Is size really important?

[DrPhill]

Now why did that get your attention? :lol:

We are having some walls plastered, and I have heard that size is important. I assume that size just 'seals' the surface and makes the the plaster less absorbent. We are planning to paint the plaster - would diluted paint do the job? Or would dilute pva glue work better?

Thanks in advance for any advice,

Phill

 

[Grahamshed]

The guy doing a wall at work used dilute PVA. I assumed he knew what he was doing but I guess that doesn't mean it was the only way.

 

[carlb40]

Just water down the first coat of paint. I have worked with a few decorators over the years and they prefer just paint. If you use a watered down pva mix it just sits on the surface and the paint can be just peeled off.

 

[DrPhill]

Just water down the first coat of paint. I have worked with a few decorators over the years and they prefer just paint. If you use a watered down pva mix it just sits on the surface and the paint can be just peeled off.

Would have been nice if the previous owners had done that under the wood-chip paper..... before painting it! #-o

 

[carlb40]

Ahhhhh woodchip, they were probably thinking of you when they put it. Knowing you like woodwork. :lol:


It could have been worse, it could have been vinyl paper :shock:

 

[davem62]

cheap emulsion,but don't use silk ,use matt
hth dave

 

[MMUK]

Leave the plaster for a week to dry out properly then use some B&Q Value (or similar) emulsion watered down 50/50 for a mist coat. This will seal the fresh plaster HTH

 

[tool-me-up]

Pva dries too fast and sits on the surface as said above. I think you need a retarded version of pva ( unsure of name but reading the back it was basically a very thin - slow drying pva - possibly granfix but unsure )
other than that watered down emulsion in a THIN coat - -don't slap it all over or the surface can dry and trap the damp underneath - i found this the hard way when my plaster started to blow a few days after painting.
It was only the very outer surface and easily remedied with a bit of filler but still not the best thing to be doing to a freshly plastered wall.

 

[MARK.B.]

Leave the plaster for a week to dry out properly then use some B&Q Value (or similar) emulsion watered down 50/50 for a mist coat. This will seal the fresh plaster HTH

+1, may take a bit longer than a week in some cases but dont miss out doing a mist coat or you will regret it later when your nice expensive paint starts to peel away from the wall like sunburned skin :shock:

 

[pip1954]

hi plus 1 for mist coat of matt emulsion after plaster has dried
pip :lol:

 

[blackrodd]

Sizing the plaster work prior to papering acted as a sealer and help stop the paste drying out too quickly.
Today a lot of decorators "size" with the paste, it is not a good base for emulsion, as it's too soft.
As you are painting the new plaster, when it's dry, use a slip coat, or mist coat of 50/50 emulsion, (NOT silk as a slipcoat)
I personally don't hold with using cheap paint as a slip coat, The slip coat is doing an important job and I don't see the point in trying to save a couple of pounds cost to slip coat a room.
cheap paint, habits and brushes gets you a cheap looking job.
Plus I have seen the difference in the colour of an odd wall because the slip coat was white and the existing was not.
Unibond/pva tends to set hard, as a sealer and quite often emulsion will not "take" or adhere so well.
HTH Regards Rodders

 

[DrPhill]

Thanks folks - it seems that dilute paint is the way to go. What would happen if I did not dilute the paint?

 

[Phil Pascoe]

It would not penetrate and it would peel off when dry - which is what you're trying to prevent your finish coats doing.

 

[DrPhill]

OK, understood. Thanks. Diluted paint it is.

I now know that size is important.