Drying time before re-skim

8allerob

New Member
Hi all,

I’ve got a wall in my house that I’m using as a practice wall, before deciding whether to go DIY or wait 3 months for a pro. The wall in question is getting taken back to brick and boarded, so making a b*ll***s of it, which I have just done, isn’t anything to concerning.

I’ve skimmed it today, some of it is ok, other bits are a disaster thanks to over mixing the first coat, with the 2nd coat just pulling bits of it off. Do I need to wait for the plaster to fully dry before re-applying PVA and attempting again ? Or should I prep with something else ?
 

paulf

Well-Known Member
Hi all,

I’ve got a wall in my house that I’m using as a practice wall, before deciding whether to go DIY or wait 3 months for a pro. The wall in question is getting taken back to brick and boarded, so making a b*ll***s of it, which I have just done, isn’t anything to concerning.

I’ve skimmed it today, some of it is ok, other bits are a disaster thanks to over mixing the first coat, with the 2nd coat just pulling bits of it off. Do I need to wait for the plaster to fully dry before re-applying PVA and attempting again ? Or should I prep with something else ?
Pictures would help.
 

8allerob

New Member
218EADCA-9A7D-4151-A140-0B5E912ACBC1.jpeg

Pictures would help.
Oh god ok, I’m ready for it
 

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8allerob

New Member
Previously wallpapered but all the old bonding or hard wall is blown.

Applied 2 coats of PVA, then definitely over mixed the first coat (in hindsight) and the 2nd coat of PVA had dried out. Possibly also started the 1st trowel a bit early as well.

I gave it up as a bad job when applying the 2nd coat as it was bringing the first coat off, so some bits only have one coat and low spots.

As mentioned in the OP it’ll be removed anyway for boards but just fancied another go at it. Despite looking terrible, some bits are smooth, which is what I’m clinging on to.
 
Last edited:

paulf

Well-Known Member
Previously wallpapered but all the old bonding or hard wall is blown.

Applied 2 coats of PVA, then definitely over mixed the first coat (in hindsight) and the 2nd coat of PVA had dried out. Possibly also started the 1st trowel a bit early as well.

I gave it up as a bad job when applying the 2nd coat as it was bringing the first coat off, so some bits only have one coat and low spots.

As mentioned in the OP it’ll be removed anyway for boards but just fancied another go at it. Despite looking terrible, some bits are smooth, which is what I’m clinging on to.
You had a go and it didn't work out, it's getting ripped out anyway.
Just wack some pva on and keep going.
 

8allerob

New Member
You had a go and it didn't work out, it's getting ripped out anyway.
Just wack some pva on and keep going.
Yeah, I’ll have another go. Am I best to let that dry first before applying PVA again ? Is there anything else I should consider to help it bond ?(not sure that was the issue)
 

8allerob

New Member
You may get some stick but we’ve seen people claiming to be plasterers doing worse
Mate, just seen a post on another thread from someone who paid for a job not that much better !

What I have learnt from today is that it is easy to get in a flap and panic with it haha. That’s why it’s a terrible job as opposed to ‘not good’ Need to just stay calm.

Big respect to the Pros. So many people have said they’ll try their hand at most things, but not plastering
 

MakeItSmooth

Well-Known Member
Previously wallpapered but all the old bonding or hard wall is blown.

Applied 2 coats of PVA, then definitely over mixed the first coat (in hindsight) and the 2nd coat of PVA had dried out. Possibly also started the 1st trowel a bit early as well.

I gave it up as a bad job when applying the 2nd coat as it was bringing the first coat off, so some bits only have one coat and low spots.

As mentioned in the OP it’ll be removed anyway for boards but just fancied another go at it. Despite looking terrible, some bits are smooth, which is what I’m clinging on to.


A few other things to consider; some or none of which may apply to your situation:


1) was the wall already damp before you started?

I'm not suggesting it was, but it is one possibility (of many) which can lead to problems with the first layer of plaster peeling off the wall (or sliding around on the wall) when you try to apply the second coat. Timings are also important (and will vary depending on room temperature, how clean your bucket and mix water was, how dry your wall is, how porous your wall is, how fresh your bag of plaster is, etc. etc.), but I'm sure you realise that.

The same is true, even with a dry wall, with regard to your PVA coat(s) - they must be properly tacky (or dry) on the entire wall - if there are still areas on the wall where the PVA is 'wet', then you will not do well if you try to apply plaster - it will tend to skid around on the wall, and may peel off. The PVA must also have been diluted enough for it to penetrate the wall a bit, rather than just forming a skin on the surface. Also, if you apply too much PVA (even if it's correctly diluted), you can create a situation where the wall is no longer porous enough to allow the applied plaster to 'pull-in' nicely within an expected period of time.

2) if a wall was previously wallpapered, just removing the wallpaper and slapping on PVA can lead to problems. The remaining residue of wallpaper paste may not be visible but can lead to very poor adhesion of the plaster (which, again, can lead to it peeling off the wall or sliding around on the wall, when you try to apply the second coat). Remember, wallpaper paste, PVA and plaster are all affected by water.

3) did you mix your plaster quite thick? It needs to be like melted icecream, not mixed like wet clay.
 

Stewie03

Well-Known Member
Pva and skim it you will find the wall will dry quicker when skimming over a newly plastered wall though so take that into consideration
 

8allerob

New Member
A few other things to consider; some or none of which may apply to your situation:


1) was the wall already damp before you started?

I'm not suggesting it was, but it is one possibility (of many) which can lead to problems with the first layer of plaster peeling off the wall (or sliding around on the wall) when you try to apply the second coat. Timings are also important (and will vary depending on room temperature, how clean your bucket and mix water was, how dry your wall is, how porous your wall is, how fresh your bag of plaster is, etc. etc.), but I'm sure you realise that.

The same is true, even with a dry wall, with regard to your PVA coat(s) - they must be properly tacky (or dry) on the entire wall - if there are still areas on the wall where the PVA is 'wet', then you will not do well if you try to apply plaster - it will tend to skid around on the wall, and may peel off. The PVA must also have been diluted enough for it to penetrate the wall a bit, rather than just forming a skin on the surface. Also, if you apply too much PVA (even if it's correctly diluted), you can create a situation where the wall is no longer porous enough to allow the applied plaster to 'pull-in' nicely within an expected period of time.

2) if a wall was previously wallpapered, just removing the wallpaper and slapping on PVA can lead to problems. The remaining residue of wallpaper paste may not be visible but can lead to very poor adhesion of the plaster (which, again, can lead to it peeling off the wall or sliding around on the wall, when you try to apply the second coat). Remember, wallpaper paste, PVA and plaster are all affected by water.

3) did you mix your plaster quite thick? It needs to be like melted icecream, not mixed like wet clay.
Thanks for your comments. I’m pretty sure the wall wasn’t damp before starting but I’ll check the PVA coat is tacky all over before starting my 2nd attempt as I didn’t fully check to be honest.

I know the plasterer that did the other rooms in the house had some issues with the plaster reacting to the old wallpaper paste. Obviously he had the know how to handle it rather than panic like I did ! It’s probably not ideal to have a first attempt on an old wall as opposed to boards

I faffed about mixing it for too long and I’m 99% sure it ended up too thick. I’m using an SDS attachment, so that’s probably not ideal, but as it’s likely to be my first and last attempt I didn’t want to spend on a paddle mixer
 

Brimstone

Well-Known Member
Timings are everything. On some jobs I use a bucket trowel to mix, and I have an old splodger if need be, but you don't want to spend too long mixing, out of your 20mins to get it on the wall. Then you need patience to leave it alone to firm up a bit before flattening and getting a second coat on. Then more patience...
 

Retired Spread

Well-Known Member
Thanks for your comments. I’m pretty sure the wall wasn’t damp before starting but I’ll check the PVA coat is tacky all over before starting my 2nd attempt as I didn’t fully check to be honest.

I know the plasterer that did the other rooms in the house had some issues with the plaster reacting to the old wallpaper paste. Obviously he had the know how to handle it rather than panic like I did ! It’s probably not ideal to have a first attempt on an old wall as opposed to boards

I faffed about mixing it for too long and I’m 99% sure it ended up too thick. I’m using an SDS attachment, so that’s probably not ideal, but as it’s likely to be my first and last attempt I didn’t want to spend on a paddle mixer
walls with old wallpaper paste/paint etc... on them will require a mechanical key for the plaster to adhere so they should be gritted rather than water/pva
 

8allerob

New Member
walls with old wallpaper paste/paint etc... on them will require a mechanical key for the plaster to adhere so they should be gritted rather than water/pva
Cheers mate

So blue grit if previously wallpapered ? But now I’ve got a ‘base coat’ of plaster, I can go with just PVA ?

Wondering now if it’s less of a gear issue and probably a balls up in the prepping of it. Most likely both with my lack of skill the icing on top !

Just a final question - should I use Easi fill in the spots where the plaster has pulled off or just fill them in with my first coat ?
 

Retired Spread

Well-Known Member
Cheers mate

So blue grit if previously wallpapered ? But now I’ve got a ‘base coat’ of plaster, I can go with just PVA ?

Wondering now if it’s less of a gear issue and probably a balls up in the prepping of it. Most likely both with my lack of skill the icing on top !

Just a final question - should I use Easi fill in the spots where the plaster has pulled off or just fill them in with my first coat ?
blue grits not that nice to use, does the job but Bond-it or bostik stabilizing primer are nicer to use.

couple of coats of 4:1 water pva should be enough to control suction on that.......you don't to completely kill it and 1st coat should fill low spots.

I'd say devil float it before prepping it but it looks rough as fk so key should already be good :coffe:
 
It’s normally around 10-15 mins in between the flattening process my guess is your scraping the balls out of it leaving it really thin just apply a little thicker .. should be using minimal water also.
Easier said than done but hope it helps
 

8allerob

New Member
Well the 2nd attempt today went better. Mixed it a bit thin and/or probably could have got away with just 1 PVA coat, as it was a bit slippy on the wall and running off the hawk.

If I have another go I will definitely get a paddle mixer. The SDS is not ideal.

Trainers had an inch of plaster on them at the end as well !

Got a better rhythm when the 2nd coat went off a touch and that saved the job. Not sure how long it’d actually last, but as it’s getting knocked off, not too bothered.

Thanks for the advice
 
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