That's precisely what I was concerned about. Thanks for the link. Great website, by the way. Where do you buy selenic acid? Or do you use some product based on it? Thanks.Raw brass reacts with wet leather. If the leather is wet, the deterioration can be fast.
carolus;3809726Where do you buy selenic acid? Or do you use some product based on it? Thanks.[/QUOTE said:This Birchwood Casey bluing pen is what you can find at sporting goods stores that sell fire arms. Here is a video showing how it works on steel.
https://www.youtube.com/watch?v=TtDt89VZleg
In the video, the bluing pen appears to turn steel black rather than "bluing." The black film tends to lighten up when cleaned with gun oil and leaves more of a blue tone (on steel). The alloy and the acid determine the effect, that's why some use steel bluing concoctions made of a variety of acids. The same is true with turning brass different shades. Since the color isn't important on a brass tone hole rim, the mixture in the bluing pen works for creating a corrosion resistant finish. With the cap back on the pen, it is good for years (and other projects).
Some may never see rust on needle springs, or not care. If you do want to refinish the bluing, this is the pen for you. Some may also never notice the effect of raw brass on leather, but if you look closely, you can see that there will always be a reaction. It's just a matter of time and moisture (and maybe magnification). The pictures in the first blog showing this reaction are not rare by any means. The pictures just show an obvious case on a mid-50's Conn. Here is a recent blog on a mid-60's tenor rebuild that shows the same condition on every tone hole rim (plus a nice photo of an Eb pad that played a little stuffy, but I decided to replace as part of the rebuild).
https://stuffsax.blogspot.com/2018/11/1965-beaugniervito-tenor-rebuild.html
In other blogs, I used acids to change the patina on the entire brass saxophone and the bluing pen to blue the steel hinge rods during a rebuild. Neither are "necessary," but I'm rebuilding saxophones with the intention of long-term personal use, so I do it. It just takes a minute.
Mark
Question: the bluing as I understand it is primarily a result of thermal treatment of steel - hardening and tempering - but you are strictly talking about chemical treatment here to restore the looks and prevent corrosion?Those are some very interesting "outside of the box" ideas. I have never heard of bluing hinge rods for example. A method I like to use on springs is similar to what you have described. On vintage saxes with rusty springs that are otherwise in good condition, I first remove the rust using 0000 steel wool which also removes any remaining "blued steel" color. Next I use gun bluing sold in small bottles at sporting goods stores applied to the spring using a Q-tip and wait for it to dry completely for about 5 minutes. This gives the raw steel a blue color, but it is a very flat, dull finish. Next I apply a layer of Renaissance Wax which dries almost instantly. That is then rubbed to a shine with a soft cloth and the old rusted spring looks like a shiny new blued steel spring again.
I think two different ways of producing a thin layer of black iron oxide, Fe304. I don't know why it's any more resistant to oxidation other than I guess it's already oxidized...Question: the bluing as I understand it is primarily a result of thermal treatment of steel - hardening and tempering - but you are strictly talking about chemical treatment here to restore the looks and prevent corrosion?
Thanks!
The liquid cold blueing agents we are talking about here are typically applying a selenium dioxide compound. Its not really the same as the hot blueing process and is really just for cosmetic touchup in most cases (on steel).Question: the bluing as I understand it is primarily a result of thermal treatment of steel - hardening and tempering - but you are strictly talking about chemical treatment here to restore the looks and prevent corrosion?
Thanks!
Thanks, if I remember, the color change resulting from tempering is not as much a chemical reaction but a temperature-dependent change in displacement of carbon within the iron/steel (at least that's what I was taught many decades ago - and there is some oxidation going on of course).The liquid cold blueing agents we are talking about here are typically applying a selenium dioxide compound. Its not really the same as the hot blueing process and is really just for cosmetic touchup in most cases (on steel).
But if it works for this application who am I to judge.
That video was freaking me out too!
Been a while since I pretended to be a metallurgist but I seem to remember that the "hot" bluing (used by gunsmiths among others) is a straight chemical reaction with the salts in the dip mix at elevated temperatures to create a passive (ish) oxide coating. There are also colour effects seen just as a result of heat treatment building a thin oxide layer on steel that has some sort of interference effect that alters the colour if I remember right. Probably a ton of info out there for those that want to google it, I suspect none of its rocket science.Thanks, if I remember, the color change resulting from tempering is not as much a chemical reaction but a temperature-dependent change in displacement of carbon within the iron/steel (at least that's what I was taught many decades ago - and there is some oxidation going on of course).
I was just curious, there are so many ways of doing things different now, hard to keep up.
Yes.It is a non issue in my experience. Of more concern after leveling toneholes is to remove any burrs around the edges.
Yes. It is designed to mislead. And no decent technician would remove that much medal from a tone hole. Most of tone hole levelling is completing what the factory did not do properly.The above video freaked me out until I saw that it was a video loop. The horn looked to be ruined and yet the culprit continued? The stuff of nightmares.
I don't totally agree. My 50 years of observations suggest that this happens very readily with some pads (even within months of brand new) but not others. I therefore tend to think that substandard pads use a leather where the corrosive tanning compounds have not been fully removed/neutralised. Use respected brands, high quality pads.... Raw brass reacts with wet leather. If the leather is wet, the deterioration can be fast... It will produce "little chunks of stuff" (my scientific terminology) that will stick in the pad seats...
Heck. I once had an (expensive/) can of pure tung oil. It sure polymerised, within about 10 years - faster for the spillos outside the can - into a sticky substance resembling half-set varnish. I would not want that anywhere near my pads.... I've tried a couple of things to seal the raw brass. Wiping with tung oil works, but it take the tung oil more than a week to polymerize (solidify or "dry"), which is a pain to wait during a repad...
I totally agree.It is a non issue in my experience. If the tonehole is cleaned occasionally with naptha, and/or a few passes of 1000 grit sandpaper, the bare brass will not be a problem. Of more concern after leveling toneholes is to remove any burrs around the edges.
I certainly would not allow a strong acid (from a bluing pen) to seep into the mounting of a needle spring. at the very least, I'd expect the resulting galvanic corrosion to eat away at the metal.... Some may never see rust on needle springs, or not care. If you do want to refinish the bluing, this is the pen for you... In other blogs, I used ... the bluing pen to blue the steel hinge rods during a rebuild. Neither are "necessary,"
I'm interested in a source for this information.The liquid cold blueing agents we are talking about here are typically applying a selenium dioxide compound...
I found this on a question and answer page. I cannot vouch for its accuracy, but it seems to make sense. "Liquid gun blue is a two step process, the first deposits a very thin copper layer from copper sulfate (the blue color ) and the copper is immediately turned black by the selenium in the solution. It must have free iron on the surface for the copper and the iron to swap so the copper plates onto the iron."According to the MSDS sheet for the blueing pen - https://birchwoodcasey.com/files/datasheets/13201-Presto-Gun-Blue-Pen.pdf - the pen contains selenious acid, cupric sulphate and phosphoric acid. But I have no idea what that spsecifically does to steel, let alone brass.