Coving before or after painting

Discussion in 'Painters' Talk' started by DIY_Has123, Mar 21, 2021.

  1. DIY_Has123

    DIY_Has123 Member

    Have just had walls and ceiling plastered.

    Plan to fit modern plastic polystyrene coving so must use non solvent adhesive. Hate the traditional plaster stuff too brittle to work with, polystyrene cuts easier.

    Should I put the coving onto bare plaster before mist coating and painting the walls or ceiling or all after?
  2. Wayners

    Wayners Screwfix Select

    The mastic for that cove don't like dry surfaces so you need to seal. In saying that it sometimes says one surface needs to be pourus but I've had cracking and shrinking with the adhesive.

    I have stuck some myself and I used some acrylic primer undercoat (which I use for mist coating anyway) to prime.

    If your going to use cheapo chalky contract matt too mistcoat the adhesive won't stick to that very well.

    Very thin pva and water 5-1 (D4 wood glue as you can get small bottle) will also work.

    What dose the mastic adhesive say on application to pourus surfaces?
  3. nigel willson

    nigel willson Screwfix Select

    Do it properly, poly is:(
  4. techie

    techie Active Member

    What Nigel said....
    nigel willson likes this.
  5. DIY_Has123

    DIY_Has123 Member

    I bought a few tubes of this Everbuild stuff:

    Coving supplier just says use solvent free adhesive. On the back says to prime with 4 to 1 pva and allow to dry.

    Have got about 14.5 metres of coving to put up so no idea if 3 tubes will do or not.

    I'm planning to use 2 coats of No Nonsense bare plaster paint for mist coat btw

    Can't be bothered with watering down emulsion and the mess.

    Attached Files:

  6. DIY_Has123

    DIY_Has123 Member

    Why would you say poly isn't as good as plaster coving?

    Have had poly coving put up in New kitchen extension and looks as good and as real as the original coving in some rooms of Victorian house once painted. Plus it comes primed.

    Traditional plaster coving just seems too fragile but hey happy to hear the opinion of others...
  7. DIY_Has123

    DIY_Has123 Member

  8. DIY_Has123

    DIY_Has123 Member

    Also says new plastered walls must be minimum 4 weeks old before application.

    Isn't 4 weeks just overkill?

    I mean had walls and ceiling skimmed last week and most of it is light pink fully dry apart from wall where thick bonding was applied to level out.
  9. polybear

    polybear Member

    I've just put duropolymer coving up in my kitchen
    - and used this adhesive:

    The newly-plastered walls were primed with a thinned PVA mix first (if you're gonna paint the plaster walls after coving don't get this mix on the plaster where the coving isn't going). The ceiling had previously been painted so no priming was needed.
    Looks fine, and the coving is nice to work with, takes impacts without marking like cr@p expanded polystyrene coving does, is easy to cut and work with, lightweight, and doesn't crack and break like plaster coving does - either before it goes on the wall or several years later when the house moves a bit.

    Duropolymer also flexes a bit, so if walls and/or ceiling aren't dead straight the coving will easily adjust to suit when fitting it. No brainer in my book :D
  10. Wayners

    Wayners Screwfix Select

    Drying times are overkill. Can get the cove on it when dry and normally 3 days. I paint most of what I skim a few days later no problem.

    Re paint. Some durables won't like that plaster paint. Just saying. It's really for painting over wet plaster (same day it's skimmed) or when you want to allow walls to dry out for months. It's not a primer for paint. Terrible misuse of these type of products and similar products in the UK.. Just saying. Just not that smooth of finish and no sealing properties. Still many bang on happily so Hay ho
  11. DIY_Has123

    DIY_Has123 Member

    That toolstation adhesive seems better than this eberbuild since it only covers 2m of coving, the one you used covers triple that!

    And re cr@p expanded polystyrene...we fitted this one to our extension:

    It was solid to the touch and feel yet very lightweight and easy to cut. So it would take impacts without marking whatsoever.

    Why don't I just mist coat and seal all the walls and ceiling first...wouldn't that eliminate the need for priming with PVA mix?

    The way your describing I'd have to carefully mark out the coving lines all around the room wall and ceiling and careful apply the PVA mix within the lines, that PVA mix is bound to drip lol
  12. DIY_Has123

    DIY_Has123 Member

    So Wayners when decorating a room would you prime the coving perimeter with PVA mix first then fit coving then mist coat and paint rest of room/ceiling?

    Also what would you recommend for mist coat in terms of brand/product if not this bare plaster paint? It's got really high positive reviews btw so thought I'd give it a go...
  13. DIY_Has123

    DIY_Has123 Member

  14. Wayners

    Wayners Screwfix Select


    Yeah. Go with the pva then your plaster paint. Just read what your top coat emulsion says about surfaces prep just to be safe.

    There is a good leyland technical video (skill builder). on YouTube about contract matt, vinyl matt and durable matt and what they are for and how to apply if your interested.
  15. nigel willson

    nigel willson Screwfix Select

    They are referring to whole wall plastering would imagine, but hay if you don’t follow what they say! If it’s only skim and you have good heating and ventilation, should be ok
  16. nigel willson

    nigel willson Screwfix Select

  17. DIY_Has123

    DIY_Has123 Member

    Thanks will check it out. Should I be worried about any PVA mix dripping down to the bare plaster walls or this needs to be completely avoided?
  18. DIY_Has123

    DIY_Has123 Member

    Yeah most of it is light pink now anyway after few days apart from exterior wall which had thick bonding applied to level out so maybe a couple weeks for that.
  19. DIY_Has123

    DIY_Has123 Member

    Yeah think people have many misconceptions about coving which is not plaster, because probably when plastic material coving was new it wasn't very good but its come a long way and now probably as good as the best plaster coving stuff.
  20. Wayners

    Wayners Screwfix Select

    No worries with the pva. You can run masking tape at the bottom of where cove will sit or run pencil like around and seal to that. As long as pva is 3±-1 or thiner it paints over a fine. Plenty of yourtube demos on that although some run to the hills with a just the thought.
    Pva sealing prior to emulsion is not a good idea as a general rule.

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