Why yes as a matter of fact it is. 12895. White tolex with a black grill cloth. No reverb no GEQ, EVM12 and as close to mint as I have seen. A true closet amp. I went with a friend of mine in Chicago to check this amp out from an ad in the Tradin Times. He bought it for 600 dollars about 18+ years ago. Sounded great then and still sounds great today. I bought this off of him for a hefty increase in price but this has been babied ever since he bought it, never gigged with. A rare find these days.
I have never seen that marking before, wonder if it meant anything.
Looks like nail polish. You ,ay want to call Mesa with the serial # and see if they have any RA's on it.
If something was done post 1990 or so, they will have a record of it.
It's does look like nail polish now that you mention it. I will call on Monday and see if I can find out anything. Not a big deal but would be interesting to know what it was about. Thanks.