acrylic primer undercoat as mist coat

I've removed a failed mist coat from my bedroom walls so I've been reading different forums on what's the best way to paint bare plaster and a lot of people said to give the bare plaster a coat of acrylic primer undercoat before the chosen colour but is this the best method as some people said to use contract matt and others said use retail matt.

 

What do you mean by "a failed mist coat"?

From time to time, I will use acrylic primer when touching in filler that I have just sanded back over the "mist coat" on new plaster (and invariably sanded through the mist coat). In most cases I would still have some of the dilute emulsion left but when I don't, rather than diluting more emulsion, I just use full fat acrylic primer.

The term "mist coat" is rather contentious. Some people prefer to go for a 50/50 mix. I find that kind of ratio to be so thin that the paint splashes all over the place. I follow the manufacturers advice with regards to thinning the first coat- in the case of Dulux Trade paints, that is normally 10% water to 90% paint.

I am not a fan of using contract paint as a base coat, I have had issues when applying the final coats of emulsion in the past. If the plastering is going to require a shed load of sanding/filling/sanding/filling/sanding then I will often use dilute white Dulux Trade matt emulsion- largely because of the "relatively" low cost (compared to the mixed colours). If the plastering is to a high standard I will simply dulte the paint as per the manufacturers instructions- that said, I recently had the misfortune of using a Valspar paint which said that it should not be diluted. I used DT white matt as the dilute coat and then applied a full fat coat of the DT white matt to achieve a constant level of suction prior to applying the valspar.

 

I generally just use diluted white paint as a mist coat (I was taught no more than 40 % dilution but I find that too watery and sprays everywhere so I use between 20 and 30%)

How did you remove a failed mist coat btw and what was used?

 

On some walls there were small patches of paint that cracked like it's been painted over pva so if you took a combination shavehook and scraped the cracked paint you could see the whole wall looked like the paint was dry and flaky and sitting on the plaster. I have a few old tins of emulsion and most says add 10% water or use a plaster sealer but the cheap wilko emulsion says 1 water 4 paint. The walls are not in that good condition and using the top coat watered down will work out expensive to seal the walls so a base coat would be best.

One wall I used wet and dry sandpaper and a washing up sponge and the paint just washed off. The other walls i used wilko paint stripper to get the top layer of paint off then I used the cheap wilko green scotch brite pads.