Paint Staining - New Plaster

tedimc

So I have renovated an old house and insulated, slabbed and re-skimmed the inside walls.

The plaster seemed to be well dryed out before I sprayed the walls with 2/3 coats of watered down dulux matt paint (total cover) and then another 2 coats of dulux soft sheen (white).

After a few days I noticed some brown staining around the windows/external corners where the angel bead is (even though I had applied some water based BIN 123.

However, worse still - I have noticed some large brown patches on some walls no where near the angel beads. Has anyone seen this before? And what can I use to cover it? I'd prefer not to have to roll the full walls but will if I have to. No sand/cement was used, only a little bonding in certain areas.

BrokenArrows

tedimc wrote: »

So I have renovated an old house and insulated, slabbed and re-skimmed the inside walls.

The plaster seemed to be well dryed out before I sprayed the walls with 2/3 coats of watered down dulux matt paint (total cover) and then another 2 coats of dulux soft sheen (white).

After a few days I noticed some brown staining around the windows/external corners where the angel bead is (even though I had applied some water based BIN 123.

However, worse still - I have noticed some large brown patches on some walls no where near the angel beads. Has anyone seen this before? And what can I use to cover it? I'd prefer not to have to roll the full walls but will if I have to. No sand/cement was used, only a little bonding in certain areas.

You said it seemed to be well dried...how many days did you leave it to dry?

tedimc

BrokenArrows wrote: »

You said it seemed to be well dried...how many days did you leave it to dry?

At least 2 weeks, some walls had 4+.

I thought it may have been the walls that were plastered last, but not necessarily- it is also on some that were plastered early on. These were almost white when painted. The common element seems to be the walls which needed quite a bit of bonding to help even them out. Would PVA leach through the paint like this??

antiskeptic

tedimc wrote: »

Would PVA leach through the paint like this??

Good question. PVA is water soluble and there's water in the emulsion paint going over it. Would it not just dissolve when you attempt to paint it?


Perhaps it takes time for the pva to go off and you didn't leave enough time. Reading the instructions on some pva I've got, the directions for sealing are pretty sketchy..

Roscommon John

antiskeptic wrote: »

Good question. PVA is water soluble and there's water in the emulsion paint going over it. Would it not just dissolve when you attempt to paint it?


Perhaps it takes time for the pva to go off and you didn't leave enough time. Reading the instructions on some pva I've got, the directions for sealing are pretty sketchy..

Bonding is a devil for holding moisture, especially if it was a heavy coat over pva, then skimmed.The beads were probably stuck with bonding or filled out with it also. It's moisture leaching out of the bonding that's staining the paint. You need a dehumidifier to dry it out properly, then re prime with bin, I'd recommend the red tin solvent based. Then re- paint I'm afraid.

tedimc

Ok - thanks lads.

ouxbbkqtswdfaw

Hi, paint around the angle bead and wall patches with oil based white undercoat. If patch is still showing repaint. Then cover with wall emulsion paint.

antiskeptic

Roscommon John wrote: »

Bonding is a devil for holding moisture, especially if it was a heavy coat over pva, then skimmed.The beads were probably stuck with bonding or filled out with it also. It's moisture leaching out of the bonding that's staining the paint. You need a dehumidifier to dry it out properly, then re prime with bin, I'd recommend the red tin solvent based. Then re- paint I'm afraid.

Makes sense - except that the photos show significant areas of staining well away from the beading.

I wonder OP was the wall just (slabbed) and skimmed - or was there repair work done to patches which would involve bonding. Your plasterer might be able to say.

Roscommon John

antiskeptic wrote: »

Makes sense - except that the photos show significant areas of staining well away from the beading.

I wonder OP was the wall just (slabbed) and skimmed - or was there repair work done to patches which would involve bonding. Your plasterer might be able to say.

"At least 2 weeks, some walls had 4+.

I thought it may have been the walls that were plastered last, but not necessarily- it is also on some that were plastered early on. These were almost white when painted. The common element seems to be the walls which needed quite a bit of bonding to help even them out. Would PVA leach through the paint like this??"

The walls were bonded also, I can almost 100% guarantee it's moisture coming from the bonding that's causing the stains, it's the vermiculite in the bonding that holds the water. It needs a dehumidifier to dry it out.

antiskeptic

Roscommon John wrote: »

The walls were bonded also, I can almost 100% guarantee it's moisture coming from the bonding that's causing the stains, it's the vermiculite in the bonding that holds the water. It needs a dehumidifier to dry it out.

Ah thanks. I missed that.

Strange that. I'd a room repaired a few years back with areas of bonding and the whole thing skimmed and never had an issue with staining.

What you say makes sense though.

Do builders take dehumidifiers to rooms before painting - I've never heard of it

tedimc

Roscommon John wrote: »

It needs a dehumidifier to dry it out.

I was told by a few people that you should never use a dehumidifier - it dries out the plaster/concrete/etc too quickly and will make it prone to cracking.

The walls are painted well over 3 or 4 weeks at this stage. Do you think the bonding is still drying out, or is it just a matter of me repainting the affected walls?

Regarding the beading, I gave them a coat or two of the water based BIN 1-2-3 but I got a lot of mapping in those areas as the paint took a lot longer to dry where it was primed.

It's a real pity, because the other walls all came out brilliantly and the sprayer gave a lovely finish.

antiskeptic

tedimc wrote: »

I was told by a few people that you should never use a dehumidifier - it dries out the plaster/concrete/etc too quickly and will make it prone to cracking.

The walls are painted well over 3 or 4 weeks at this stage. Do you think the bonding is still drying out, or is it just a matter of me repainting the affected walls?

Regarding the beading, I gave them a coat or two of the water based BIN 1-2-3 but I got a lot of mapping in those areas as the paint took a lot longer to dry where it was primed.

It's a real pity, because the other walls all came out brilliantly and the sprayer gave a lovely finish.

I'm painting a newly plastered house starting tomorrow - with bonded parts (damage holes filled and beading attached here and there). Will let you know how I get on. First room up is about 3 weeks dry so lets see..

Roscommon John

tedimc wrote: »

I was told by a few people that you should never use a dehumidifier - it dries out the plaster/concrete/etc too quickly and will make it prone to cracking.

The walls are painted well over 3 or 4 weeks at this stage. Do you think the bonding is still drying out, or is it just a matter of me repainting the affected walls?

Regarding the beading, I gave them a coat or two of the water based BIN 1-2-3 but I got a lot of mapping in those areas as the paint took a lot longer to dry where it was primed.

It's a real pity, because the other walls all came out brilliantly and the sprayer gave a lovely finish.

Yep letting naturally dry is recommended, no harm using dehumidifier when walls are gone white and leave a white powder on fingertips when rubbed. Especially if bonding was used. As for mapping after priming, give a light rub of sand paper, 250 or 500 grit to key the primer, bin is great but leaves a shellac finish, causing finish coat to slick and map. A mohair roller is great for applying bin, you have to be quick and don't go over it when it's tacky or it will creal and leave lines or brush marks that will show under finish coat. The light sanding helps.

antiskeptic

antiskeptic wrote: »

I'm painting a newly plastered house starting tomorrow - with bonded parts (damage holes filled and beading attached here and there). Will let you know how I get on. First room up is about 3 weeks dry so lets see..

Wierd..

I've painted 3/4 of the house with it's sealing coat(thinned by 10% Crown "obliterating" emulsion). The beading showed through but a second run with the roller next day covered that. Areas which I know are patch bonded under the skim / beads attached with bonding / ceilings which have all been bonded first) are all fine.

But..

In one small room - the very first one plastered perhaps 8 weeks ago - things are different.

- the ceiling has this horrendous mapping patchwork. Areas have taken the paint fine and other areas have taken it but show through as a dark grey. I tried a second coat but to no avail.

- an area (in the same room) that was spot bonded under the skim continued to show through when putting on the sealing coat. I've done another couple of coats of the thinned emulsion and it's been covered and not showing through anymore.

Plasterer is dropping by tomorrow to have a look.

Thank God it didn't affect the whole gaff is all I can think...

tedimc

Any photos?

I hate to say it, but would there be a delay in your issues appearing?

For example - my walls appeared fine at first and then started to show the staining maybe a week or so later.

BrokenArrows

Had my house reskimmed, just waiting for it to fully dry. Hopefully I don't experience these issues.

antiskeptic

tedimc wrote: »

Any photos?

I hate to say it, but would there be a delay in your issues appearing?

For example - my walls appeared fine at first and then started to show the staining maybe a week or so later.

A couple of weeks in and its as it was - all is fine apart from a small area. This problem area not only has this mapping effect but the "land" parts of the map have a decided step down to the "sea" areas. It's an ugly mottled effect.

I noticed a small patch of the same mottled effect on an area of the wall which I know was bonded to take a bad hollow out of the sheeting (the rest of the room was just skimmed). Same room done on the same day with the same materials.

Despite 3 coats at this point, the sea is darker than the land. Not sure how to deal with it. Perhaps orbital sand and some BIN?

God forbid it be house wide. Absolute 'mare

I'll see if I can photo at some point - although the effect is subtle enough even to the naked eye. You'd have to be lying in your bath gazing at the ceiling to notice it..

tedimc

antiskeptic wrote: »

Despite 3 coats at this point, the sea is darker than the land. Not sure how to deal with it. Perhaps orbital sand and some BIN?

Yes - I think a sander is the best bet. I'm going to try that on the areas of mapping on my walls.

Careful with the BIN, that's what caused my mapping in the first place. The paint dryed differently and seem to coat a lot heavier in the areas I primed.