Update:
I got a reply from a Vortex Optics sales and technical (support?) representative. In my query I also sent a photo of the objective lens in question. I didn’t mention anything about caked on mud, but I’m glad he mentioned it considering that I have slipped and fallen while carrying a rifle in the woods. His advice is as follows:
“I am happy to give you some pointers regarding cleaning your lenses.
Caked on mud can certainly be a challenge when cleaning lenses. First things first, here is a list of recommended tools and solvents to use:
Nylon brush style lens pen
Ordinary cotton Qtips
Wooden toothpick
Canned or preferably compressed air
Water
60 to 90% Isopropyl Alcohol
Liquid lens cleaner solution
Paper towel
The key to this is really going to be technique more than anything, so I apologize if some of this sounds rudimentary or redundant. First thing I do is blow away and loose debris with some strong compressed air, preferably from a hose. The next thing I do is kind of try to break up any harder stuck on pieces with the nylon brush end of a lens pen. I will kind of poke at the crust and try to flick it out as I do, rotating the entire bino around the lens pen. Periodically I will turn the bino upside down and let the debris fall off the lens as I pick and flick the mud. I focus on the rim of the lens mostly. If there is still stubborn dirt after this you can go after it very carefully with a wooden toothpick, try to poke very intentionally, do not drap the pick across the glass. Continually keep picking and flicking with the nylon brush to remove any loose material as well as blasting with compressed air as you go.
Eventually you should get to the point where you pretty much only have a dusty kind of surface left. When you get to that point, soak the paper towel in water and lay it very carefully on the lens itself to try and soften up the dust. Make sure not to scrub with the paper towel, try to avoid rubbing the glass until you get to the q tips. Soak the q tips in water and very carefully wipe from side to side the lens. Go slowly and do not use alot of pressure. It should almost feel like you are doing a charcoal or pencil rubbing over a plaque or something like that. Continue to let is dry and hit it again with the brush and air. After that, go after it with the same process just with the alcohol on the qtip instead. Repeat again with the lens cleaner. After you hit the lens with the cleaner, go ahead and blow some hot moist breath on the lens to fog it up and clean it with the felt pad end of your lens pen and that should do it.
Do not use any solvents other than the alcohol and remember not to rub the lens until all the dust and dirt has been removed.
It's very difficult to really express the best way to clean them without having a lot of experience, and plenty of screw ups along the way.
As always, if you don't feel comfortable cleaning the lenses, we can always help you out and do that for you. Just let us know.”
What
@Convex communicated about technique in some of his responses is echoed above. I’ll probably give it a shot by this weekend. I also like the tip about carrying a few wipes in my pocket on a hunt. I’d been leaving them in the carrying case. Thanks again you guys.