Skimming over old plaster.
Andy Hide
perfect skim onto plasterboard but finding that old walls are much
more difficult. Any slight lumps and bumps mean that the you are more
likely to miss bits when trying to get a good finish.
I primed the surface first with PVA which I think helped to increase
the working time. Total thickness of the skim was about 2-3mm. Can you
go thicker than this on old walls to help cover up any imperfections ?
Applied in two coats, the second applied just as the first was
begining to set.
Also found that there were a few grit marks. Badly mixed plaster ?
When ironing out the trowel marks as the plaster is setting does
anyone have any tips on which way to work across the wall. Should you
go top to bottom or left to right? Are long sweeps, short sweeps
better ?
Any help much appreciated.
Andy.
Jet
"Andy Hide" <andy...@totalise.co.uk> wrote in message
news:8f88db3.04022...@posting.google.com...
<<snip>>
> I primed the surface first with PVA which I think helped to increase
> the working time. Total thickness of the skim was about 2-3mm. Can you
> go thicker than this on old walls to help cover up any imperfections ?
> Applied in two coats, the second applied just as the first was
> begining to set.
Done this also, but waited for the first coat of plaster to dry out. Not
always possible but it stops the second skim coat being "pushed" into the
first skim, if that makes sense.
> Also found that there were a few grit marks. Badly mixed plaster ?
Maybe a dirty bucket containing left-overs from a previous mix? It pays to
keep *all* equipment including buckets / mixing paddles spotless. I used to
use a piece of 2x2 but invested in a paddle to mix the wet stuff as its
easier to keep clean.
> When ironing out the trowel marks as the plaster is setting does
> anyone have any tips on which way to work across the wall. Should you
> go top to bottom or left to right? Are long sweeps, short sweeps
> better ?
Whatever is the comfiest. I find that at first the sweeps are longer with
greater pressure, gradually diminishing as the bumps and curves get flatter.
HOT TIP: Stellas Law :- I *NEVER* skim without at least 1 can down my neck,
then I got something to blame when SWMBO spots a flaw ;))
hth
--
Jet
all plastering done when the sun is over the yard-arm ;)
Grouch
=============================================
There's no golden rule to Plastering if you feel comfy the way You apply it
then settle for that.
One tip I can give instead of having a large pasting brush in hand to dampen
plaster as your Polishing it, use a spray bottle.
Grouch
Andy Hide
largish wall e.g. a hallway or stairs is it possible to split the job
into two sections ? Skim dries out quite quickly and I don't think I
could get a 4m wall done in time. Is there a standard technique to get
a good join between the two or is it time to call in a pro who can
work at a decent speed ?
"Grouch" <imh...@blueyonder.co.uk> wrote in message news:<GVE_b.5400$ie6....@news-binary.blueyonder.co.uk>...
JW
> largish wall e.g. a hallway or stairs is it possible to split the job
> into two sections ? Skim dries out quite quickly and I don't think I
> could get a 4m wall done in time. Is there a standard technique to get
> a good join between the two or is it time to call in a pro who can
> work at a decent speed ?
>
give yourself a bit more time.
If you start at one end & as you work across, you'll find you're skimming
one area whilst polishing another. You'll need someone to mix as you will be
quite busy working the plaster.
Give it a try. If it ends up a mess, you can always get a plasterer in to
skim over it.
As Grouch said, use a spray bottle. The 1 ltr garden sprays are ideal.
JW
Grouch
> largish wall e.g. a hallway or stairs is it possible to split the job
> into two sections ? Skim dries out quite quickly and I don't think I
> could get a 4m wall done in time. Is there a standard technique to get
> a good join between the two or is it time to call in a pro who can
> work at a decent speed ?
>
=================================================
Get your Missus to do the mixing. :o( this will give you an edge over
covering the wall in one fell swoop, make sure the Mix is sloppy try to get
in the knack of sweeping the Plaster in large sweeps, either up the wall or
across.
I'm no Master plasterer and have to Mix the stuff & apply it. Two of my
walls are ten foot high by twelve feet across when I first started I thought
Jesus! I'll have to work lig a pig but when I actually got into the swing of
it they where both done in no time. pant! :o)
I'm only 5 foot 2 inchs/9 stone. But got the stamina to tackle and finish.
Grouch
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Andrew Gabriel
andy...@totalise.co.uk (Andy Hide) writes:
> Thanks for these tips. Another question though. If you are skimming a
> largish wall e.g. a hallway or stairs is it possible to split the job
> into two sections ?
Yes. Pick a join line, plaster slightly over it, and before the
plaster has gone fully off, cut back the edge to a clean step, and
not feathered, as you can't feather in a join. If you know where the
join is, you will always be able to see it on the finished work, but
a good join won't notice unless you look for it. On many houses, you
will spot a join on the wall where the staircase is, as the plasterer
probably didn't do it in one go.
> Skim dries out quite quickly and I don't think I
> could get a 4m wall done in time.
Hum -- skim normally takes a day to dry out IME, much longer than it
takes to go off (set).
>> > Anyone have any tips for skimming onto old plaster? Managed an almost
>> > perfect skim onto plasterboard but finding that old walls are much
>> > more difficult. Any slight lumps and bumps mean that the you are more
>> > likely to miss bits when trying to get a good finish.
Remove any obvious lumps above the surface.
The first skim coat goes on normally as thin as you can but should
leave the plaster level with the most proud bumps remaining on the wall.
i.e. you tend to scrape the trowl edge over the rough surface, but it
should leave you with a flat surface. The reason for the second coat is
that you can't polish this first coat because of the background coming
to the surface in places. So the second coat is then put on ~2mm thick
to give you clearance over the most proud bumps on the background, and
that's enough to enable you to polish the surface.
>> > I primed the surface first with PVA which I think helped to increase
>> > the working time. Total thickness of the skim was about 2-3mm. Can you
>> > go thicker than this on old walls to help cover up any imperfections ?
Yes. The issue is that plaster finish coat shrinks when it sets. A thin
coat shrinks by getting slightly thinner which doesn't notice, but a
thick coat may crack.
>> > Applied in two coats, the second applied just as the first was
>> > begining to set.
>> >
>> > Also found that there were a few grit marks. Badly mixed plaster ?
Possibly. Check you aren't leaving unmixed plaster up the sides of
the bucket, only to fall in when you pour the plaster out. Other
sources of grit are from the wall (PVA should have stopped that)
or from adjacent walls/ceilings. I had fun plastering a wall up to
a ceiling artexed with small stalactites. The trowl edge would keep
breaking them off and dragging them into my plasterwork ;-)
>> > When ironing out the trowel marks as the plaster is setting does
>> > anyone have any tips on which way to work across the wall. Should you
>> > go top to bottom or left to right? Are long sweeps, short sweeps
>> > better ?
Generally inwards from all the edges. Keeping the edge of the trowl
parallel to the wall edge, start the sweep along the edge but in a
circular motion which sweeps out and ends a quarter turn later in a
direction perpendicular to the edge, but without turning the trowl.
When you aren't near an edge, it doesn't matter.
--
Andrew Gabriel
Andy Hide
coat following this method and then the second coat or are you
applying the second coat on the earlier sections as they begin to set
as you work along the wall ?
Put another way - do you have to follow the second coat quickly after
the first as you are moving along the wall or can you complete the
whole wall 1st coat and then go back and do the 2nd coat.
Hope I have made myself clear here.
Andy.
"JW" <wilb...@hotmail.com> wrote in message news:<c1mc96$btf$1...@hercules.btinternet.com>...
Andy Hide
the plaster and think you've done a great job. However, when the
plaster dries out and goes a lighter colour you see small areas (no
bigger than 10 pence piece in the worst places max) where it looks
like the plaster has not been polished up properly. I have seen this
to a lesser extent in pro's work too and can't figure how why this
happens.
This never happens to me on plaster board so I can only guess that
maybe the wall I am going over is not perfectly flat. As you polish up
with the float you are missing tiny dimples in the wall as the float
is passing over them. Anyone else come across this ? Anyone got a fix?
Andy.
and...@cucumber.demon.co.uk (Andrew Gabriel) wrote in message news:<c1o480$1sj$1...@new-usenet.uk.sun.com>...
Grouch
Bet you can't do a ceiling. lol. After the plasters dried coat the wall with
a thin mix of PVA, it helps a great deal if your Wallpapering over it.
--
Grouch