Recently skimmed bathroom

Mike-H · 20 Mar 2007

I have recently skimmed over two walls in my bathroom. In addition I have skimmed the periously stippled ceiling. Due to my amazing diy skills they both required some sanding to get a nice finish.

Now that they are smooth how should i prepare these walls prior to adding the bathroom emulsion? I have been told to PVA the surface first is this right? What is the best technic?

Cheers

Mike (diy numpty)

Zampa · 20 Mar 2007

Mike-H said:
I have recently skimmed over two walls in my bathroom. In addition I have skimmed the periously stippled ceiling. Due to my amazing diy skills they both required some sanding to get a nice finish.

Now that they are smooth how should i prepare these walls prior to adding the bathroom emulsion? I have been told to PVA the surface first is this right? What is the best technic?

Cheers

Mike (diy numpty)

Noooooooooooooooooooooooooooooooooooooooooooooooooo...

AndyBill · 21 Mar 2007

why dont you try putting paint on instead? it covers better than pva and it comes in a range of colours !

Mike-H · 21 Mar 2007

Excellent work. I have proved my diy stupidity with one post

The surface is quite dusty. The skim on the walls is less than 1mm thick as I was simply covering some badly cracked paint. The ceiling is about 1-2mm. Can I simply paint straight onto this? I was under the impression that the plaster needed some king of base coat. Is this not true? Why would someone recommend PVA?

Mike

Zampa · 21 Mar 2007

Its just an old wifes/bulders/chancers tale mate..

It could casue you so mant problems in the future..

You wont find it on any technical paperwork from paint companies

Third_Eye · 21 Mar 2007

Mike-H said:
Excellent work. I have proved my diy stupidity with one post

The surface is quite dusty. The skim on the walls is less than 1mm thick as I was simply covering some badly cracked paint. The ceiling is about 1-2mm. Can I simply paint straight onto this? I was under the impression that the plaster needed some king of base coat. Is this not true? Why would someone recommend PVA?

Mike

Why would someone tell us that they have WMD when they do not !

Third_Eye · 21 Mar 2007

AndyBill said:
why dont you try putting paint on instead? it covers better than pva and it comes in a range of colours !

Well put "AndyBill".

Hehe.

serge33 · 21 Mar 2007

read this

http://www.diydoctor.org.uk/projects/paintnewplaster.htm

use thinned down emulsion or in bathrooms and kitchens where an egg shell type paint may be used use thinned PVA.

Third_Eye · 21 Mar 2007

Just read the link there "serge33".

All water based emulsions allow miosture to pass through it. This is why vinyl wallpaper can be hung over emulsions. However, try hanging vinyl wallpaper over oil-based paints then the miostue from the paste will become trapped.

I explain this scenario on above paragraph as clear evidence that the link contradicts itself. They go on about trapped miosture in plaster and then go on to advize applying PVA then apply oil-based eggshell in Kitchen & Bathrooms !

Oil-Based Eggshell actually traps miosture in plaster and can cause longterm damp-like conditions to evolve in the plaster. Especially in Kitchen & Bathrooms on plaster that is applied directly to an outside wall.

Also, what happens to PVA when it has trapped miosture around it ? It turns back to white. This can cause problems with future decoration i.e blistering etc

Also, what happens when you have Plaster, PVA, and an Oil-Based Paint all next to each other when trapped miostire is in the plaster ? It makes the miosture unable to pass through the Oil-Based Paint. Therefore creating a surface that will eventualy become damp, due to trapped miosture, because of the Oil-Based Eggshell. Hence explanation on second paragraph.

The thing about plaster that has been applied directly onto brick etc is that it must be allowed to breath in order not to create trapped miosture. By applying an Oil-Based Eggshell on explanied scenario can actually cause damp !

Rant over.

Zampa · 22 Mar 2007

If you intend to put an oil based paint on the surface, such as eggshell or gloss, then the surface cab be sealed using a solution of PVA adhesive. This is mixed at the same ratio.

What a load of ol ****!

If you are intending to paint a new bare plaster/cement rendered wall in oil based eggshell you should always use alkali resisting primer sealer..if you dont your liable to end up with 'alkali burn' or saponification...which is caused by the high alkali content of the surface.

Finds me a paint manufacturer that states PVA as a primer for oil based eggshell.

And whoever wrote that talks of 'sealing' the walls with mist coat...as mist coat is not a sealer..its a primer coat...it make the surface ready for more coats,..it primes it.

Third_Eye · 22 Mar 2007

To my shock "Zampa" i missed that bit.

Also, no that i am attacking the diydoctor hingy, but i also noticed that it reads, "The surface can be sealed using a solution of PVA adhesive. This is mixed at the same ratio." What ratio is it refering to !

Is it refering to the same ratio as on when it reads, "Then mix some of that emulsion paint with a=water at a ratio of 4 parts paint to 1 part water and stir thoroughly."

If this is the case then by mixing 4 parts PVA with 1 part water, then i am afraid you are guaranteed this mix will blister almost instantly when paint is applied above it.

Thing about PVA is it can be used in unique occasions but you need to know what you are doing.

Though the thing i do not understand is PVA is clear once dry and it does not help newly plastered walls. So, why on earth apply it to new/bare plaster ! It is a waste of time.

Best emulsion for new/bare plaster is Dulux Trade Supermatt.

Why ? Because it DOES NOT need an sealer. It can be applied even when the plaster has NOT fully dried. It can be applied 48 hours after plaster application (Though Dulux Fast Matt can be applied after 24 hours). It is breathable.

I could go on and on.

beinerts · 23 Mar 2007

So what if you were to use PVA mix on a bathroom wall (brick or whatever) and then use a bonding plaster, then a finishing plaster. Would that still cause problems? I'd have thought not, but if moisture does pass through the plaster and the PVA loosens, would the entire plaster coat fall off comically?

Zampa · 23 Mar 2007

Dunno..but it aint any good as a base for paint.

Third_Eye · 23 Mar 2007

beinerts said:
So what if you were to use PVA mix on a bathroom wall (brick or whatever) and then use a bonding plaster, then a finishing plaster. Would that still cause problems? I'd have thought not, but if moisture does pass through the plaster and the PVA loosens, would the entire plaster coat fall off comically?

Good question "beinerts".

Though i have personaly never had any bad experiences with using PVA whilst plastering.

However in terms of what you point out in terms of a bathroom then i do not see any probs occuring as the PVA will be in behind bonding plaster and a finish coat (assuming there is no damp).

The problem with PVA when over painted is due to the two products being in direct contact with each other.

I will give you an example. When PVA has been used in an paint tray and left to dry and then you use the paint tray the next day and so on for 3 days, then this makes the new coating of emulsions on the tray to blister !

This may happen to PVA walls but will only become apparent years down the line.

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Recently skimmed bathroom

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