doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Sunlight and case colors

Lloyd, I can't equivocate clothes' colors fading in sunlight with case-hardened colors fading. One's colored with dye. The other is not colored with anything. The colors we see on the gun is a prismatic effect. For sunlight to change what the eyes see, on a case-hardened surface, the photon bombardment Ryan speaks of would have to physically change the structural shape of the tiny prisms.

Can that occur? IDK. Basic physics never taught ME that. Heck, as old as I am I'm not even certain photons had been discovered when I last sat through a physics class. 🤣

Stan: what I got out of the wondeful list of old posts here that Dr. Drew provided (wish I could search that effectively here) was that the destructive component of natural light here (i.e. sunlight) was UV. Ultraviolet light is a known force in many processes now (and has been for most of my lifetime). How it exactly diminishes the beauty of bone-charcoal hardened finishes over time still excapes me however.

If it is truly the UV rays in sunlight that can degenerate case colors there could be an easy fix. Automotive clear coat protects paint from the UV rays, and is almost perfectly clear. Yet, I believe there are solvents that will remove it if need be.

However, before I try some I've got to be convinced that this even happens.

Something changes it. Roughly 6-years after purchase this was what my case colors looked like on that Estate BLE...



Now, it wasn't protected in any way that I could tell (no protective coatings, and I wouldn't have expected that on an inexpensive gun) and I didn't expect the colors to not change (old guns look that way for a reason, right?).



Significant change, eh? Now, you can see where I had been carrying the gun on the later picture but it wasn't just me using it that caused such a departure from it's original appearance. It's either a natural degrading of the finish over time or it's caused by environmental issues, or it's both. I certainly didn't abuse it, but neither did I baby it. I merely used it for it's intended purpose.

This happened pretty quickly too (6-years is nothing when you think about it) and I have always stored it nicely cleaned (well, wiped down with a light oil) and upright in my gun cabinet, well away from any real source of UV. Go figure?

Interesting discussion, thought I might share an experience I have had. For the last 27 years I have hosted The Oregon Gunmakers Fair at my shop every spring. The emphasis of the Fair is a number of short seminars on traditional gun making techniques, predominantly centered around the building of flintlock and percussion firearms. Some 20 years ago we invited a professional metallurgist to demonstrate case color hardening. He used 1 1/2” square coupons of mild steel for the demo, and produced some wonderful colors, with attendant hardness. One of those example pieces has resided in a south facing window all this time, with no degradation of color, and no, it has had no coating applied. A sample of one, I know, but I suspect wear is a greater contributor to loss of color.

OTOH, my Dickinson is about 1-2 years older than yours and I cannot tell that the colors have degraded in the least.

Thanks for that information, Warren.

The plot thickens.

Yes it's a know fact the sun bleaches everything on earth but case colors on guns.

This is an interesting topic, and I'm still in agreement with Stan. We simply don't know if sunlight alone can degrade case colors.

As I said earlier, I did a lot of searching and found exactly zero definitive tests done to determine the effect of sunlight. The very limited and informal test supposedly done by Dr. Gaddy would hardly constitute "good science", so it should not be accepted as Gospel by those who demand "good science" in matters of Climate Change, lead poisoning, declining quail populations, etc.

It only involved one small sample. We don't know if the samples had any protective coating such as lacquer, wax, or gun oil. The alleged sample was done with sunlight coming through a window, and we know window glass filters out a lot of the UV spectrum, especially UVB. Nobody hunts under glass or in a greenhouse. And we also know sunlight is composed of a wide spectrum of visible and invisible wavelengths, so there could be something aside from UV alone that MIGHT cause a change.

It involved only one case hardening process and one alloy of steel. So we can't say that different compositions of charcoal, different alloys, or different quenches create the same changes to the molecular structure of steel which we see as case colors. Should such a test be done in an inert gas atmosphere to exclude the effects of air or pollutants? We don't even know how much time was involved in this "test". We would also have to include the degree of surface polishing because we know that highly polished steel resists oxidation better than a rougher surface. The case hardening process is far different than dying cloth or painting a car. Stan is correct when he says that case hardening is not simply adding a pigment or dye to the steel. However, we do know that cooking steel in a crucible with different recipes of bone and wood charcoal for hours at high temperatures does in fact infuse carbon, carbon monoxide, and other compounds a few thousandths of an inch deep into the surface of the steel. This chemically changes the steel near the surface by giving it a higher carbon content than the base metal. But is it just carbon alone, when we know that different charcoal contains many other elements? The quench somehow locks things in place, and the quench itself is often done with different water at different temperatures. This is what somehow creates those "prisms" Stan spoke of, which reflects and refracts light to our eyes in differing hues and colors. So now we get into a realm of molecular and atomic bonds that are difficult to see or understand even with the use of electron microscopes. The quench may be straight rain water, city water, or it may contain additives like potassium nitrate, bat urine, or eye-of-newt. It may be agitated or infused with air bubbles. Most practitioners of the art seem to find that colors are more vibrant if they can exclude as much atmospheric oxygen as possible from the parts while dumping them into the quench. The guys who do great case hardening seem to eventually settle on a process that gives them good results, often through much trial and error. But if they know every detail of the chemistry involved, they certainly aren't sharing that knowledge.

If this thread accomplishes anything, I hope it begins to make people understand that conjecture, thinking, and even wild-assed guessing is OK... so long as it isn't stated as fact. Because as things stand right now, when you do a deep dive into this subject, you will find that books, magazine articles, and the internet is literally filled with so-called experts who state things about case hardening as fact, in their attempt to explain what causes case colors to fade over time. And most of what they are saying has absolutely no basis in proven facts.

So, you believe that sunlight bleaches case colors, like Clorox bleaches dye?

Stan,
Since case colors are the product of a reaction between steel, carbon, and heat, and no two lots of steel, bone or charcoal would be absolutely identical, nor would two quench solutions be absolutely identical, how can we assume wear rates or susceptibility to fade would be identical between different guns from different manufactures at different periods of time?

I read an article that made the point that Baker case colors were considered very durable in the era they were produced.

I have often wondered who came up with that, and how?

Best,
Ted