Cracks appearing in paint. Is plaster sealer the answer?

[Iotrez]

Hi all,

I stripped the wallpaper on the walls that I am decorating and used sugar soap to wash them down.

I then filled holes with polyfill and used Polycell smoothover on the rough areas. I then sanded it all down.

Then next stage was to add a coat of polycell base coat for walls.

I then painted a matt colour on top of this from the B&Q colour range with a roller.

The problem is that hairline cracks are appearing on the final coat of paint.

I have tried sanding it down and re applying the paint but the cracks just appear again.

After reading the instructions on the paint again I noticed that it says that if painting directly on plaster, a coat of plaster sealer should be used.

This is a step that I missed out and I think is maybe the reason that the cracks are appearing. Can I now just paint a coat of this plaster sealer on top of the paint that I have already put on the walls? And then put another layer of basecoat followed by the mat paint on top of the plaster sealer?

Or will I have to strip off all the paint I have put on so far?

Thanks for advice.

 

[Third_Eye]

From what stage of coatings is the cracks appearing ?

 

[Iotrez]

I'm not too sure. I think I only noticed them after the 3rd coat, but maybe they didn't have time to develop after the other coats (before the next coat went on.)

 

[Third_Eye]

Is it the matt B&Q emulsion that has cracked ?