This has not been mentioned yet:
>>> Blending Solvent <<<
Blending solvent is a mixture of solvent and clear which will "melt" into the overspray. It is used AFTER you are done clear coat. When I first started painting cars a decade ago I had no idea such a thing existed. I would always make the patch area too big and try and sand/feather it in. This method does work... to decent results but no where near what an auto body shop will give you. With blending solvent it will be like it never happened. Plus you have half the sanding to do because like I mentioned it melts into the over spray.
Also, if your car is metallic coat you MUST wet sand. MUST. The main idea of wet sanding is to color match any ways. God bless 3m Imperial wet/dry sand paper. Its the cats ass. Serious its the best sand paper I have ever used. Bust out the garden hose and keep er good and wet while sanding. There is no way in hell you will color match w/out wet sanding even if the paint on the car, and in the can are EXACT. Its not so much the COLOR is different, its that the metallic flakes are not... for lack of better words lined up the same as all the other ones on the car. So when the sun glints off the flakes on an poorly sanded panel it sticks out like a sore thumb. Also, do NOT sand in circles for the top coat. It will look like a Zebra if you sand in circles. Sand only in one direction, nine out of ten times with the LENGTH of the pannel. Metallics have a mild learning curve vs solids.
This wont be your issue because your panels are bolted on the car already but its a neat tidbit. Gravity also plays a small role in color matching with metallics. Paint should be sprayed onto panels the same way they will be orientated on the car, its all how the metallic particles "settle". So for example, dont lay a fender flat to paint it. Paint it in the up right position as it would be bolted to the car, this will make it match the OTHER cars panels better. Were talking like fractions of a shade here though... more of a thing you worry about when doing say a body off restoration of a fine collectors car. Just a neat tidbit. I have painted panels before, from the SAME batch of paint on the SAME day maybe an hour later and once done, its like... wtf its a shade off! *OOOPS* had the panel orientated wrong when sprayed.
However, it is also true that not all so called body matched paints match. I have as well picked up a couple spray balms before that were so far off its not funny. And these were not faded cars, maybe 2-3 yrs old. Honestly though... thats happened like 3-5 times in 10 years. Technique Technique Technique!
As mentioned before by previous posters, once its clear coated it will get a bit darker in color. What ya can do is let your patch dry and then flood it with a garden hose. Aka "temporary garden hose clear coat" hehe. Thatll let ya know what it will look like clear coated.
P.S. Spraying quickly at a shorter distance is better than spraying slow at a further distance. Less overspray. I know I know the can says hold it a foot away... ignore that unless you like overspray. Practice on something first though of course to fine tune speed/distance. I like about 6" away. But thats just me, everyone is different. Its what gets the best results for that person right.
Oh yea P.P.S get some turtle wax rubbing compound. Go nuts with that stuff on the area to fix, it will remove old broken down worn out paint that will cause your patch to not adhere very well and chip/peel/flake easy. I suppose you could just hit the area with some sand paper... but why when you can just use compound. Why take off more paint than is really required, I myself would not.
Uhm thats bout all I can think of right now with a few beers in me already
Have good painting! Good luck! Once you master painting its an awesome feeling.
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