New plaster- undercoat ok or need a mist coat?

[baps]

Hi folks,

Just got one room skimmed on some walls, bonded and replastered on other walls. But walls and ceiling are all now freshly plastered.

Guys in the decorating center said this stuff (johnsons professional undercoat) would be fine for an undercoat and no mist coat would be needed. Most of the threads I've been reading here seem to suggest a mist coat is necessary. Can anyone advise if this is suitable? Or if not, why is this?

Many thanks,

Baps.

 

[blightymam]

The stuff you've given is for wood and metal, not plaster - and it's oil based. Not the best thing to put over fresh plaster and best use the right tools for the job. Besides, takes an age to dry and it's more expensive!
Just stick to watered down matt paint, will cost much less, dry quickly and it's the best way to deal with bare plaster. I think your chaps in the decorating center don't know diddly, either that or they are on a cut with Johnstons!

 

[Mattatooi]

lol what the hell. First line of description "Johnstone’s Professional Undercoat is a solvent based undercoat, which can be used for interior and exterior wood and metals. " Some cowboy sales reps you got there.

 

[baps]

lol what the hell. First line of description "Johnstone’s Professional Undercoat is a solvent based undercoat, which can be used for interior and exterior wood and metals. " Some cowboy sales reps you got there.

More or less why I was asking before going ahead with it. Don't know anything about decorating, so figured the decorating center would know best, but see no mention of using it for this.

 

[blightymam]

Don't know anything about decorating,

Well, you do now! Not to use oil-based undercoat that is meant for woodwork on the walls Best thing is to look at the back of the tin if unsure - any wood based paint will be an expensive, smelly and time-consuming job on walls and incorrect.
Best thing is to use a matt emulsion paint watered down as a mist coat, then use whatever finish of emulsion you want on top. Contract matt will be the best for the mist coat, but any proper matt paint should do the trick.

 

[misterhelpful]

I sometimes wonder how people get jobs when they have no knowledge of suitable products. I can understand a cowboy painter using any old paint to slap on but when you are selling from a trade outlet, you have to know your stuff!

http://www.diynot.com/diy/threads/mist-coat-or-pva-bare-surface-basics.425261/

 

[baps]

Yep just didn't know if undercoat was undercoat, or it's advised for wood etc. and be fine on plaster, or what really. Have had trouble covering some of the previous paint with just matt paint in other rooms, and this was also their suggestion for that. I'd bring it back but I've used some on some new skirting board!

Appreciate the help.

Baps.

 

[blightymam]

You don't really undercoat walls - just paint with emulsion (unless bare plaster with the need of a mist coat first). Primer, undercoat and top coats are normally terms in relation to woodwork paint, not walls.

You may be having problems with your walls in the other room because sometimes matt paint doesn't stick very well to emulsions with more of a sheen like silk finish and can give a crazy-paving type finish.

 

[baps]

Other rooms it's more a case of flaking paint, but from help on here and what I've been reading, that's more the original paint hasn't adhered to the wall well. Other places I think it's because there's been a spot of damp. But it was spots like these this undercoat was also suggested for. There's also areas where there's salt has appeared on the walls, but haven't painted those salted bits yet either since what I've been reading here seems to indicate it'd be better to ensure they're fully dry first. So will tackle those after a while I guess.

You think don't use this undercoat on those flaky areas (the non-damp ones)? Same thing again with a mist coat instead?

Baps.