Backyard hot caustic bluing

[Cobbler]

I was looking for the lye portion of the ingredients for hot caustic bluing at the local home improvement store and came across this product.



Here's the MSDS sheet on this product... http://www.summitbrands.com/retail_s...%20Crystal.pdf

According to the MSDS sheet, this stuff contains one popular formulation for hot caustic bluing in approximately the correct proportions. The "aluminum cuttings" look like something that was swept off a milling machine. Everything I have read about hot bluing says that aluminum "kills" the salts. With this in mind, I went ahead and conducted a test batch and determined that if that is the case, the aluminum present in this mixture is not in significant quantity to produce the nullifying effects.

With that in mind, I set up this contraption in the back yard. The setup consists of a Coleman camp stove, a small tank I bent and welded from 12ga mild steel, and a candy thermometer. Also present is a 5 gallon bucket of water for emergency self dunking and a charged garden hose.



Here's the little "bucket" for the small parts.


****DISCLAIMER****

This stuf is very toxic. Extreme caution must be taken to protect the user from comming in contact with the salts both in the dry form from the original container and from the solution as used here. Personal protective equipment would include but not limited to; full face splash shield, breather mask capable of protecting against the fumes this stuf produces, full rubber apron, gloves, arm protectors, rubber boots, etc... Even the fumes from this stuff, if it comes in contact with your skin, will cause burns.

**********

The drain cleaner is mixed with water at a ratio of 1 jug of drain cleaner per pint of water. The reaction which occurs when the drain cleaner is added to the water is both very violent and very exothermic... the stuff bubbles and splashes with great enthusiasm and gets very hot, very quickly. After the drain cleaner has gone into soulution, it is then heated to ~270 degrees Farenhiet. The parts are then suspended in the tank and "cooked" for 20 minutes. (Note... parts are completely degreased and then preheated in another tank on another Coleman camp stove prior to going into the bluing salts). After 20 minutes, the parts are returned to the preheat bath, which magically became the rinse bath! After a few minutes in the rinse bath, I took the parts to the basement washtub, and continued running clean, hot water over the parts while scrubbing them with an old tooth brush. The final step was to hose the parts down with oil.

Here's the end result... a homebuilt DeHaas Chickopee Centerfire built as a pistol in 22 Hornet.

[JCHannum]

Thanks for the bluing information. It appears do-able and looks like it does a nice job.

The Chicopee also looks very nice. Any other photos and build notes would be appreciated.

[RWO]

You can buy plain lye ( NaOH) without the aluminum chips at many grocery and hardware stores. "Red Devil" is one brand. The aluminum is added in the drain cleaner to generate gas which agitates the solution in the drain to make it more effective as a clog remover. Straight lye doesn't do that.

You didn't mention the nitrate part of the recipe. I assume you added 33% ammonium nitrate per the recipe in Dunlap's, "Gunsmithing"?

RWO

[Cobbler]

You can buy plain lye ( NaOH) without the aluminum chips at many grocery and hardware stores. "Red Devil" is one brand. The aluminum is added in the drain cleaner to generate gas which agitates the solution in the drain to make it more effective as a clog remover. Straight lye doesn't do that.

You didn't mention the nitrate part of the recipe. I assume you added 33% ammonium nitrate per the recipe in Dunlap's, "Gunsmithing"?

RWO

This Drain Out product is a one-stop-shop for the chemicals. All I do is add it to water. The contents, according to the MSDS listed above, are;
Aluminum cuttings - 1-5%
Sodium Hydroxide - 30-60%
Sodium Nitrate - 15-40%

I tried the stuff as-is considering the mid point of the percent ranges listed are pretty close to one of the home-brew recipies. Again, this bluing solution is simply 1 jug of Drain Out per pint of water.

[radkins]

How difficult would it be to remove the Aluminum chips?

[chriskat]

Absolutely beautiful. Also gives me hope, if I ever finish my Vault Lock rifle I am planning on using a .30 cal barrel I have to built two pistols based on the vault lock design.

Got any sketches of how you managed the pisto grip?

Jeff

[38_Cal]

Hoo, boy, put on the hat I took off after the B company let me go 2 1/2 years ago. Aluminum will not kill your salts, but at the right concentration, and with the "right" contaminants in your salts tank, you can get spotting on your blued parts...a false plating effect, of aluminum on the steel that will not blue.

Commercial salts are sodium nitrate, sodium nitrite and sodium hydroxide. I don't have the proportions used, but Angier's book, Firearms Bluing & Browning, does give some guidance. Brownells formula works at 10 pounds of dry salt per gallon of water, and boils vigorously at 292* F. Control your temperature by adding water or letting some boil off, you'll get a better finish that's more predictable.

David

[radkins]

I assume removing the Aluminum is not practical?

[Cobbler]

I don't think removing the aluminum cuttings is either practical or necessary. I discussed this issue with my Brother-in-law who has a PhD in chemistry and he thinks that the aluminum at the stated concentrations would simply be consumed by the reaction with the sodium hydroxide and that, worst case scenario, you would need to replace some of the NaOH (Red Devil lye) to bring things back to the desired concentrations.

I suppose if you have one of those aluminum magnets that you might as well take the chips out though

[38_Cal]

Just don't use an aluminum sieve!

David