New paint flaking - help!

[zaffa]

We are trying to paint a number of walls in a flat - covering previous colour with white. We started with wickes white paint but the paint was quite thin so have switched to dulux white paint for coats three and four and it's all suddenly flaking off! Does anyone know why this could be happening? We did the first two coats with a paint pad and the next two with a large brush (at the same time we switched to dulux paint). Pics below

Is it too hot in the room? Could be excess moisture or a number of things really!

Thanks - the first two coats didn't crack or peel at all though, it's only happened when we switched to a brush and to dulux

Can you link to the exact paints you've used? This might be caused by mixing different paint base types.

Thanks @QueenStromba. This is the dulux https://www.screwfix.com/p/dulux-matt-emulsion-paint-pure-brilliant-white-10ltr/1013V?tc=VT2&dskid=92700052136101329&dssrl=1243321&dsrl=1241687&dssrl=1245250&dsrl=1245250&gclid=CjwKCAjw9r-DBhBxEiwA9qYUpQNTXz6nsirJC6sGTURaw9ZIQBfDJugBkBP5xnhHFqqi70q8gY0fxxoCluIQAvDDBwE&gclsrc=aw.ds and this is the wickes https://www.wickes.co.uk/Wickes-Matt-Emulsion---White-10L/p/145119?utmsource=google&utmmmedium=cpc&adpos=&scid=scplp145119&scintid=145119&gclid=CjwKCAjw9r-DBhBxEiwA9qYUpdUcULP9o27rQI86t9vPvGtHZLztq7NodpAS9mEV3BBIYGKA04WUbRoCTwUQAvDBwE&gclsrc=aw.ds as far as we could tel they were both white emulsions. The paint is peeling along the brush strokes it looks like

A lot of the reviews of the Wickes paint mention a chalky residue - I think that could be your problem. That or you've not left it to dry properly between coats.

Did you clean with sugar soap first?

Is the paint flaking back to the original plaster?

Is it a new paint brush? Could there be some kind of chemical residue on the brush your using? How did you prep the wall before? How long are you leaving it between coats?

Thanks all. Did one coat per day, so painted in the morning and came back the following morning to continue. Paint brushes all new - their first use was for the dulux paint. Same with the pads we used to put on the wickes paint. It's peeling back to the wickes paint, not the coats before this (walls previously painted with a different matte emulsion many years ago - we have the tins to check). Walls all washed down with sugar soap before starting.

Didn't think of the chalky finish - I had thought this would be caused by something like a silk paint rather than a chalk finish

Bumping hopefully - we aren't sure what's caused it so don't know how to proceed

I do think it's probably the chalkyness of the Wickes paint - anything powdery like that will stop the next layer adhering properly. You need to scrape off the flaking paint, give the whole surface a light sand and clean with sugar soap.