How do i fix paint flashing?

Question

So I spent the weekend patching over a paint rip and have finally gotten the wall level after a ton of sanding/mudding/priming the spot etc. I’ve finally gotten a decent color match and gone over the wall with a roller. Problem is, the whole thing looks splotchy and uneven, there’s quite a bit of flashing coming through. I can also see the outlines of the patch shining through…

I used a water based paint and went over the wall using a roller for acrylic paint. I plan to do at least one more coat (maybe two if necessary) but I’m worried the texture just won’t ever become even or smooth enough to pass an inspection. I’ve never painted before and just want to get this over with…
 

I’ve heard that flashing is caused by not maintaining a wet edge while painting but I’m not sure how to remedy that — I try to coat my roller evenly and just go from ceiling to floor in “stripes” but it seems like the paint just inevitably flashes... Any advice (technique or otherwise) to fix up this paint job?

Answer 1

Entire answer found when I was looking up what "paint flashing" means. Relevant part reproduced below:

When a paint flashing problem occurs during a touch-up or full-scale paint job, the best solution is to apply a second coat of paint – applying it from one break to another. This method helps to diminish the noticeable distinction between the new finish and the old. A break in a wall is typically at the corner, but may also occur when trim molding extends from the baseboard to the crown molding. Regardless of the extent of the paint flashing, follow these steps to fix the problem:

1. Start by sanding the surface with extra-fine grain block sandpaper. Sand just enough to even out any areas of thick paint and level out the texture.
2. Using a damp cloth, wipe down the surface to remove any remaining dust from the sanding.
3. Then, clean up the work area using a shop vacuum. Dust particles are very small and easily airborne, which means that are highly susceptible to landing in finish coats. If you don’t have a vacuum, you can sweep, then allow the dust to settle for 15 minutes and sweep a second time.
4. Prepare a new batch of paint by pouring it into a paint tray. Use a high-quality type of paint and don’t dilute it. Diluted or low-quality paint typically goes on unevenly. Also, different pigment concentrations can create flashing.
5. Start applying a fresh coat of paint on the surface. First, dip the roller into the paint and roll it on the tray to get rid of the excess. By doing this, you are preventing the presence of thick and thin layers that create flashing in your finished coat.

As you are painting, work fast and always lead with a wet edge. Paint from one edge of the wall all the way to other and do not join dried sections. Painting over areas that are partially dried will create uneven layers.