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-   -   Scope lens internal "smudges" (https://www.rimfirecentral.com/forums/showthread.php?t=1223071)

TRG3 05-09-2021 05:30 PM

Scope lens internal "smudges"
 
I picked up a Weaver K4-C3 scope at a yard sale for $4.00. When viewed through the rear lens, the area around the crosshairs is clear; however, there are what appears to be some "smudges" on the inside of the front lens which appear as slight blurs when looking through the scope. Is there any way to remove these "smudges" without removing the front lens? While there's a little surface rust on the body of the scope, everything seems to be in working order.

Mr Fishhead 05-09-2021 06:27 PM

If the "smudges" are on the inside of the lens, no it cant be cleaned with out disassembly. Clean the outside of the lenses to make sure the smudges aren't on the outside.
If the smudges look like spiderwebs, tiny bubbles or a rainbow, it is probably more than something that will wipe off with a cleaning.

Dan

Al the Infidel 05-09-2021 10:36 PM

I suspect mold if the scope is a pre nitrogen purging era model. I had it on 2 older 4X Weavers from post WWII. I offed em mounted with flip-off side mounts on a pair of Savage 300 & 303 94s.
You could clean yours and purge the internals with nitrogen.

eflyguy 05-10-2021 02:03 AM

How does one "nitrogen purge" at home?

Al the Infidel 05-10-2021 08:24 AM

There's lots of google and utube info for doing it at home.
MGT
Quote:
Originally Posted by berg View Post
I have to open up a couple scopes for cleaning and I don't have a nitrogen chamber or whatever they use at the factory to purge out oxygen. What can I do to introduce the least amount of oxygen back into the scope when I reassemble it?

Also, what is the greasy substance that is used to coat the inside of scope bodies and the threads?
This has been discussed before. It is the moist air that you don't want in the riflescope, rather than oxygen. In a nut shell, you need.

1. Plastic bag
2. Nitrogen supply (a great source moisture free source)
3. Some sort of vacuum pump
4. hoses to connect vacuum pump and nitrogen to bag.

The idea is to place the scope, opened, inside the bag and vacuum out the air. Then fill with Nitrogen. Repeat process several times, until you are satisfied that all moisture has been removed. If memory serves, Burris advertises that they repeat this Nitrogen purge process 25 times. Then while scope is inside bag, at low enough pressure that you can grab various parts, like front objective lens carriage, seal it up.

eflyguy 05-10-2021 09:11 AM

I think it would be cheaper to buy another scope! :rolleyes:

TRG3 05-10-2021 01:18 PM

Quote:

Originally Posted by Al the Infidel (Post 12312303)
I suspect mold if the scope is a pre nitrogen purging era model. I had it on 2 older 4X Weavers from post WWII. I offed em mounted with flip-off side mounts on a pair of Savage 300 & 303 94s.
You could clean yours and purge the internals with nitrogen.

It does look a lot like mold. While it is bothersome, I think I'll just leave it alone and concentrate on the crosshair area which is still clear. On another scope, I contacted the company that bought out Weaver and they wanted a minimum of $95 to fix any scope, more than I was willing to pay. I remember when the original
Weaver company would repair their scopes for free. Ah...the good 'ol days!

Etpm 05-10-2021 07:16 PM

The refractive index of argon is very close to that of nitrogen. Nitrogen must be used as a purge gas because it is so abundant in our air, since our air is about 80% nitrogen. Argon however is very common in weld shops. I have 3 large cylinders in my shop and welding is just a small part of my business. You could remove the lenses in question, clean the fungus from them if possible, and then put the scope with the lenses removed into a large Ziploc bag. Take it to a local welder and have the bag inflated. Let it sit for a few days to let the gasses mingle completely, take it to the welder again, squeeze the gasses out, and have the bag filled again with argon. Do this a few times and then screw the lens back in, keeping all parts in the bag. In order to make this worthwhile the lens cells must be sealed. The whole scope must be able to be a sealed unit. And looking online will provide the info for removing fungus from optics. If someone came to me at my shop I would not hesitate to fill several gallon sized bags with argon just to see if the experiment worked as planned. Argon used for welding is at least as dry as nitrogen used for putting.

JGP 05-10-2021 08:44 PM

Never tried this but how about cleaning the scope, put the parts in a clear plastic bag with a few desiccant packets. Leave it for a few days then reassemble without un sealing the bag? Just me thinking

Al the Infidel 05-11-2021 07:44 AM

Quote:

Originally Posted by JGP (Post 12313395)
Never tried this but how about cleaning the scope, put the parts in a clear plastic bag with a few desiccant packets. Leave it for a few days then reassemble without un sealing the bag? Just me thinking

The easiest and good for another 10-20yrs., maybe eh?


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