my apologies if this is in the wrong area; what type of paint markers do you guys use to index screws? I’ve been using a silver sharpie, but I think this is less-than ideal, as its very difficult to remove.
I see a lot of guys using a red one, is it something like this?
http://www.sharpie.com/enUS/ProductCategory/paint_markers.html
water based, or oil?
links to products are greatly appreciated.
Sincerely,
Tom
I use black.
Forney welder’s silver paint… sticks good, gun solvent doesnt wash it off, wont cook off, subdued metallic gray color. i also use it on my selector for an easy reference on weapon condition
i use testor’s enamel paint pens that you get a hobby shops.
The type paint pen I use: uni PAINT Medium Line PX-20
Not sure where these can be purchased at. These came pre-packaged in a service kit that we used, at a former employer. When the job was done, the pens were usually tossed. I kept mine and took them home……just for this purpose, along with IDing new magazines. 
They can be ordered through Staples.
i use a silver sharpie too - i like that it’s difficult to remove. a dot with the tip is all i put, not a line.
I use the girlfriends red fingernail polish…
Good to know now that my supply of free pens has dried up! Thanks. 
to tag along with the original question, where are some key places that one should index mark? i though there were some pictures posted before, i might be confused though.
We actually used fingernail polish in the military. Guys would always get ribbed for having a bottle in their tool box. And, it got you funny looks at the PX check-out lane for sure.
The typical product used in aviation is often referred to as “Torque Seal”.
I have a link posted above in my first response which has pics.
As far as where to apply “slippage marks”, it’s really up to you. Some typical places would be scope ring hardware, BUIS mounting hardware, gas block mounting hardware, any place where it would be desirable to monitor for screw loosening.
Pretty much anywhere there’s a screw, a witness mark can help. For QD optics, can also extend that onto the receiver to keep the place.
I use the some cheap paint pens - Pink and a light green for the most part - it shows up on my krylon jobs well, and the pink is for the wifle.
Thank you everyone for the help.
-Tom
Just clarifying it for you.
Mike
Okie Dokie 
My woman seems to have lost a bottle of her white and gray nail polish. Wonder where it got to??? :rolleyes: Good for thread locking too, doesn’t react to heat.
I’m squared away with the paint pens since my wife is (among other things) an artist, so I’ve got a different question here. How can I safely take the paint off the metal when I no longer need a specific witness line? I need something that preferably is easy and super quick to use and won’t fade or discolor the carbine’s finish on the area around the witness line.
Try Hoppes Semi-auto solvent (blue bottle as opposed to the original orange bottle). It is ammonia based instead of oil based and it takes off just about everything and dries fast. I usually follow up with Miltec or CLP.
i always heard clear was the best thread-locker… dont know why, though.
pretty much anything. lacquer thinner is my all-purpose organic gun-solvent, and it’s totally safe to use on ARs, but you don’t need to go that hard-core. acetone should remove almost as much all by itself. put a dab on a cloth and wipe it right off.