Undercoat or not

C

Carlo

Guest
Hi

we've just built a new extension and I'm about to paint . Its all newly plastered so the question is are you meant to use undercoat first as its newly plastered or can you put the proper paint on straight away (or does it matter ) ?

thanks for replies
 
You will probably find that the finishing paint will soak into the plasterboard and therefore provide very bad coverage. I read somewhere that you should mix (I think 50 v 50) between the final colour and water as a primer and then the final coat as normal. Make sure it well dried out though, otherwise you will be prone to cracks etc. after the painting is done.
 
stobear said:
You will probably find that the finishing paint will soak into the plasterboard and therefore provide very bad coverage. I read somewhere that you should mix (I think 50 v 50) between the final colour and water as a primer and then the final coat as normal. Make sure it well dried out though, otherwise you will be prone to cracks etc. after the painting is done.
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Most painters will just use plain white emulsion mixed with water as the base primer coat as its the cheapest way to do it....the coloured paint is more than the white paint so tis cheaper to use watered down white as the primer.
 
Hi Carlo

We have just moved into a new house which had plaster walls all over. We did as legend said watered down the white emulison and it then took two coats of our coloured paint to give good even coverage.

Casperjack
 
many thanks for those replies - gives me a good idea now !
 
You can also get a special plaster primer, B&Q and most of the builders merchants should stock this. Used it before on a wall I plastered and only needed a single coat of the final paint to give a good even coat. Might be a little more expensive than using watered down emulsion, but may save you having the time and cost of multiple coats of the final colour.
Leo
 
Do you know how long you should leave plaster to dry before it can be painted?? I had a hole in my ceiling repaired (plastered) and had it painted 9 days later. I can see the outline of the hole (it looks slightly stained) and I have some bubbling on the new plaster. I don't know whether to bother complaining or not.
 
The following is taken from www.dulux.ie:

"[font=Verdana, Helvetica]New plaster must be given enough time to dry completely before painting.[/font]

[font=Verdana, Helvetica]A good guide is when the plaster has turned a light pink colour all over. Wet plaster is a dark beige colour. Skimmed plaster board will dry quite quickly, depending upon the time of year. However, traditional solid construction can take several weeks, especially when conditions are cold and damp.[/font]

[font=Verdana, Helvetica]On new or bare plaster apply a thinned first coat of Vinyl Matt, Soft Sheen or Silk. Thin with up to 1 part water to 4 parts paint".[/font]

The key post on Painting/Wallpapering might be of interest also.
 
Hi Carlo,


We just moved into a new house and only needed 2 coats of paint on the bare plaster walls - we toyed with the idea of undercoating the whole place put decided against it as there was only me and Mr. tomo doing the painting - we bought all Crown paints and the 2 coats on each wall turned out fine - saying that the majority of the house is cream in colour so if you were painting a dark colour you may need 3 coats.

I think undercoating is a waste of time and effort - spend the extra money on a decent tin of paint instead!
 
tomo said:
Hi Carlo,


We just moved into a new house and only needed 2 coats of paint on the bare plaster walls - we toyed with the idea of undercoating the whole place put decided against it as there was only me and Mr. tomo doing the painting - we bought all Crown paints and the 2 coats on each wall turned out fine - saying that the majority of the house is cream in colour so if you were painting a dark colour you may need 3 coats.

I think undercoating is a waste of time and effort - spend the extra money on a decent tin of paint instead!
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I would say you were lucky - the last time I did that I did not get a good finish. The advice to go for high quality paint is valid, but dilute the first coat. The effort is the same as with good paint you should only need one extra coat.
 
My Elvis :D is a painter and he says water down the first coat a lot, then apply the second coat and then if you're giving it a third coat, water it down by about 30%
Some plaster has bondy (not the technical term) stuff mixed into it, the builder should tell you. If the plaster is bonded than that means you might not need as many coats. If it's not, you can buy this pollybond stuff, it looks like glue, mix it with water and paint it on the walls before the first coat. It should turn out super, but who could be bothered going to all that effort. (Well me maybe, nothing worse than a bad paint job!)
 
The ploybond you refer to is PVA or Polyvinyl Acetate- basically white wood glue and is also great for priming bare plaster prior to tiling and for dustproofing concrete.
 
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