Talk:Bluing (steel)

Heat treating

How does this relate to the blue finish one gets by simply heating steel or to "blue srping steel"? (See martensite). —BenFrantzDale 05:20, 6 December 2005 (UTC)

In gunsmithing terms that'd be "salt bluing," which was always rather rare, and more common in Europe than in North America. Pre-World-War-I production Lugers from the Mauser plant often had many of the small parts salt-blued (that is, immersed in molten salt until the martensite composition gave the desired surface color). It was both a heat treatment and a cosmetic coloring process, and the uniformity of color on the small parts was intended to show off the skill and technical prowess of the manufacturer.

Please quit using an end ) in the URL as HTML does not like it. Captain Cummings (68.48.36.183 (talk) 23:54, 2 June 2008 (UTC)). Thanks

I would like to add some comments about how this process related to blacksmithing. I believe that the process that blacksmiths use to blacken their forged pieces results in the same finish. After hot forging the piece will be naturally corroded. Allowing it to cool to the point that is can be coated with wax and then allowed to cool completely results in a hard and very black finish. Some people, me included, believe this how blacksmith got their name. They worked the black metal. I am not a metallurgist or chemist so I am not certain that this process results in the same finish. Could someone with more technical knowledge confirm that it is the same finish?

Dc6482 (talk) 18:44, 5 May 2011 (UTC)

That's not bluing, it's just laziness. It certainly doesn't give a particular hard, black or corrosion resistant finish.

Mild steel (unless it's bright drawn) is usually supplied with this black oxide finish. However that's produced by a rolling mill, not by hand forging. It's somewhat resistant, and is very black. When wrought iron is hand-smithed, you'll also get something of a black oxide finish. When mild steel is smithed though, the scale produced isn't thick enough or strong enough to make a useful finish. Wax is always applied cold. Whilst many smiths do just wax over hammer scale, it's a bit shoddy and certainly not a resistant finish. A better finish, and very popular, is to apply a hot oil finish. This can be brown, blue or black, depending on the oil used (vegetable, mineral motor oil, used mineral motor oil). It's quite a good finish for indoor use, although it's not as good as bluing for weather resistance.

Traditional smithing's finish for gunsmithing was browning, not bluing. Deserves an article, if we don't already have it. It's mostly a controlled rusting to produce the unhydrated Fe(III) oxide (brown rust). This is produced carefully, brushed and oiled. Unlike most rust, it can then produce a surface that's fairly impermeable and doesn't rust further (unlike the common hydrated red rust).

Neither of these are bluing (even a blue oil finish). Bluing is a chemical change to the surface, brought about by supplying more than just oxygen. Andy Dingley (talk) 20:13, 5 May 2011 (UTC)

Title

I think the modifier on the title (steel) should be changed, because this process can be applied to other metals. For instance, the military documents in the references section state that it can be applied to wrought iron. Perhaps the modifier should be metal or ferrous metal. --Wizard191 (talk) 22:42, 7 September 2008 (UTC)

Black oxide

I'm considering making a black oxide article, however, this article seems to have a lot of info on it. Upon reading the article I'm not sure if they aren't the same thing. Also, the military references refer directly to black oxide. So I guess my question is: 1. are they the same? 2. If not what's the difference? --Wizard191 (talk) 23:13, 7 September 2008 (UTC)

Black oxide is a true gun bluing. However, not all gun bluing is black oxide based. As you note, the MIL references and standards mentioned do refer directly to black oxide. Take a look at the Parkerizing and Phosphate conversion coating articles; one is on historical Parkerizing, and the other is on modern phosphate coatings. Perhaps the same kind of treatment would be worth applying here, too. "Bluing" is used more in an historical firearms terminology usage, whereas "black oxide" is used more in modern engineering terminology, for firearms as well as for non-firearms. Yaf (talk) 01:33, 8 September 2008 (UTC)

OK...let me make sure I understand this correctly. Bluing is just a firearms term for a black oxide coating applied to guns. However, it is used. Yes? If this is the case perhaps the modifier on the title should be changed to "guns".

Just for clarification I am looking at black oxide from the engineering side of things, and know nothing about firearms or its terminology. --Wizard191 (talk) 11:59, 8 September 2008 (UTC)

Black oxide is but one type of bluing for firearms; there are other types of bluing used on firearms, too. (Hot bluing vs. cold bluing, and hot bluing versus "hot and cold" mixed bluing, for example.) Black oxide is also used to refer to thicker bluing that is black oxide based. "Bluing" is also used to refer to an historical protection against corrosion for steel parts in general, such as used in wind up clocks, firearms, internal gears in fishing reels, and other similar precision-machined steel parts that are subject to corrosion. So, bluing is not a "gun-only" terminology. Because bluing does not change the dimensions of steel parts by an easily-measured amount, it has long been used to achieve corrosion resistance for steel parts, while always ignoring any tolerance buildup for mechanical dimensions of blued steel parts versus the same unblued steel parts. On the other hand, black oxide coatings typically refer to coatings that are much, much thicker, and that often do change the measured dimensions of protected steel parts by an easily measurable amount. So, "Bluing (firearms)" would not really be an accurate title. Why not have an article on "Bluing" and another article on "Black oxide coatings", with the historical usages centering on "Bluing", and with the modern usages centering on "Black oxide coatings", with a differentiator disclaimer at the heading of the article that was worded similar to what is used in the Parkerizing and Phosphate conversion coating articles. This would make the encyclopedia more useful to both non-technical users (who would be looking for bluing) and for technical users (who would be looking for black oxide coatings). With the appropriate discrimination wording line at the head of each article, this would work well. Yaf (talk) 18:11, 8 September 2008 (UTC)

Having two articles is perfectly fine by me. I was going to make a "black oxide" article, but then I found this one, and wasn't sure if it was the same thing, but you have cleared that up for me. I'll go ahead and make the article then. Thanks for the info! --Wizard191 (talk) 18:25, 8 September 2008 (UTC)

Yikes! My laziness seems to have set a precedent. I was the one who made the link between Parkerizing and Phosphate conversion coating, realizing that they were the same thing. I actually think they should be merged, but I was mostly just lazy. I foresaw a dispute on the names, because it "phosphate converstion" is easily the more common name in industry, but "parkerizing" appears to be better known on Wikipedia. So I just put in hatnotes so people would clue in to also look elsewhere. I also think black oxide and bluing (steel) should be merged. I don't really want to lead that effort, but please don't enshrine my past mistakes.--Yannick (talk) 15:52, 13 June 2009 (UTC)

Volume Change of Iron Oxide

I was doing some calculations based on the beginning statement: "the black oxide of iron, which occupies the same volume as metallic iron." According to the Pilling-Bedworth ratio, http://en.wikipedia.org/wiki/Pilling-Bedworth_ratio, this statement is not true. It has a volume change of about 2. I suggest that we change it unless I made a mistake somewhere.

Tycedi (talk) 18:03, 1 November 2010 (UTC)