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Discussion Starter · #1 ·
Other than old age.

Is there material in there that can leak out? This is a Sig night sight.

Long story short, Sig checked the sights for accuracy on my 226 and as far as I know made an adjustment. But when I got it back the front sight is dead, no illumination, and it light up like a Xmas tree before. Sig CS confirmed the sight wasn't swapped for an old one or anything like that. If he's right, how could it lose its illumination?

They're sending me a new one in the mail btw. Gonna have it installed locally.
 

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Night sights have tritium. The tritium in a gaseous tritium light source undergoes beta decay, releasing electrons which cause the phosphor layer to fluoresce.

During manufacture, a length of borosilicate glass tube which has had the inside surface coated with a phosphor-containing material is filled with the radioactive tritium. Tritium half life is about 12.5 years. This means as time goes on, they will get weaker and weaker. After a certain period, the sights would need to be replaced.
 

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Sig, Meprolight and Trijicon all use Tritium gas which is a very expensive form of hydrogen. It dies a normal death because the half-life of tritium is roughly 12 years. Tritium is a beta particle emitter that decays to helium which will not illuminate your sights.

Only the US government and the USSR produced tritium to produce thermonuclear weapons in the megaton range. US production was at Savannah River, but SR has stopped producing. The US has sold small amounts of tritium for reasons that are unknown to me.

Hydrogen is an extremely small gas molecule that is diatomic. It leaks if given the slightest opportunity. It seems to be epoxied into a small glass-like module that reacts to the beta particle (electron) by producing a faint light. If the gas leaks due to damage to the sight, the light goes out quickly.

Since tritium has a half-life, the sight manufacturer date codes the sight. Sig factory sights seem to be Meprolights. You will need a magnifying glass and a means of deciphering the date code if you want to know how old the sights are.

Bill
 

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One hard hit and the tritium can leak out. One of my shooting buddies had night sights put on by a local gunsmith and they broke the front sight during installation and didn't mention it to him, when he took it home the front sight was dead. He never went back to that guy again.
 

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Discussion Starter · #6 ·
You guys rock!

Yup def clean, just cleaned it last night, nothing obstructing it. The 226 has a born on date of Nov 2012 and it worked fine before, so...sounds like it got wacked at Sig.

Is it somewhat fragile to begin with? Do you clean with caution? I've always cleaned my whole slide with a towel and brush, spray cleaner all over it with no problems.
 

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Who knew I would be signing up for science class when I checked this thread! Neat stuff.
Familyguy, in my experience, it would take a much heavier knock than your bruch or towel to jar them loose. I brush the living **** out of my slides with a nylon brush when I'm cleaning with no issues. Think maybe yours got caught in the rest or something similar when it was at Sig? Could also have been fat-handed at Fed-ex. They aren't known as the most cautious shippers. Hope you can get that new one on with no more alignment issues!


Whisked to you by a cloud of fairy dust
 

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Discussion Starter · #8 ·
^^

Cool, I brush the hell out of mine too when cleaning :)


Yeah, it must've gotten wacked at Sig while setting the sights, or maybe during shipping. The rears are fine, so most likely a direct hit to the front while setting than overall shock to the whole slide while shipping. Oh well, new one coming in under warranty. I think this mystery's solved.
 
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