Mist coat not adhering

Discussion in 'Painters' Talk' started by TheScruffy, Oct 24, 2021.

  1. TheScruffy

    TheScruffy Member

    It was the Dulux retail with the dog for the mist coat…..
  2. DIYDave.

    DIYDave. Screwfix Select

    This detail is partially irrelevant tbh

    Main point of detail is NO vinyl when using emulsion as a mist coat

    This topic of a mist coat comes up on the forum frequently and is like the proverbial ‘more than 1 way to skin a cat’ argument

    You could argue use whatever works for you but for me, I’ve used nothing more than Trade Matt Emuluson (usually 10lt bucket from Leyland) over plastered walls in two houses and several rooms in sisters/mums house with good results

    Don’t get hung up about exact paint/water ratios - I just mix in water to obtain a ‘single cream’ consistent - it pours off the mixing stick in a nice steady stream basically

    Overpainted with all types of emulsion over the years, different brands, Trade / Contract / washable / etc, all with no problems

    Only time I’ve had an issue is from the plasterer spraying PVA all over the walls which badly effects the mist coat and causes grief (not the fault of the mist coat however)

    As you’ve used a Vinyl Emulsion as the mist, this has likely caused the issues above

    Wayners will sort you out
    Astra ‘jumped ship’ some time ago
  3. BillyT

    BillyT Member

    Your problem is probably pva in the plaster of it has been polished too much.
    Vinyl matt/silk watered down 5-1 is perfectly fine for a mist coat providing the plaster is fully dry. The only time you would use contract matt is if plaster is still drying out.
  4. TheScruffy

    TheScruffy Member

    Thank you both for taking the time to reply.

    i will avoid vinyl from here on for mist coat. I can see now why it might cause problems. In addition the plaster was so polished it was a like a mirror finish.

    To get around the problem I’ve started putting on Zinsser BIN in an attempt to bind and seal the original mist coat. The plaster is still very thirsty despite the emulsion mist coat. It’s like it didn’t soak in properly.

    let’s hope the Zinsser does it’s job
  5. TheScruffy

    TheScruffy Member

  6. TheScruffy

    TheScruffy Member

    As you can see this was looking up the stairs before the mist coat.

    Quite the shine!
  7. Adamfya

    Adamfya Screwfix Select

    Probably best to rough the walls up a bit before the mist coat, light rub over with some 120 or 180 grit, provide a key for the paint....expect your roller was skidding all over the place...?
  8. DIYDave.

    DIYDave. Screwfix Select

    ‘plaster still very thirsty, it’s like it didn’t soak in properly’

    And that is exactly the problem you have right now

    Over polished plaster that seals the pores of the plaster, making the mist coat work harder to soak in like it should do, combined with vinyl in the mist coat emulsion, which tends to sit on the surface of the plaster and not fully soak in

    BIN is a great product and has several uses, no ideas in this situation though as any further topcoats are only as good as the first coat that should be bonded / soaked into plaster for full adhesion

    Good luck though, hope you manage to pull it off :)
  9. TheScruffy

    TheScruffy Member

    Thank you for all your advice

    I just hope Zinsser BIN has soaked in and has bound it altogether!

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