Hi, I have used Carlite bonding on the walls in a bedroom. I am now ready to skim it. If I want to do two coats of skim on a wall what is the process. Do I have to do the second coat before the first is dry or do I have to PVA before doing the second coat. Thanks
I've posted lots of articles on plastering. Below are some excerpts from one of them. Search back on Google for more articles.
When you do 2 coats onto surfaces such as a scratch (under) coat, the first coat goes on and pretty much fills in the surface bringing it all up to the level of the highest peaks on the surface. You couldn't polish this because in places it will be level with the peaks of the scratch coat. The second coat then goes on to make sure there's a layer of finish plaster over the top of all the highest peaks in the scratch coat, and this can be polished without the scratch coat peaks showing through.
You start by just getting the plaster on the wall, as evenly as possible, but ignore the trowel marks which you can't do anything about at this stage. When the plaster has gone off a little and got a bit thicker, you will be able to re-trowel the surface and produce smaller trowel marks -- if you can't, then leave it a bit longer. At each stage in the 'going off' process, you will be able to improve the surface a bit, but no more. An important part of the process is not to carry on trying to improve the surface past what is possible at any particular point in the 'going off' process -- all that can do is make it worse. You must leave it to 'go off' some more before you can improve on it any more. Constantly over working an area in an effort to try and improve it before it's ready is a very common reason for poor outcome.
You should do the next coat before the one before dries (and ideally before it completely sets, except for sand and cement which you should skim over after 24-48 hours). If you do leave a coat it until it dries, then you'll need to PVA the surface as for a reskim.
What Andrew said, but if the wall you have ready is dry, you'll need to seal it with 2 coats of PVA, the first quite strong, about 3:1, the second about
5:1, and leave about an hour between coats, then skim while the second coat is still wet.
One more question. If I use Bonding onto a wall, and I want to do another coat after the first has dried. Do I have to PVA that, or can I just put the second coat directly onto the first?? Thanks
Errr..... didn't he just answer that about 3 lines above ?????
If you do leave a coat it until it dries, >>>then you'll need to PVA the surface as for a reskim...........
Nick
I thought he was talking about applying a second skim coat. "Confused". It`s just that a plasterer told me that if I use bonding on the wall, then want to give it a second coat a couple of days latter to make it thicker, all I had to do is make sure I have scratched it then wet the surface of the first coat before applying the second.?????
Well, I have never had to use PVA, I have scratched up a surface to get a better key and never had problems, but then again it depends on definitions of "dry" and "hardened off" I suppose.... PVA depends on being able to soak in a bit and you must plaster to it whilst its still tacky, as I understand it......
Nick
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.