Painting after stripping wallpaper II

[cbasson]

I have some questions which are similar to a previous post (they are different in my mind...):

Having stripped a wall using a steamer, after removing the wallpaper some of the paint below has also come off, leaving patches of plaster coming through.

Do these patches have to be sealed again? Assuming the wall was sealed when the house was built c. 5years ago.

Having already sanded the edges of the patches (to make them smoother)and painted over the wall, I realise that this does not give a good effect....

So, what are my options?
Do I fill round the edges of the old paint/exposed plaster and then re-sand them?
Do I need a non vinyl paint?

Thanks...

 

[noseall]

try hiring a spread to overskim the walls for you provided you don't mind losing some definition of architraves and skirtings

 

[Zampa]

You arnt 'sealing' the plaster as such...your priming it by putting a thinned coat over the bare stuff...it is important.

Try doing that and then sanding the edges of the stuff left behind..if it still shows then you have two choices (apart from getting a plasterer in) you can fill around the edges...sand down and then re coat...but this will probably leave 'scars' behind...personally id for for lining paper.

You only need non vinyl emulsion when the plaster is new and the walls need to be allowed to 'breathe'

 

[cbasson]

ok, what happens if walls arent primed properly?

 

[Zampa]

ok, what happens if walls arent primed properly?

Off comes the paint!

What actually happens is...if you put a thick coat of paint over a porous surface the water content of the paint is absorbed into the wall leaving the pigment part just sitting on the top..by thinning the paint it allows moisture and pigment to be drawn in...thus 'locking it on' to the surface...most primers work like this apart from those that lock on by causing a chemical reaction with the surface...or in the case of say gloss on plastic..it sticks the surfacelike cling film stick to a window but doesnt lock on to it...so when the plastic expands and contracts..the gloss moves with it..thats why its said to only gloss a radiator and not use undercoat, which is considered more britle because of the amount of pigment used and possibly the use of long/short oil in the production

 

[Northbeach]

Same happened to my walls. The wallpaper was really difficult to come off despite using steaner and razor like scraping tool.
If I'd gone for a skim (which we had not budgted for) then I'd lose the definition (as mentioned above) on the skirting and frames etc. It's a fairly old house so I guess it adds character .
Didn't think of priming the bare plaster (the patches - almost look like a map - under the old paint) though.
...and what's lining paper ?

 

[Zampa]

Lining paper is an off white plain pulp paper used for a few different reasons in decorating..evening out the porosity of a wall...providing a better surface to paint on or paper.

Its quite cheap too...about 2.50 for a douple roll...it comes in various grandes which are in relation to the weight in grams of the paper..400, 600, 800,1000,1200,1400...theres also one which has a cotton scrim on the back for walls that are prone to cracking.

400 is white lining paper and idal to paint on...but its very thin as is 600...and difficult to hang...1000+ grades are fine for use under wallpaper...but can leave a bumpy'surface' when painting over...so IMO 800 is the better one to take paint.