Plastering over paint

Discussion in 'Building' started by Mick Leek, 6 Dec 2005.

  1. Mick Leek

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    Ok Legs, Here is one for you :D

    I know you will be here somewhere. I intend patching a wall in a VERY old house. It appears that the scratch coat is render rather than plaster (very hard and course) and that seems quite solid.

    The finish coat is coming away in patches here and there and the remainder has about 4 coats of paint (probably Emulsion) I want to patch the bits where the finish is coming away and then skim over the entire wall.

    My question is, Do i fill first then skim OR because its only the top coat that has come away, can i do it all in one go ?

    Do i have to do anything to prep the painted surface ? as in rough it up a little with sand paper or just go for it?

    I have plastered a few walls over the last few months without a problem, but i have never attempted plastering over a painted surface.

    Cheers in advance,

    By the way, PLEASE PLEASE PLEASE can you answer the question before you get into a debate with JB Bonding He He :eek: :eek:

    Thanks

    Mick
     
  2. jbonding

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    ill answer it first and see what he says,if any of the backing is loose remove and fill before skimming, get a decent scraper on the wall and remove any loose paint, pva the wall 3-1 depending on the quality of the pva to kill any suction, let it dry.pva again and skim once its tacky, if its a gloss or vinle silk, scratching the surface will also provide a mechanical key so thats 2 keys so its better.
     
  3. Mick Leek

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    Cheers Jbonding...

    Thanks for that... If the wall is already painted surely there would be no need to seal it with PVA to prevent suction ? apart from the new areas.....

    Would i fill the missing top coat with multi finish ? them skim it over ?

    Thanks
     
  4. jbonding

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    the first coat of pva evens out the suction on the whole wall, fill out the bits, ruff the whole wall then lay it down and away you go.
     
  5. Mick Leek

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    Cheers for that,

    Just a quick question. I suppose that if you have been plastering as long as you guys then this next question will sound pretty silly but here goes.

    I'm not the best DIY plasterer and certainly not the worst. I occassionaly struggle to get the base coat level without dips and hollows, i use my spirit level and kind of drag along to level.
    I have heard of feather edges and also darby's

    are these the same and do you guys use them ?

    would it be advisable to get one ?

    I have already bought marshall town floats and brick laying trowels along with other quality tools. I thought what i would save on employing people would mean i can buy quality tools to do the job. A couple of friends were that impressed with my work, they have asked me to skim there walls. (Rewarded with beer vouchers)

    I just want to make sure i do as good a job as i can and so if a feather edge or darby will help then i will get one.

    Thanks Guys

    Mick.
     
  6. jbonding

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    a feather edge is a long straight edge in various lengths. My feather edge is just under 8 foot and there superb for floating once you learn how to use it. It can be used for a number of things as a straight edge. a darby is about 3 foot long and has two handles and is used for smoothing a wall over after youve used your straight edge, once you are good with a darby this can be used in the same way as a straight edge and a good plasterer can get a big wall just as flat with a darby. years ago i swore by my darby but now i prefer a straight edge. be carefull getting paid in beer vouchers the news might get out,lol. i would say get a straight edge first and get used to it before getting a darby, a bit more skill is needed with a darby.
     
  7. Mick Leek

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    Hi Jbonding

    So basically apply bonding coat to wall then use feather edge to scrape down to see any hollows and such, Then once level, float up. Or is the edge just simply used to see the hollows then filled in ?

    Thanks,

    Its great when someone actually explains it to you.
     
  8. jbonding

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    like what you said, fill the hollows and go over again with the feather edge.if your floating and your right handed start from right to left. run the straight edge across and up making sure your skirting and ceiling line are flat, dont worry about level unless its a column, reveal or beam.
     
  9. Mick Leek

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    So you dont actually use the feather edge to revove any of the plaster ?

    Just to see hollows ? If that is the case, then what i am doing with my 1.2 meter spirit level is the same as the feather edge, although i do remove a bit of plaster with that and kind of scrape the surface.

    Thanks, I am rendering a wall on sat then skimming the room on sunday so i will take a piccie and see what you think :)

    Am I ok to skim over the base the following day ?

    Mick
     
  10. joe-90

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    I used to know a guy that used to get his lad to load his darby while he held it and then used it as a very large float to apply the plaster. He used to get a very flat wall.

    BTW for what it's worth I rate JBs posts very highly. I've never known him to give out duff info.

    One quick question JB - how do you decide when it is the right time to go back to the stuff you've slapped on earlier to give it the smoothing treatment? I'm always interested in fine tuning my style.


    joe
     
  11. jbonding

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    alright joe are you on about finish? it all depends on the background,weather and amount i put on, if i put on two bags or three i turn back and lay down straight away, then flatten and trowel. The less you play with it trying to get the lines out in your roughing on or laying down coat the better, the flattening coat does this, in time there will be less trowel marks and you have plenty of time to keep on top.its hard to explain exactly when to jump back on it but this comes with experience.
     
  12. Mick Leek

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    Now im really lost?

    Could you explain in thick T**T who knows nowt about plastering trying to learn terms :D

    Laying down Flatting down ? trowel ?

    Ok here is how i do it. bond wall or render use level and fill hollows, leave overnight then skim. leave 20 mins or so then polish .. that correct ?
     
  13. Mick Leek

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  14. jbonding

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    roughing on=1st coat
    laying down =2nd coat
    flattening = going over with the trowel getting out the lines
    trowel = same as above
    polish = doing the painters head in :LOL:
     
  15. jbonding

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    ?
     

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