block sanding blues

I'm block sanding my scamp, and every where I used spot putty it shows up in the flat black, I'm using 1000 wet dry paper, it's smooth as glass put as soon as the paint hits you can see every spot,](*,) what can I put down to stop these spots from showing up like uninvited inlaws at a bbq:dontknow:
any ideals? thanks mark