Just my thoughts on this and I am NO expert, but if you try to hide, paint over , obscure the marking you MIGHT be setting yourself up for a pain in the ass time later on. Think about this, your at the range shooting your supresser a "concerned citzen" call the local Cop Shop they send a vehical. He gets there you show him your form 4 and when he goes and checks the numbers, the numbers on the can are not CLEARLY marked. You have just popped up on the radar and here comes the ATF. I am not saying that you would get stuffed and cuffed but I do see you in a small room with Barney explaining why YOU chose to try and hide the numbers. Me personnaly I like mine to stand out. Have I been stopped YUP showed him my paperwork gave a quick class on how you get one and guess what another victum of the new age crack better known as the Wonderful World of NFA