I have now skimmed a few walls but have just done a couple of bigger ones in a hallway with a window at one end. I thought they looked pretty good and my technique was getting better until I mist coated them. Now I can see loads of trowel marks that I couldn't see before - especially when the sun is coming through the window. How can I avoid these or what am I doing wrong? I couldn't see them before I painted. Just spend a few hours with a sander trying to rectify. Not sure if it will fix it or just make it worse - will see tomorrow when the paint drys and the light is on it again. Either way - I have to stop this happening or it's too time consuming and I'll have to get a pro in.
beginner help please !
- Thread starter tireetim
- Start date
You'll have to look more closely at the wall as you go when troweling up. It can also be a good thing plastering a wall with the light on it, it shows up things as you're going over it.
It's not a good idea to use a sander or sandpaper on a plastered wall. Give it a mist coart,and if you see blemishes in the plaster, use a drop of "ready mix" and a flexible scraper, and just go over each blemish with a bit,, nothing fancy, just scrape a bit of ready mix on, and scrape it off again, enough to finish off each blemish. Let it dry then give it a "very light" rub over with a 150 or 180 grit sandpaper.
So to re-cap, mist coat all the walls first, flush off any blemishes with ready mix, then lightly sand.
It's not a good idea to use a sander or sandpaper on a plastered wall. Give it a mist coart,and if you see blemishes in the plaster, use a drop of "ready mix" and a flexible scraper, and just go over each blemish with a bit,, nothing fancy, just scrape a bit of ready mix on, and scrape it off again, enough to finish off each blemish. Let it dry then give it a "very light" rub over with a 150 or 180 grit sandpaper.
So to re-cap, mist coat all the walls first, flush off any blemishes with ready mix, then lightly sand.
Thanks roughcaster. I remember it was poor light when I skimmed the wall so I will remember not to do that again. I did think about filling rather than sanding but it looked like some of the marks were raised rather then hollows. Almost like the edges of the trowel had dug in and pushed out the plaster a little. Probably just need more practice on some smaller walls where I'm not so rushed.
One other question - my house needs re-wiring and it should get done before the majority of the plastering but if the sparky needs to chase in some cables on walls that I have already done will it be possible to hide where he has cut (blend the filled bit into the wall) ? The plan is to just paint the plaster (no backing paper) so it would need to be pretty seamless.
Thanks.
Thanks.
Better chasing for cables before plastering as you said Tim. If you do have to chase into a newly plastered wall, b very careful you don't loosen the surrounding plaster. Better cutting deep into the plaster with a sharp Stanley knife first, then gently chip out the plaster as you go, making sure the chases are deep enough to cover the conduits/cables. When the cables etc are fitted into the chase, give the chased area itself good damp down/pva, then fill it out with bonding coat,, it might even need 2 coats to bring it out. Keep the wall surface either side of the chase clean too. When the b/coat has set, scrape back the plaster a ml or 2, to allow for a thin coat of multi, making sure you keep it tight so as not to cause a bump. Done carefuly, you should get an invisible, flush repair.
Another thing Tim, if you do get slight differences between the chased/patched areas of plaster, again, mist coat first, then fine tune it with the ready mix as we said earlier, then sand down.
Sometimes, a light can be "too bright" for plastering,,, and painting. I use a small portable 120w halogen work light which is perfect for me, and i also have a single 100w ordinary pearl light bulb in a holder,which i sometimes hold close to the ceiling/wall, or clip onto my steps, to highlight any blemishes/nicks towelmarks etc in the plaster, The best light to plaster in is daylight, which is obvious, but as the daylight fades, maybe a dark cloudy day , i'll use either of these lights. Another good way to spot marks in a wall as you said earlier, is when the sun is shining along a wall. If that happens while you're trowelling up a wall, that's a good thing because you'll see things as you go, but if you don't see them, it'll show up blemishes the nex day. Although i do use the portable 120w halogen work light early on, the single 100w pearl light bulb in a holder is the one i prefer to use close up to the wall/ceiling, in the final stages of trowelling once the daylight starts to fade.
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