Plum colored bluing?

[gman51]

The purple coloring is a love hate thing. Like most anything beauty is in the eye of the beholder.

 

[hittman77]

Some times you even end up with lightening strikes.

 

[2152hq]

What we see is any number of causes. It runs all the way from the metal and the way its heat treated to the chemicals used. .....

I agree with this, there's just no single problem involved.
The bluing being the 'hot salt blue' process.
You can get some funny colors doing rust blue as well, but that is usually from just not keeping the process and surfaces clean during the cycles.

Some parts when hot salt blued come out of the bath reddish colored. Others a very nice blue and then turn to the red/plum color over time. That time may be anything from a few days/weeks to a year or more before the color change occurs.

Older cast steel frames like single shot break open shotguns, 'boys' type single shot rifles and the like are suspect for coming out with the plum color.
Blame the steel?, they do sell some kind a special chemical to add to the bath for doing such parts to avoid the red color. There's also a few tricks juggling the temp and an ice water dunking that can sometimes seem to avoid the plum look.

I had an S ser# Mod57 that the side plate turned a shade of plum color,,not real noticable but if looked at in sunlight it was. I bought the gun NIB in the 60's so I knew it wasn't a reblue. When I went to sell it many years later, the side plate color was a big issue as the gun was 'positively a reblue' the experts said. The bbl and cyl retained their nice blue color, It's not uncommon for magnum cal cyl and bbls to turn plum. Heat-treat? and or steel composition?

Ruger folks almost expect the color on certain vintages of the SA's. It's a badge of originality of finish. Did the investment cast mfg method or alloy used have something to do with it?

A hot blued Brit SMLE receiver will usually turn reddish after a time, as will some Mauser actions. Again not all exhibit the red response but it did show up often when sporterizing these was more common and you'd see a lot of them in for a reblue.
It was pretty cheap some years ago too,, and most every shop of any size did hot blue. Not like now with all the regs pertaining to the process and the chemicals.

There's just so many variables involved that can lead to the color difference not including the individual gun mechanic doing the bluing.

 

[CAJUNLAWYER]

Let us not forget why guns were blued in the first place. I imagine that aging and turning plum wasn't a concern back when.

 

[Tyrod]

When Dan Wesson revolvers were first made, they were acclaimed to have some of the best standard bluing on the market. Over time, the bluing turned purple and those revolvers are now called "Barney" guns.

 

[Ben_hutcherson]

In watchmaking, parts are typically blued by heating until they reach the desired color. Deep blue is somewhere in the 550ºF ballpark, but when working up to that color plum to violet appears about 20-30º lower.

Many high end Illinois and Ball watches, as well as a few of the highest grade Walthams, had plum hands instead of the standard deep blue. In fact, for someone who knows where these should be present, seeing blue hands hits you in the face.

In any case, the only gun where I've seen appreciable "purpling" is my model 14. The barrel and cylinder are purple, while the frame is standard S&W blue. I've always assumed that those parts were reblued-in fact rburg was sitting next to me at the gun show when I bought it and I think he was the one who gave me that opinion.

It's interesting that someone above mentioned Model 52s being susceptible. Mine is a late 70s model and I bought it new in box, unfired outside the factory. I haven't shot it much. I'll have to look at it again(I haven't had it out in a while) but I recall it being a nice, rich blue color.