in the hot water until I take the coating off.
This is a picture trying to show the various depth of colour.

http://farm4.static.flickr.com/3469/3358456359_7f00382b66_o.jpg
http://farm4.static.flickr.com/3603/3359274584_85023e38de_o.jpg

Clinton

ClintonH
03-16-2009, 12:34 PM
The red coating you get if you parts touch the sides or bottom of the pot.

http://farm4.static.flickr.com/3567/3359274458_a49767653b_o.jpg

Once the patrs are cleaned and dried they should be oiled. I use WD40 or ATF and soak them overnight.
Cleaned and dry.

http://farm4.static.flickr.com/3471/3358456323_478b8b2dd2_o.jpg

Oiled and wiped down.

http://farm4.static.flickr.com/3426/3359274548_c700946b5d_o.jpg


After you have removed your parts form the bath you must add water to replace the boil off. Take the salts off the burner and add the water slowly as it will boil as you add even off the burner. It takes awhile to cool down, don't let it solidify/crystalize. You cannot remelt and the mix will be shot. Store is a plastic or glass container (not metal), they should be good for another 10-15 uses.


Clinton

JBL37
03-16-2009, 12:43 PM
Nice work Clinton. That would have to be a summer time job for me. I do not like to work in the snow. JIm

ClintonH
03-16-2009, 12:46 PM
Nice work Clinton. That would have to be a summer time job for me. I do not like to work in the snow. JIm

Nether do I but It seems like it's never going to stop here. :D :confused:

Clinton

ligito
03-16-2009, 01:02 PM
Will it work on Aluminum?

bvd1940
03-16-2009, 01:03 PM
I was going to use cold blue, but this looks to be the way to go.
Thanks for your effort in posting the process, now back to lurking.:cool:
Freedom is not free!!

lynnl
03-16-2009, 01:11 PM
Nice job. And thanks for the info, I want to try that.

Do you mean ammonium nitrate is not even available for agricultural/gardening purposes in Canada? Good grief!

ClintonH
03-16-2009, 01:24 PM
Your welcome guys. No you can't get Ammonium nitrate in Canada, I had a heck of a time finding Potassium Nitrate.

I meant to include this info as well.

I have tested what will and will not work in the salts.

Aluminium - Not to finish just to see how it reacts. It does not take the finish incase anyone wants to know and it will dissolve in the salts.

Brass - Doesn't seem to be effected but it was a quick test so don't hold me to that. It may erode as it boils.

Galvanized - The galvanizing is dissolved instantly and the salts are shot, with my test anyway.

Stainless steel - Didn't really take any colour, maybe a ting of brown. Doesn't seem to effect the salts. I don't know what a large part or using a pot made of stainless would do, I tried a few washers. For someone that could get the mix cheap it might be something to try, this stuff is not cheap for me to mix.

Clinton

Just Bob Again
03-16-2009, 01:41 PM
I had a heck of a time finding Potassium Nitrate.

Stump remover, found in garden stores is reasonably pure potassium nitrate. I'm not sure that it's pure enough for this use, but may be worth a try. My understanding is that it IS available in Canada. Amazingly enough, given my unorthodox use of other household chemicals, I do actually use it on stumps.

ClintonH
03-16-2009, 01:44 PM
Stump remover, found in garden stores is reasonably pure potassium nitrate. I'm not sure that it's pure enough for this use, but may be worth a try. My understanding is that it IS available in Canada. Amazingly enough, given my unorthodox use of other household chemicals, I do actually use it on stumps.

No it's been pulled off the shelf, at least here in Alberta.:(

Clinton

Rusty Marlin
03-16-2009, 01:54 PM
Will it work on Aluminum?
It will EAT the aluminum and "kill" the salts.

moldmonkey
03-16-2009, 02:09 PM
Nice post. How about disposal?

lakeside53
03-16-2009, 02:52 PM
I'm collecting the parts to do just this... A propane deep fried Turkey cooker looks like the best choice, and out in the garden.

The salt mixture boils at around 285F (IIRC), so it's really easy to get a "steam explosion" if you add a wet part or particularly one that has a screw hole filled with water. Lye will take your eyes out... boiling or not.


So.. to be safe(r), I'm going to lower my stuff in from a few feet away - line and pulley, wear safety glasses and have a garden hose running to douse me if stuff happens.

Evan
03-16-2009, 02:55 PM
For disposal you can dilute and pour on the ground or down the sewer. None of the ingredients are environmentally hazardous. Lye, sodium nitrate and potassium nitrate are all available in food grade and ammonium nitrate is fertilizer.

ClintonH
03-16-2009, 03:00 PM
Yes you have to be safe, but I'm not sure you have to add your stuff from a few feet away. Just make sure your parts are dry and clean (I said that I think.:) ) I blow them dry before I boil them because any residue or streaks will show in the finish. When you lower your parts in the mix stops boiling anyway, until it heats the part enough to boil again so it's unlikely you will get a boil over from lowering parts in.

As far as disposal I have no idea. Haven't had to dispose of any yet, but lye is a cleaner and drain opener and the nitrate is a fertilizer so?? Anyone have any suggestion on this?
Ahh. Evan answered too quick. :)


Clinton

Just Bob Again
03-16-2009, 03:03 PM
No it's been pulled off the shelf, at least here in Alberta.:(

Clinton

Wow. Things are getting bad. Pretty soon you'll have to get a note faxed from your doctor before buying a pound of meat or salt. To make sure your cholesterol isn't too high and it's "safe" for you. Speaking of food, nitrates are used for curing meats. Should still be able to buy food-grade nitrates but may not be as readily available.

Evan
03-16-2009, 03:33 PM
Are you sure Clinton? I just phoned the local feed store and they have stump remover for $7 a pound and ammonium nitrate fertilizer, 44 bags in stock.

ClintonH
03-16-2009, 03:42 PM
Are you sure Clinton? I just phoned the local feed store and they have stump remover for $7 a pound and ammonium nitrate fertilizer, 44 bags in stock.

Well I phoned 5-6 feed stores around here (Edmonton) all said they had pulled it from sales just after 911 happened, they actually wanted my # cause they are supposed to report any inquirer on this. I also couldn't find any fertilizer or stump remover anywhere that contained ammonium/potassium/sodium nitrate, tried Home Depot, Rona, Home Hardware, Co-Op, True Value, Canadian Tire you name it I was looking. If you can get it in BC buy it cheap and send me some.:) I paid $28 for 5lbs from a hydroponics store.:confused:

Clinton

dan s
03-16-2009, 03:54 PM
If you can get it in BC buy it cheap and send me some.:) I paid $28 for 5lbs from a hydroponics store.:confused:

That will get Even on a watch list for sure :D

Mike Hunter
03-16-2009, 04:17 PM
Ok guys, been watching this topic with some interest. What you’re talking about is basic Caustic or Hot Salts bluing, something gunsmiths have been doing since the mid 30’s. So it’s not rocket science.
But it is a super saturated lye solution boiling at 280 deg, so still nasty stuff.
Use it here in the shop, I fire up the tanks about once a week, not because I want to… Don’t really care for the stuff… but comes with the territory.
Some hints;
That stuff will give you nasty burns, lye burns really hurt. Keep some vinegar handy, it will neutralize the lye, and make you smell good too. Get some of this on ya….quickly throw some vinegar on it.
This stuff will eat Al in a heartbeat, enough copper and brass will kill the solution. Will dissolve zinc in a heartbeat. Stainless and iron no problems.
This stuff will eat up wood pretty good, as well as clothing, shoes etc.
Rubber gloves, long sleeve shirts, pants and good shoes as well as face protection recommended.
Adding water to this solution when hot will cause boilover, think about it,the water wants to immediately evaporate. Need to add water, use a dipper or even better ice cubes.
This stuff will eventually “creep” out of the tank. Onto the floors walls etc, Keep that in mind when storing.

Enjoy

Mike Hunter

Evan
03-16-2009, 04:33 PM
That will get Even on a watch list for sure

I am certain I already am. My father used to do fusion research and I used to drive nukes around in the army.

My wife was mentioning she would like some sort of hedge maze in the field. I was thinking planting one for the satellites that looks like a one finger salute. :D

Just Bob Again
03-16-2009, 05:19 PM
I paid $28 for 5lbs from a hydroponics store.:confused:

Clinton

Not such a bad price. It's $5 or $8 a pound in the US in small packages. Cheaper if you get a big sack at the farm store but that stuff isn't very pure and it takes a lot of stumps to use up 50 pounds.

Seastar
03-16-2009, 05:25 PM
I have used Clinton's process on some firearms but much prefer the parkerizing process. It's much easier and does not use caustic chemicals.
Dark grey with zinc park and very dark almost black with manganese park.
Try it - you'l like it.
Bill

ClintonH
03-16-2009, 05:46 PM
Mike Hunter, I just post this up on request from other forum members, I posted info on the gun blueing guide in my previous posts. I still had requests on how I got the finish I do, that's why I posted this up. Your info is redundent if you read the thread.

Seastar, how much different is it using phosphoric acid than Lye? This (http://en.wikipedia.org/wiki/Parkerizing) is the process that your referring to correct?

Clinton

DENedbalek
03-16-2009, 05:51 PM
After you have removed your parts form the bath you must add water to replace the boil off. Take the salts off the burner and add the water slowly as it will boil as you add even off the burner. It takes awhile to cool down, don't let it solidify/crystalize. You cannot remelt and the mix will be shot. Store is a plastic or glass container (not metal), they should be good for another 10-15 uses.
Clinton

Clinton, I am a little slow, so I want to ask a follow up question specific to your finishing up procedure. If I follow you, you started with, say a gallon of water, and when you finish you'll have less than a gallon, so you then you add water to the warm solution to get back to a gallon. Correct? Than you let cool further, and finally store the cooled solution. You can re-heat the stored solution and go at it again. Correct?

Thanks for the write up.

Dwayne

RancherBill
03-16-2009, 06:42 PM
You might be able to find ammonium nitrate at a Farm Fertilizer Bulk Plant. They do custom blending for farmers and would have it as 60-0-0 fertiliser.

I sure they would give you a small pail full in exchange for a contributioon to the Friday Afternoon Social Fund.

Nobody will give you big amounts after Timothy McVeigh.

bob ward
03-16-2009, 07:12 PM
Clinton, many thanks for taking the time and trouble to provide that info.

loose nut
03-16-2009, 07:23 PM
Is that ammonium nitrate prilled (little round balls) or non-prilled or does it matter. You can still get it here in garden stores in small quantities.

ulav8r
03-16-2009, 08:48 PM
The hot water bath is good to remove all of the salts from the finished parts, but you will get deeper color if you use a cold water dip during the processing. Boil the parts for 10-15 minutes, then remove and dip in cold water, preferably ice water, and then return to the salts. Boil 5 minutes, dip in ice water, boil again. After 30 minutes total, dip in cold water again, then into boiling water to remove all salts. If there are no small crevices 5 minutes in clean boiling water should remove all salts from the parts. Some gun parts cannot be readily disassembled and will require 30 minutes boiling to remove all salts. Any salts left on the parts will draw moisture and corrode the parts. Oil as soon as the water evaporates from the hot parts.

Evan
03-16-2009, 09:26 PM
I have Clinton's permission to put the information on the ixian.ca gallery site so it will be easy to find in the future. I will probably have it online there by morning.

John Stevenson
03-17-2009, 05:13 AM
I get my parts commercially blacked at a hardening shop literally across the road from me, for what you have to drop the manager it isn't worth the hassle but that only my unique situation.

What I want to post about is they remove the parts from the mix, then into boiling water for about 10 - 15 minutes then quench off in de-watering oil.

It's either the quench or the oil that gives it the final blackness.
I know de-watering oil is easy to source as it's also sold with the cold black kits.

[EDIT]
Here's some Bridgy drawbars that have just been done.

http://www.stevenson-engineers.co.uk/files/drawbar1.jpg

.

rwf71
03-17-2009, 06:52 AM
As you may know from a thread I've had going here I'm in the process of building a homemade "turkey fryer" to try this myself after being inspired by the look of your parts in an earlier thread. BTW I ended up with a .055 jet in my burner & it looks GREAT so I'm building the stand to hold the burner & bottle now.

Thank You for taking the time to post this thread & pics, I really appreciate it ! Sure hope I can get the great looking results you do. Rick

J. Randall
03-18-2009, 12:39 AM
While the solution won't hurt a stainless item, it seems like I read somewhere in the past that the salts last longer if you use black iron, or regular steel tanks.
James

ClintonH
03-18-2009, 12:41 AM
While the solution won't hurt a stainless item, it seems like I read somewhere in the past that the salts last longer if you use black iron tanks.
James

Ok that confirms why all the articles I've read say to use an enamel plated pot. Thanks for the good info.

Clinton

JRouche
03-18-2009, 02:13 AM
Hey Clinton.. Great right up!!! Thanks for going through the steps and providing good pics!!! Im saving this thread locally on my computer. JR

Oh, and not to take away from Clintons great procedure. I just bought a gallon of brownells oxpho-blue. I like the stuff. Produces a nice bluing and it protects very well for those that are making their own tools. Highly recommended. I think I have enough to last my life time, doesnt take much. Prolly didnt need a gallon LOL

PTSideshow
03-18-2009, 09:48 AM
What I want to post about is they remove the parts from the mix, then into boiling water for about 10 - 15 minutes then quench off in de-watering oil.

It's either the quench or the oil that gives it the final blackness.
I know de-watering oil is easy to source as it's also sold with the cold black kits.

.

Would the de watering oil
As per this blurb form Brownells catalog site. The real professional - and longtime favorite - "after-bluing", one-step oil and protection treatment. Specially formulated; the molecules of oil actually displace the molecules of water still on the surface of the gun as it comes out of the final hot water rinse. Gives the gun a completely protected surface, ensuring your time spent on polishing and bluing will not be spoiled by rust under the oil. Also a superior rust preventive which neutralizes fingerprints, body acids and oils from handling and shooting. Provides a protective film with that proper "oiled and protected" feel preferred by many serious shooters and gun people. The standard by which other "after-bluing" oils are judged.

Be anything like the favorite water displacing oil Better known as WD-40?

Since they seem to have forgotten the MSDS link :D