I have a problem which is really giving me headaches.

Recently I set out to cover some repairs that had been made to a render wall. A match was found for the original paint but on application was shade darker, this can happen with a particular brand of paint so it was decided to paint all the walls in the room. After the first application there was inconsistent coverage from a roller so a second coat was applied which has lighter coloured patches only really visible in subdued light but not in bright daylight so the wall was painted again this time with a high quality brush and some of the patches are visible again. These patches are in the same place so it is not inconsistency of coverage as particular attention was paid to the patches and fresh paint was used for each coat


Any thoughts

These patches where its lighter, its not because of a difference in texture at those spots that can make it appear lighter?. and before being painted, there wasn't a spot there of a significant difference in color, that may take numerous coats to hide? I had that issue when painting a wall that was patched, sanded and spot primed but the primer was white , the walls were originally Antique white (which is really a crappy light tan/gold color) and I had painted them an off white as I hate antique white with an absolute passion. Took a few coats to even that out...Next room I primed ENTIRE walls before painting top coats to avoid it.

My first thought: lousy brand of paint. The best brands don't do that.
Second thought: were the inconsistent patches just over the places where you did repairs? That can do it.

Other thoughts are about the material the wall is made of and the kind of roller you are using, the material, thickness, and type of nap.

Was a primer used prior to painting over the existing paint?

No the wall may have been painted many times when I bought the house it was yellow I upgraded the paint about five years ago to a light grey which looks blue. The paint I have used which is top quality covers the repairs well and I used a high quality brush after roller on the first coat was unsatisfactory, but unfortunately dried darker. The patchs arnt near the repairs. Im wondering if its something associated with the render

See my post to j9