filler

I have a black vehicle that had a quarter panel repainted. Even though I've waited 3 mos.,it is still softer than factory. I find I am polishing out fine scratches more often than I am the factory paint. I also know that the repaint is thiner than factory and that I will eventually polish away the paint. So what I would like to do is just apply a filler to this area. Meguiar's M66 works just fine by hand or DA, but I understand it is a little harsh. I have read that Poor Boys Black Hole or Autoglym Ultra Deep Shine will work, but I would like to get you guy's opinions.
Thanks

Only way to go in my book is to use Glare Micro Finish and then Pro Polish or Infinity. you'll thicken the paint up (using DA at speed 1), and get the best clarity, depth, wetness and colour burst
great protection too.

First of all you are making some assumptions that may not be true. Factory paint is usually thinner than aftermarket.

The typical assembly line paint process is an E-coat on the bare metal which is very thin, probably not even a mil. Then a primer coat which can be 1 to 2 mils; the color-coat (base-coat) which is about .95 to 1.0 mils and then the clear which is 1.5 mils maximum.

Was the area you are speaking of repaired and repainted or was new metal put on the car (fender; hood, door, etc)? If it was repainted then it was sanded, primed, base-coated and then clear-coated. Done by hand there is often much more film put on the car than in the factory. Sometimes intentionally as mentioned on another post because the painter is going to wet/dry sand to remove orange peel. (up to 2.75 mils of clear).

The two-part, thermal-curing paint used in the factory has to be heated to over 300 degress F to cure so it is completely cured when you get the car. An aftermarket paint can only be baked to maybe 140 degrees (they do not use thermal curing paint systems) and takes 60 to 90 days to cure, that is, for all the solvents to evaporate.

However, you can compound an aftermarket paint as soon as it dries and can polish after only a few hours. BUT, you do not want to seal an aftermarket paint with wax, silicone, etc for 60 to 90 days to allow the solvent to evaporate. If you do you can experience "solvent popping."

If you really think that your paint is too soft then you should take it back to the shop that painted it and have them do something about it.

They could have used the wrong solvent for your climate, humidity, etc. Or just rushed the job using a cheap solvent.

Maybe you started buffing on it too soon?

Regards