having a problem blending...(paint question)
 

ok so i got really bored and attacked the rust on my subaru and i got all the major parts that i want and i managed to get lucky and get a shade of white that matched perfectly to the shade of the car but i've run into a problem...

when i am trying to sand it down some, get rid of the over spray and try to blend in the area to the rest of the paint theres always a gap and the color of the paint goes from being the same color to a dirty grey look, whats up with that?
so far its only happened on 2 spots, the others are fine but its irritating because they are the biggest spots, right above the driver on the roof so of course you see it every time you get in.

You're trying to blend rust?

What grit sand paper are you using? To feather, you should be using something in the range of 100-200 grit.

even then theres still a big gap between the new paint and the old paint that you can see.

and no i am trying to blend the new paint into the old paint, its the same color but you can see where the spot stops of course and the new paint begins after i knock the over spray off with some 400.

i realized the greying is comming from the sand paper it self (the things you realize when your sitting on the throne) so i'm going to go to the store and try and get some non colored stuff for wood and see if that makes a difference. the automotive stuff isnt colored persay but its dar grey and the car is white and its probally leaving some behind causeing the greying.

as a side thought if the paint hasnt cured enough could it cause both of these problems?
its been a few days

build it up with bondo or any body filler if you have to

are you wet sanding?

i fail to see how that has any thing to do with blending paint

yep, wet

i've not had this problem on any other car i have touched up spots on, its werid. but this is the first white car so that might explain the greying part but the blending stuff is something different

edit:
just sanded down to primer and re sprayed, area got a little bigger this time. i can start over from scratch

If you cut down a painted area to bare metal, you have to build it back up to match the level of the layers of primer / paint around it.

FYI... just sanding a circle into a panel will make it very complicated to match back up w/ the rest of the panel. Blending usually entails bringing the work to the edge of the panel (unless you don't care how it looks).

oh no i meant the primer from the areas i had to fill so it was level.

i'm not going to bust my rump over it i've come to the conclusion is just the paint thats on it now its all funky any way and is causing the problem so i am just going to hit it with some 1000 wet and then buff it

besides i am just fixing some spots before i sell it