Marks on new plaster wall

JustAnotherSaver

Thanks.

I started with some 180 grit this morning actually.

In some sections it didn't remove marks but in others it's at least done something...

For example - in the first photo, you see where i've put the red X. I think this is PVA. It's very sticky when i wipe with a damp cloth & there's a milky residue afterwards. Well if you look above the light switch in that photo you'll see finger drag marks where they've obviously ran their fingers down the wall - i rubbed & rubbed with a damp cloth until the section finally did turn dark (took some good rubbing).

I then let it dry out

^^ Whether that bit was necessary or not i don't know but my thought process was i basically don't want to be sanding glue (assuming it is PVA)

Once it had dried out i sanded with 180 grit.

I then wiped it with a damp cloth again & now there's no finger marks showing through.

JustAnotherSaver

Well i've been sanding & wiping down with a damp cloth & the strange marking is still showing through.

I don't know whether wiping down with a damp cloth is a fair indication as to the condition of the wall but i'm hesitant to get a load of paint all over the room only to find out 80% of it was a waste of time. At least with water it can dry out & disappear in no time.

Take this wall (the one with the socket - not the one to the right) for example...

I wiped that down, pretty much the full length with a damp cloth. Look how patchy it is. Sections of it don't even look like water has touched it.

Is that normal? Like i say, i'm hesitant to just throw paint on there only to find out i wasted my time. If it looks like water hasn't touched it, my thought process is it'll do the same for paint, surely.

The wall to the right of that was the same...


This was all done by the second plasterer we had in.

But i keep showing you photos of wet walls :rotfl:So i took a dry one that they (Second plasterer) did. I saw the areas that i thought would react the same (look like water hadn't touched it) & sure enough it turned out the same.....




Compare this to a wall that the third plasterer we had in did....

Never mind the streaks in the lower section - that's only because it had started drying out.

When i wiped that wall down with a damp cloth the entire thing looked even with the exception of that small circle part near the top left section of where it's been dampened which wouldn't go dark which is only because it needed filling a bit there.




If this is any indication as to how paint will perform then that's a hell of a lot of sanding (& i've already sanded).


Is there a product out there (i know Zinsser do a lot of marvellous save-the-day products) that i can put on on top of all of this & then paint on top of that?

JEN22

Could be a damp problem

jcb208

Don't worry light rub down and paint it,The plaster has been over troweled which causes non porous shiny surface, this is very common we get it all the time at work on new build plastered houses

JustAnotherSaver

Damnit. I just typed out this reply & accidentally hit the back button on my mouse & lost it all

Anyway, very briefly now....

jcb - i know you say rub it & paint and i've done this for a test patch but it still shows through as it does when dampened. I can't help but feel that even with 200 coats you'll still see a two-tone effect.

Also for the 3rd photo, i took a scraper to it & the bits that look sound stayed on & the patchy bits scraped off. Not real easy but they scraped easier than the sound bits.

JustAnotherSaver

Before i hit the sack, in case there's any experienced decorators reading this ....

in your experience, is there any way at all that layering up the paint 'as normal' (so 1:1 coat of supermatt, followed by say a couple 70:30 coats of supermatt as advised on the tub & then perhaps a couple of coats of the finish paint) - is there any way you can see that covering these walls evenly?

Or is it one of those - never going to happen in a million years, don't waste your time kind of things (i.e. go try something like Zinsser Gardz)?

keith969

What paint are you using? If it's decent stuff like deluxe or crown applied neat then you have a problem, if it's B&Q brand then get better paint.

phil24_7

The final picture in the original post is exactly the same as I had in my cellar and is caused by over polishing of the plaster. It would have been noticeable but only if looking across it to see the reflection of any light.

A lights sand with a 240 grit should do.

The problem you may have is that as you have tanked, the wall will only dry one way and will also not adhere as well as normal (it won't 'suck' into the substrate) so it can require more polishing or forcing back to the substrate to avoid slumping.

JustAnotherSaver

Paint is Dulux Super matt at a 1:1 ratio.

I painted over the first photo where i've put red X marks yesterday. Used a wallpaper scraper today & the paint didn't lift.

However in the THIRD photo of this thread - the part i painted that looks blotchy, where i run the scraper over the blotches, the paint lifts/scrapes off. I'm fairly sure although not 100% that i sanded this area too.



Regards the sandpaper, i've now been told grits ranging from 120grit to 240grit lol.


I've contacted Zinsser & Sovereign chemicals & i need more feedback from them but at the moment it's looking like Zinsser Gardz, simply because of the K11 tanking, is NOT going to be suitable in this scenario.