Birchwood Casey Aluminum Black to fill engraving on anodized lower?

[DS94901]

Posted this in centerfire and realized it probably belongs here instead. I never had the chance to get my lowers engraved before anodizing and I'm wondering if anybody has had any experience with coloring the engraving using something like the Birchwood Casey Aluminum Black. I don't need an exact match to my ano but I don't want raw silver aluminum or to fill it in with any colors. Is this something that will affect the ano color if I accidentally get it outside of the engraved area?

[Twystd1]

That will work ok.

I use it all the time for touching up.

And it won't hurt anything.

-T