Questions On Bluing
Posted 23 August 2011 - 10:21 AM
Sorry for the litany of questions, just trying to understand the method. Thanks for any help on this.
Posted 24 August 2011 - 05:14 AM
You own any guns, Jeremy?
It's just as durable as that, because, well, it's the same thing.
When a blade is hot-blued, the entire blade comes out black, then the bluing is sanded off of the nickel bearing layers, as they remain just a little higher than the tool steel layer after etching. That's how the contrast is achieved.
The salts used are extremely caustic and even slightly dangerous, as the salt bath is maintained at around 300. The cleaned parts are submerged in the molten salts for about 1/2 hour and then followed with hot water and oil baths to clean and protect the fresh finish.
That is the basic bluing outline.
Fittings of Damascus and non-stainless steels, blued by the same process, are very beautiful and well worth the effort.
Please take a cruise through my web site and see the different results attainable.
Posted 24 August 2011 - 07:20 AM
Thank you for the reply. It was actually several of your knives (that I rather enjoy staring at for long periods of time) that got me thinking about this. I am familiar with the bluing on guns, but I must say I never thought about how it was actually done. You mentioned a hot salt bath-is the bluing achieved as a result of the reaction with the salt or is there some kind of liquid or other substance that is the bluing agent? Sorry for the dumb follow-up question, I guess for some reason I always just assumed the bluing was some kind of liquid that the steel was submerged in. Anyway, thanks again.
Posted 24 August 2011 - 09:44 AM
"Salt" is a term used lightly here, it's not your salt that you use on your french fries. It is chemically classified as a "salt". The only other element involved is H2O - water.
The salts are expensive and must be shipped Haz Mat.
Posted 04 September 2011 - 07:01 AM
What about other techniques like the black oxide coatings? I've used those on tools and the baths, while a bit toxic, are at least room temperature. Is the hot blue that much better? I've never tried it mainly because of the need for temperature control.
John Updike - The Dance of Solids
Posted 12 December 2011 - 01:52 PM
My initial shopping list for getting into hot bluing calls for: stainless thermometer, 2 small iron tanks that I will use on a 2 burner coleman stove, small parts basket, cleaner/degreaser, bluing salts, water displacement oil, chemical gloves.
Posted 22 December 2011 - 11:08 AM
Rust Bluing will produce a great finish, but it is time consuming. A sweat box can be something as simple as hanging the parts in the bathroom while you take a shower, but some form of generating a warm moist enviornment will greatly speed up the process.
For hot bluing, if you are using a coleman stove that is propane, get a converter to hook it up to a 20 pound tank. The 1 pound bottles get cold quickly which reduces the output and you wont be able to maintain the temperature you need. Even with the small tanks, it is going to take some time to get up to temperature.
Get a face shield as well. Hot bluing can be a bit explosive at times --especially if water is added incorrectly.
Posted 07 January 2012 - 06:53 PM
I'm considering doing some hot blueing, on some knives, and want to know how you deal with the caustic atmosphere it creates?
How do you store the salts and equipment so it doesn't rust everything in your shop.
I have had experience with muratic acid, it will rust equipment in your shop with it in sealed containers.
Posted 14 January 2012 - 09:17 AM
I do bluing outside. It may be a bit of a pain to do so, but that way it keeps things in good shape in the shop. I store bluing in a tank with a lid that has a seal on it much like what Brownells sells.
Posted 17 January 2012 - 07:08 PM
In other words, there are no caustic gases running rampant around the shop.
A cover for your tank is mostly to keep things OUT of the tank - not the salt IN the tank.
When bluing, there is no "caustic atmosphere" other than maybe some spitting and sputtering that would emit droplets of caustic salt in the immediate bluing area.
I do mine out in the middle of my forge area on the concrete floor.