Just had another go at plastering a wall at the weekend. In general things
went ok, thanks to all the tips that I have picked up from this Newsgroup,
but I think that I can do better with the final finish.
When I use large sweeping arc movements , I tend to leave what look like
tiny fold marks at the beginning or end of the sweep
Is this due to the speed factor, eg moving too slowly when starting and
finishing the sweep ? or is it trowel movement ?
Would I be better doing straight horizontal or vertical lines ?
Maybe I am holding the trowel at the wrong angle. Should I hold the trowel
as near as flat as possible to the wall ?
I would be most grateful for any suggestions as to how I can improve my
Are you using a "Derby" to finish off with?.
Plastering,especially large scale plastering is a thing learned by
experience and practice. It can be helped greatly with good
preparation,good technique and tools and most crucially,the right
I am not using a darby to finish off with. I have applied 2 coats of
MultiFinish, putting the second coat on before the first has completely gone
I am following the general instruction - "Put the first coat on, wash tools,
have a cup of tea, stand back and admire work", by which point it is tiime
to go back to the start and put the second coat on.
I think that my prep is ok. I have PVAd the wall a few times with a 1:5
solution, applying the plaster while the 1:3 solution is a bit tacky.
I have a Marshalltown trowel, so I can't blame that either !!!
I obviously need lots more practice
I'm not sure I know what you mean.
If you mean vibration marks, that often happens. When you have
finished they can be very visible, but if you polished off
correctly, you won't be able to feel them at all, so they should
completely vanish when you decorate.
You may not have wet the surface enough when polishing -- you
should be dragging a small quantity of water along the surface
with the trowel edge. This carries fine plaster particles which
are broken off the peaks by the trowel edge and deposits them
in any depressions, which is how the polishing works. Flick
water over the surface with a large brush (or used a plant
sprayer) before you draw the trowel across.
The trowel may be too new -- i.e. not worn in enough.
Plastering is much easier using some rusty old used trowel you
dig out of the garden shed (providing you can polish it up along
the edges) than by using a new trowel. Traditionally, a plasterer
would buy a new trowel and give it to a renderer for a few weeks
to break it in and wear off the sharp corners, before taking it
back and using it for real plasterwork. You can use a house
brick with a good flat face as a grinding stone to polish up the
edges and take off the sharp corners. Do this by trying to saw
through the brick face with the trowel edge at an angle of around
30 degrees. This can also be used to repair a trowel if you manage
to put a nic in the polishing edge.
I've never used a "Derby", but I think it's for creating a flat
scratch coat (which I do with a straight edged piece of timber),
not for polishing finish coat.
Yes, I think they are vibration marks. They are difficult to remove
I think I have not polished it enough. I was a bit knackered at that stage
and only wet the wall in places
where it didn't look to have a smooth finish.
I gather from your comments that I need to wet the complete wall as I polish
Sometimes when I make a large sweeps I accidentally dig the corner of the
trowel into the plaster
as I nearing the end of the sweep. I think that I should have bought a
slightly shorter trowel
Should I try to take the off the sharp rectangular corner ie make it more
The sides of the trowel are very sharp. I managed to put a nice nick in my
when hastily cleaning it.
Don't sweat it, the finished job can be repaired with some polyfiller.
The main thing is you had a go and it turned out OK. You were not
expecting perfection first time were you? How did you get on with the
If you reckon to go over a wall with six trowellings you will find the
last stage works the magic getting all those bumps out. Twice when you
put the finish on, twice when you get the air bubbles out and twice when
you polish it.
You just keep on as you are. The problem was in the newness of both you
and the trowel. Next time eh?
As you sweep over the wall the arc you describe covers most of the
previous sweep the next covers most of your last and so on. In this way
each blemish is worked out and smoothed away.
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I looked at B&Q for one ot those maids that you mentioned, but they were
out of stock !!!
I am getting plenty of practise (Not maid ravishing !!) as I have done
quite a bit of patching on the walls with bonding, and now putting two
coats of plaster on each wall.
I might even be brave enough to tackle a ceiling one day..
I will definitely have arms like popeye when I am finished. Six
that's a fair few cups ot tea...
As they say "practice makes perfect"
Better tackle another wall then !!
Strangely enough I found the ceiling easier than the walls. I did a
plastering evening class and we did ceilings after a few weeks of walls. A
couple of things to watch out for though - try and have some long planks to
plaster from - it really helps to be able to move without having to keep
moving stepladders - and wear glasses! Halfway through my first ceiling a I
dropped a great lump in my eye. Cue rush to sink to rinse out and then a
very red/scratched eye for a few days.
Goods news if you found ceilings easier than walls.
How long did your course last ?
I presume that 1 coat would be enough on plasterboard. ?
Do you use Board Finish or MultiFinish for ceilings ?
Somebody suggested using MultiFinish as it takes longer to go off
I am using planks for the top of the walls as it is too much hassle moving
I haven't managed to get it in my eyes yet, but it seems to have gone
just about every where else!!
I suspect that your last trowelling is being done too early. Wait
until the mortar has gone off a bit more so there is plenty of
resistance to your trowel then spray with water before each stroke to
provide a slippery surface. Press hard. Then run a damp paintbrush
over the surface. That will remove any shinily overtrowelled areas and
stop the decorator cursing you later
~~ Anna Kettle, Suffolk, England
|""""| ~ Plaster conservation and lime plaster repair
/ ^^ \ // Freehand modelling in lime: overmantels, pargeting etc
|____| www.kettlenet.co.uk 01359 230642
With redards to the arc sweeping motion. I understand that the
trailing edge of the trowel is in contact with the plaster as your arm
goes up but what edge is in contact with the plaster on the way down?
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