Author Topic: Hot bluing at Home (With Pics)  (Read 4083 times)

0 Members and 1 Guest are viewing this topic.

Offline ThompsonCustom

  • Hero Member
  • *****
  • Posts: 1052
Hot bluing at Home (With Pics)
« on: April 07, 2013, 10:29:28 AM »
Over the weekend I finally got to a project I have been wanting to try for awhile now but just haven't had the time and that is hot bluing. I would like to some day be able to do high gloss hot bluing and that's what I was going for but my level of polish needs to be a lot higher as it turned out more of a semi gloss.

Here is the pic of the mag before anything was done. Note next to the number 5 there is a grey mark, I had some sulfuric acid on my hands and just happened to grab my mag and that's what happened about 1 year ago. Other than that there is just some normal wear and tear on the mag.

Now for the prep work, I did this all by hand with different levels of sand paper and no polish and that's where the glossiness comes from. I started with 180 and worked up to 3000grit paper but there are scratch marks that I didn't get out and by the end of all the hand sanding I didn't care. I think I need a sand blaster and some polish wheels for my bend grinder before I do this again.

Here a pic after the prep work. 

Now I cleaned the parts with acetone and set them aside. Next I went out to the grill and heated up the pot of 5 lbs potassium nitrate(kno3). Believe it or not I had 3 lbs just laying around from past experiments but I wanted a little more so I went to the local farm and fleet and got the closest thing they had. Gorgons Stump remover is 99% kno3 so I bought 2 pounds of that and threw it in the pot.

After about an hour the KNO3 turned from white powder to black ash and finally into a yellow liquid. At this point I hung the parts from some copper wires and submerged them for 30 mins. After they were done I removed them and put them in a bath of motor oil over night.

The next morning they appeared to have a white crust on them in some spots but it was just cooled kno3 and came off with a little water.

Here is the pic of the finished Mag.   

Overall it was a fun project and tho it doesn't have the shine I wanted I'm still happy with the results.

« Last Edit: April 07, 2013, 10:32:54 AM by ThompsonCustom » Current Deals:
Faxon 16" Pencil Barrel $148
21% off all magpul products code: "magpul"

Offline adrian

  • Sr. Member
  • ****
  • Posts: 324
Re: Hot bluing at Home (With Pics)
« Reply #1 on: April 07, 2013, 12:45:57 PM »
     Hiya ThompsonCustom, and very nice result, looks shiny to me. The only hot bluing I was interested in ta date was related to this TS before deciding to just polycoat it black.
     The custom shop mentioned that the problem area is the front and back straps, and bluing would result is pitting/holes in and around all those little bumps, I like em and was not considering reducing the backstraps just to have the bluing come out looking good. So ,for me,needed the function more than the fashion. Wonder if thats why CZ only blues the slide on this model.
     Was this a project a prelude to another ya have in mind??? Thanks for sharing, be well

Offline ThompsonCustom

  • Hero Member
  • *****
  • Posts: 1052
Re: Hot bluing at Home (With Pics)
« Reply #2 on: April 08, 2013, 04:22:52 PM »
Hmmm I can't see why bluing would cause pitting unless there using a Lye based formula. What kind of bluing were you thinking a high gloss or just standard hot bluing? If you want a standard blue I would think anyone that specializes in gun coats could do it. But from my research it looks like the high gloss in high gloss bluing is achieved through polish and buffing wheels so I guess my worry would be removing the sharpness from the checkering.

Sounds like Ford's does a good job and I know you can send colts back to the factory to be refinished in high gloss but both are costly ford's 275 and I think colt is 350, I like CZC but if I was going to have a gun refinish I would send it somewhere were that's what they do all day long everyday.

Was this a project a prelude to another ya have in mind???
Maybe, Kind of hope so as my CZ 75b is showing some wear and tear from being carried everyday and I think a super high gloss bluing would look fantastic on a CZ but as you can see from above I have a long way to go before I think about redoing my beloved CZ. Current Deals:
Faxon 16" Pencil Barrel $148
21% off all magpul products code: "magpul"

Offline Chiz

  • Jr. Member
  • **
  • Posts: 90
  • 480-316-8849
Re: Hot bluing at Home (With Pics)
« Reply #3 on: April 19, 2013, 11:40:31 PM »
I work at a custom gun shop and we do a ton of hot bluing with large tanks. We use 3 tanks in the process plus there is a ton of prep work and post clean up of parts. I'll try to keep this short as possible if anyone would want more info let me know.

#1. Tank, Hot bluing salts with distilled water at 300 degrees.
#2. Tank, Hot tap water at 225 degrees for rinse.
#3. Tank, Outside temp. tap water and lubricant.

Prep of parts varies depending on the look that the customer wants.
* Glossy look. Depending on the part we will start with the least aggressive sandpaper as the part needs to remove rust, pits, scratches.
* Work up to 500 or 600 wet paper with mineral spirits. (On some guns I'll even go up to 1200 but never past that)
* Polish on buffing wheel to get the parts to the point where they look like they have been chromed.
* Scrub parts with rubbing alcohol and do it again for good measures. You don't want any finger prints, oil dirt etc to affect your bluing.
* We use wire to suspend key parts from touching anything, screws, and internal parts can be placed on a fine mesh screen basket.
* Insert parts in hot salts, Tank #1, once 300 degree has been stabilized, soak for 15 mins. (depends on your mix)
* Remove parts from salts and rinse in the fresh hot water tank #2.
* Move parts to tank #3 with water and lubricant for hand and soft brushing to get oxidation from parts
* Use compressed air to dry parts, once dry use soft cloth with liberal amounts of WD-40 to coat parts and rub to remove any excess oxidation.
* The part can sit with WD 40 on it until you are ready to re-assemble gun.
* Use mineral spirits to wipe down parts and blow dry and use soft cloth to polish parts.
* If you want a Matte finish we follow the same procedure but we will sand to 500 and bead blast the parts, clean the parts and then use the same bluing procedure.   

Professional hot bluing will not cause pitting. I cant speak to home grown bluing. If you happen to slip up and add a piece of aluminum into the tank it will dissapear on you! Results will vary depending on the type of material the gun is made from or if it was heat treated. 
Ron (Chiz) Chisler
CZ SP01 Shadow ACCU
Blackhawk S.S. 44 Mag/Scope
Sig Platinum Elite .45
Sig P230 .380
S&W model 67
Ruger Mark lll Hunter Target
Ruger 22 revolver

Offline schmeky

  • Hero Member
  • *****
  • Posts: 2745
Re: Hot bluing at Home (With Pics)
« Reply #4 on: April 20, 2013, 10:21:14 AM »
Lye won't pit the metal once the lye is in solution.  I hot blue quite a bit and I make my salts in house with this simple, inexpensive recipe:

5 lbs 100% Lye
2.5 lbs 15-0-0 or 16-0-0 Nitrate of Soda
2 gallons water
Propane cooker with steel or stainless steel pot, DO NOT USE ALUMINUM, the salts solution will dissolve it in seconds.

Mix 5 lbs of lye into the water s-l-o-w-l-y at ambient temp until it is completely dissolved.  Careful, lots of ammonium gases are released, wear eye protection and long sleeve clothing.  Slowly heat the solution while adding the 2.5 lbs of Nitrate of Soda, bring solution up to 285-295 degrees F.  Make certain parts are degreased, as well as the wire you hang parts on.  Immerse and keep temp steady, about 30 minutes and you have a super rich, deep, black-blue part.  Gorgeous. 

Remove items and rinse thoroughly with water to remove the salts solution, blow dry and oil down.  Done.

Offline HankC1

  • Jr. Member
  • **
  • Posts: 77
Re: Hot bluing at Home (With Pics)
« Reply #5 on: May 19, 2013, 08:17:56 PM »
Is potassium nitrate reusable after hot bluing? How to tell if the salt is still good? Lye is not available anymore I believe.