a few questions

[zippypop]

Hi there

I have just started a plastering course and am really enjoying it, but something I have read which hasnt come up in the course yet is "scoring".

Can anyone tell me what scoring means if you have to score a ceiling before plastering? Also, I know you cant plaster on MDF.....are there any other surfaces to avoid. And finally if you are stripping wallpaper, is it best to rub down, clean with sugar soap, have a clean wall, then pva, then plaster?

thanks

 

[Minh]

Welcome to the forum.

I assume that when you mention "scoring" you are referring to scratching the surface to give it a key. In general, it is only necessary to key backing plasters before applying a finishing coat plaster. When we apply a finishing coat without using a backing coat, we prepare the surface using PVA or a bonding agent such as Thistle Bond-It.

Avoid wooden backgrounds because they will move and cause the plaster to crack. With regards to wallpaper, remove, clean with sugar soap, PVA several times if necessary and then plaster when tacky

 

[Danny]

Hi Zippy

Never heard of the term scoring in plastering I always remember "Plaster on wood is no good" however if you do have to go over it ie purlins or whatever use some wire mesh and that will help it

Good luck

Danny

 

[zippypop]

thanks both

 

[zippypop]

minh

when you use the term "key" , what does that actually mean?? sorry, only been to two 90 minute classes so far, and really have learnt the basics. just want to get a better understanding

thanks in advance

 

[Danny]

a key means that you are giving the surface something to grip on to...

so a polished surface like a mirror doesnt have a key hence why its easy to clean... but something like sandpaper is very rough and so has a good key.... if that makes sense...lol