Painting new plaster

[Gossamer]

Hi a few months ago I had a few ceilings boarded and skimmed.
I left them about 10 days then mist coated with supermatt at 3 parts paint, 1 water as recommended. I then painted with 2 coats at 5:1.
This week I removed some masking tape from a ceiling after painting and some paint came of in places around the edges down to the plaster.
Now I'm bricking it I've done something wrong as I thought the mist coat bonded with the plaster, not just stuck to it.
Is this normal when removing tape from ceilings?

 

[phatboy]

It's not unusual, I would never stick tape to anything other than oil or masonry paint in case this happened.

I doubt your preparation of the new plaster was incorrect, it sounds fine.

 

[Gossamer]

Cheers.
Was just a shock as I thought the point of a mist coat was to strongly bond with the new plaster.
I've brought some orange Frogtape now...

 

[chris_o]

Where did you bring it from?

 

[phatboy]

Where did you bring it from?

The DIY shop I imagine. Now where is my troll spray....

 

[stevethespreader]

Hi a few months ago I had a few ceilings boarded and skimmed.
I left them about 10 days then mist coated with supermatt at 3 parts paint, 1 water as recommended. I then painted with 2 coats at 5:1.
This week I removed some masking tape from a ceiling after painting and some paint came of in places around the edges down to the plaster.
Now I'm bricking it I've done something wrong as I thought the mist coat bonded with the plaster, not just stuck to it.
Is this normal when removing tape from ceilings?

How long did you leave the tape on for?

 

[Doggit]

A mist coat should really be 50:50; it's designed to be wet enough to soak into the plaster, and bond in any dust on the surface at the same time. You may be okay, as a lot of tapes that get left on too long, stick like sh1t, but only time will tell I'm afraid.

 

[Gossamer]

How long did you leave the tape on for?

Maybe a week. Probably too long in hindsight.

 

[Gossamer]

A mist coat should really be 50:50; it's designed to be wet enough to soak into the plaster, and bond in any dust on the surface at the same time. You may be okay, as a lot of tapes that get left on too long, stick like sh1t, but only time will tell I'm afraid.

I did ask the plasterer and suggested 50/50 but he said 70/30 max. In the end I followed Dulux's advice and went for 75/25 (3:1) in the end.

 

[phatboy]

I would never go 50/50, seems way too thin. Normaly 80/20 or 70/30 depending on the paint

 

[stevethespreader]

weve had this debate for ages about mist coats 50/50 snag if needed then 50/50 if the walls are porous and you havent watered it down enough it will literally dry out to quick in some cases the moment its left the roller , but i dont think that was your problem i think you left the tape on to long

 

[Doggit]

Normaly 80/20 or 70/30 depending on the paint

This is where the novices go wrong. The purpose of a mist coat is to seal the porous new plaster, and more importantly, to seal in the inevitable dust on top of the plaster. The only way to get round this, is to wipe down the plaster with a wet rag. The inevitable layer of dust stops normal paint from gripping on to the plaster, and it then peels away.

At the end of the day, it's also about "depending on the paint", because I suspect a lot of cheap value paints could well go on 70/30, but 80/20 is a risk not worth taking, because you don't want to start scrapping the wall off, and starting again.

 

[Gossamer]

Thanks for the comments.
Seems like there's a reasonable chance I have a problem.
Hugely annoying as I did what the plasterer said and also followed Dulux's guidelines, supermatt at 75:25. Is that a cheap paint?!
It's done now...

 

[stevethespreader]

Thanks for the comments.
Seems like there's a reasonable chance I have a problem.
Hugely annoying as I did what the plasterer said and also followed Dulux's guidelines, supermatt at 75:25. Is that a cheap paint?!
It's done now...

Hardly a problem just snag and repaint