Blending in multi-finish and paint blistering

[NickB_99]

Hi all,

Done a bit or patching-in in my conservatory.
I thought I had applied pva well around the area to be blended in - an emulsioned wall over plasterboard/skim. This was done before skimming/feathering out.
For the first time I've seen it, when I then painted with a roller, it caused some blistering of the thin skim over the emulsioned area.
I've had to apply easi fill to repair the bits pulled away and touch up carefully with a brush.
Is this common place when blending in skim and re painting, or have I just been unlucky?

 

[ree]

You have a wall in a conservatory - which wall?

A masonry or stud wall?

This wall had plasterboard fixed to its surface?

The plaster board was previously skimmed?

The skim coating was painted with emulsion?

You skimmed a patch in the existing skim coat?

First you PVA'd?

Then you skim patched, feathering to nothing?

Then you rolled the feathered patch with emulsion paint?

Am i on the right track?

 

[NickB_99]

You have a wall in a conservatory - which wall?

A masonry or stud wall?

This wall had plasterboard fixed to its surface?

The plaster board was previously skimmed?

The skim coating was painted with emulsion?

You skimmed a patch in the existing skim coat?

First you PVA'd?

Then you skim patched, feathering to nothing?

Then you rolled the feathered patch with emulsion paint?

Am i on the right track?

Hi Ree.
Yes, you are on the right track.
Wall is masonry, was part of the original external wall into garage.
Plasterboard had been dot and dabbed onto the brickwork and painted with emulsion, quite a few times along the way by the look of it.
Electrical work had been done at the top, and bottom around a switch, so I needed to repair the original.
Brought back to the original level with bonding, applied scrim over the join. Pva applied to bonding patch and surrounding area, skimmed when tacky. Skim feathered to nothing.
The only parts that suffered were where the skim was feathered very thin
over the original.

I am wondering if it was due to not enough pva, it had dried, or just the fact it is a thin layer of plaster. I'd not seen the problem before.

 

[ree]

Patching skim on p/b i would rule off a squared area, then i would cut into the ruled lines just nicking the p/b, and then prise or scrape off the skim inside the patch.

You will now have straight edges to patch skim to.

First coat of PVA allow to dry, and second coat of PVA allow to go tacky, and then skim. Typically, you should thoroughly wet down, and keep wet, the outside rim of the patch so that the skim doesn't take there.

In your case of feathering to nothing i would have to see a pic before commenting but FWIW it sounds like you didn't go at it while the PVA was tacky.

Personally, i'd avoid feathering to nothing with plaster - its not paint - because of a tendency to de-laminate.

From what i can gather, scrim would not be needed in your case.