Hi,

I am attempting to apply a top coat of plaster onto a smallish area
(not the whole wall) where the top coat has come away due to
renovations work.

I am using Finishing plaster and following the instructions on the
back.

The base coat already on he wall is a sand and cement based render. I
apply the top coat(skim) approx 2-3mm thick. It goes on OK, but once
dry, cracks appear int he new plaster. It aso does not bond well and
just comes away.

I think the sand and cement coat is sucking all the water from the new
plaster.

Whats the soloution. Removing the sand and cement coat is not an
option at the moment.

Thanks

Bhupesh

On 18 Jun, 10:01, bp wrote:
Hi,

I am attempting to apply a top coat of plaster onto a smallish area
(not the whole wall) where the top coat has come away due to
renovations work.

I am using Finishing plaster and following the instructions on the
back.

The base coat already on he wall is a sand and cement based render. I
apply the top coat(skim) approx 2-3mm thick. It goes on OK, but once
dry, cracks appear int he new plaster. It aso does not bond well and
just comes away.

I think the sand and cement coat is sucking all the water from the new
plaster.

Whats the soloution. Removing the sand and cement coat is not an
option at the moment.

Thanks

Bhupesh

Brush on a coat of PVA to seal the area and stop it absorbing all the
water from the finishing plaster?

Mark.

On 18 Jun, 10:12, wrote:
On 18 Jun, 10:01, bp wrote:





Hi,

I am attempting to apply a top coat of plaster onto a smallish area
(not the whole wall) where the top coat has come away due to
renovations work.

I am using Finishing plaster and following the instructions on the
back.

The base coat already on he wall is a sand and cement based render. I
apply the top coat(skim) approx 2-3mm thick. It goes on OK, but once
dry, cracks appear int he new plaster. It aso does not bond well and
just comes away.

I think the sand and cement coat is sucking all the water from the new
plaster.

Whats the soloution. Removing the sand and cement coat is not an
option at the moment.

Thanks

Bhupesh

Brush on a coat of PVA to seal the area and stop it absorbing all the
water from the finishing plaster?

Mark.- Hide quoted text -

- Show quoted text -

Also perhaps score the sand/cement coat to provide a key for the top
coat?

OK,


Thanks for the replies.

2 more questions about PVA.

Could I use any PVA. I have some childrens PVA glue type stuff. Or
should I get some specific for plastering - which I guess I could get
from BQ.. I would say I only need a little bit though

How do I apply it. Thinned (with Water?) Or direct. How long do I
wait after applying PVA to apply the plaster?


Many Thanks

Bhupesh

On Mon, 18 Jun 2007 04:05:25 -0700, bp wrote:



OK,


Thanks for the replies.

2 more questions about PVA.

Could I use any PVA. I have some childrens PVA glue type stuff. Or
should I get some specific for plastering - which I guess I could get
from BQ.. I would say I only need a little bit though

PVA is about £10 for 5 Litres at Wickes. Small quantites are going to
be pretty cheap so may as well use the correct thing.

How do I apply it. Thinned (with Water?) Or direct. How long do I
wait after applying PVA to apply the plaster?


I just paint on the PVA neat, then I mix the plaster which takes a few
minutes then I apply it over the PVA straight away.


Many Thanks

Bhupesh

wrote:
On 18 Jun, 10:01, bp wrote:
Hi,

I am attempting to apply a top coat of plaster onto a smallish area
(not the whole wall) where the top coat has come away due to
renovations work.

I am using Finishing plaster and following the instructions on the
back.

The base coat already on he wall is a sand and cement based render. I
apply the top coat(skim) approx 2-3mm thick. It goes on OK, but once
dry, cracks appear int he new plaster. It aso does not bond well and
just comes away.

I think the sand and cement coat is sucking all the water from the new
plaster.

Whats the soloution. Removing the sand and cement coat is not an
option at the moment.

Thanks

Bhupesh

Brush on a coat of PVA to seal the area and stop it absorbing all the
water from the finishing plaster?

Mark.

no. Soak the wall that you are plastering first.

And score it too.

On Mon, 18 Jun 2007 12:25:15 +0100, The Natural Philosopher
wrote:

wrote:
On 18 Jun, 10:01, bp wrote:
Hi,

I am attempting to apply a top coat of plaster onto a smallish area
(not the whole wall) where the top coat has come away due to
renovations work.

I am using Finishing plaster and following the instructions on the
back.

The base coat already on he wall is a sand and cement based render. I
apply the top coat(skim) approx 2-3mm thick. It goes on OK, but once
dry, cracks appear int he new plaster. It aso does not bond well and
just comes away.

I think the sand and cement coat is sucking all the water from the new
plaster.

Whats the soloution. Removing the sand and cement coat is not an
option at the moment.

Thanks

Bhupesh

Brush on a coat of PVA to seal the area and stop it absorbing all the
water from the finishing plaster?

Mark.

no. Soak the wall that you are plastering first.

And score it too.

I agree with the above. Forget the PVA. Obviously it should not be
running with water!

On Mon, 18 Jun 2007 02:01:35 -0700, bp wrote:

Hi,

I am attempting to apply a top coat of plaster onto a smallish area
(not the whole wall) where the top coat has come away due to
renovations work.

I am using Finishing plaster and following the instructions on the
back.

The base coat already on he wall is a sand and cement based render. I
apply the top coat(skim) approx 2-3mm thick. It goes on OK, but once
dry, cracks appear int he new plaster. It aso does not bond well and
just comes away.

I think the sand and cement coat is sucking all the water from the new
plaster.

Whats the soloution. Removing the sand and cement coat is not an
option at the moment.

Thanks

Bhupesh

You should paint on PVA just before plastering. The PVA should still
be a bit sticky as you apply the finish. I would also paint a dilute
coat of PVA on the day before to reduce the suction.

bp wrote:

I think the sand and cement coat is sucking all the water from the new
plaster.

Yup, played that game!

Dilute PVA (about 1 part glue to 4 water ought to be enough), apply a
generous coat will a roller, and plaster straight onto it. That ought to
stop the wall sucking out.



--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

OK,

I have followed the advice of the postings here. This is what I did:

PVA diluted and applies 24 hours beforehand. Then when ready to
plaster I apply PVS neat to the wall, waited to get sticky then
plastered on top.



I still see the plaster cracking. About 30 mins after, I see the
plaster cracking.

What am I doing wrong. Could it be that the area I am plastering is
too small for the type of plaster that I am using. I am using
Finishing plaster. The areas I am plaster are mostly small. The
largest is about the size of a tea saucer. There are about 3/4 of
those and the rest is at ground level where the top coat has come away
when removing the skirting. There are also lots of small holes (a few
inches square), where the dado rail was glued onto the wall.

There is cracking in all of the holes

I have never done plastering before, this is my first attempt. Should
I be using filler instead of plaster?

Many Thanks

BHupesh

bp wrote:

OK,

I have followed the advice of the postings here. This is what I did:

PVA diluted and applies 24 hours beforehand.

Diluted by how much? 1 pva: 4 water is about right.

Then when ready to
plaster I apply PVS neat to the wall

PVS? If you mean pva, don't use it neat. You shouldn't need this step at all

, waited to get sticky then
plastered on top.



I still see the plaster cracking. About 30 mins after, I see the
plaster cracking.

If it's cracking after 30 mins, I'd say you haven't used enough water in
the mix.

What am I doing wrong. Could it be that the area I am plastering is
too small for the type of plaster that I am using. I am using
Finishing plaster. The areas I am plaster are mostly small. The
largest is about the size of a tea saucer. There are about 3/4 of
those and the rest is at ground level where the top coat has come away
when removing the skirting. There are also lots of small holes (a few
inches square), where the dado rail was glued onto the wall.

There is cracking in all of the holes

I have never done plastering before, this is my first attempt. Should
I be using filler instead of plaster?

I would leave what you've done to dry. It's nearly always a 3 day process

Day1: Pva as above. Fill the hole with whatever plaster you have lying
around and get it level with the wall. Run something straight across the
hole to make sure it's not proud of the surface, but don't fuss over it.

Day2: Run the back of a hand saw or similar over the hole to knock off
any bits and pieces of plaster. Use a plasterers trowel to skim the
surface with filler. Don't worry about getting it all round the hole as
long as it's flat and smooth.

Day 3: Sand it smooth. If you've done stage 2 well, you may not even
need this.

bp wrote:

I have followed the advice of the postings here. This is what I did:

PVA diluted and applies 24 hours beforehand. Then when ready to
plaster I apply PVS neat to the wall, waited to get sticky then
plastered on top.

You could give the wall a good spray with water first if it is really
absorbant. Then 1:4 PVA, then plaster. Use MultiFinish plaster (not
finish or board finish) as it is better on high suction backgrounds.

Mix it to a wet consistency - like softly whipped cream, so that it just
about avoids sliding off your trowel when you turn it upright.

Don't over work it - apply smooth it a bit and then wait until it starts
to go off. polish a little bit and then leave alone again. Wait until it
dries more. For a final polish splash with a little water first.


Finishing plaster. The areas I am plaster are mostly small. The
largest is about the size of a tea saucer. There are about 3/4 of

You may be better off with polyfiller for that size.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article om,
bp writes:


OK,

I have followed the advice of the postings here. This is what I did:

PVA diluted and applies 24 hours beforehand. Then when ready to
plaster I apply PVS neat to the wall, waited to get sticky then
plastered on top.



I still see the plaster cracking. About 30 mins after, I see the
plaster cracking.

What am I doing wrong. Could it be that the area I am plastering is
too small for the type of plaster that I am using. I am using
Finishing plaster. The areas I am plaster are mostly small. The
largest is about the size of a tea saucer. There are about 3/4 of
those and the rest is at ground level where the top coat has come away
when removing the skirting. There are also lots of small holes (a few
inches square), where the dado rail was glued onto the wall.

There is cracking in all of the holes

I have never done plastering before, this is my first attempt. Should
I be using filler instead of plaster?

They are a bit small. Plaster is difficult to use in small areas.

Finish coat shrinks as it sets. You should have something like
1 - 2mm thickness, in which case it shrinks by getting thinner.
Any more than that and it may also shrink by cracking. If you need
to apply more than this, do one coat which brings you to 1mm short
of the final surface (doesn't matter if that cracks -- it provides
more key for the finish coat), and when this has nearly set but is
still wet, apply the finish coat.

When you mix it up, it should be very sloppy. A dollop on a trowel
should run off if you hold the trowel face vertical. If you are
using it as a filler (i.e. for deeper holes), you'll need to mix
that up thicker, as it will otherwise fall out. Finish coat doesn't
make a good filler, but it can be handy to avoid getting a bag of
something else as well. However, it must be sloppy/running for
the finial finish coat.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
(Andrew Gabriel) writes:
When you mix it up, it should be very sloppy. A dollop on a trowel
should run off if you hold the trowel face vertical. If you are
using it as a filler (i.e. for deeper holes), you'll need to mix
that up thicker, as it will otherwise fall out. Finish coat doesn't
make a good filler, but it can be handy to avoid getting a bag of
something else as well. However, it must be sloppy/running for
the finial finish coat.

One other thought -- you might have a sand and cement scratch
(under) coat to provide a moisture barrier. In this case you
mustn't fill holes in it with gypsum plaster, as that will
wick water straight through from the back.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]