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 finish
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 mix/consistency..
Joe 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 off. 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.
No.
No. 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 it.
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 for practicing. Should I try to take the off the sharp rectangular corner ie make it more round ? The sides of the trowel are very sharp. I managed to put a nice nick in my finger 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 maid ravishing?
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.
have bought a
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.
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 trowellings - 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 stepladders. 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
~~ Anna Kettle, Suffolk, England |""""| ~ Plaster conservation and lime plaster repair / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____|
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?
Always trailing edge, or you'll dig into the plaster. You can't sweep down until the plaster is reasonably well gone off, or your'll just pull the plaster off the wall.
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