I'm not sure what I should be doing to remove these. I have a coat of Polish Angel Master Sealant currently. When I washed the car earlier today I noticed a few black particles on the rear of the car that washing didn't remove. I sprayed some ironx on them and then very lightly dislodged them with my fingernail, then rinsed. It wasn't iron so ironx didn't do much to dissolve them. They were bonded enough that washing with a Microfibre mit didn't lift them off but not enough to require clay. I didn't really want to clay as I thought it may strip the sealant. How I do get these off in future without compromising the sealant?