Problem painting over silk emulsion walls and colour change

Discussion in 'Painters' Talk' started by DIYDave, Aug 6, 2013.

  1. DIYDave

    DIYDave Guest

    Hi all and I'm after some advice from you kind folks, please and thank you !

    Myself and another dad have volunteered some spare time to paint a couple of rooms at our boys youth club
    Doesn't need to be a perfect job but to freshen up the rooms and get them looking semi decent
    Budget is just slightly above zero and as above, labour has been volunteered !

    One room is at present a pale blue and the other a rusty colour, both looking like painted with vinyl silk
    The youth club seem to like the silk paint is it's washable and doesn't mark and have asked that both rooms are painted in white vinyl silk

    I thought that as going for a colour change to white, an extra coat would probably be needed
    What I didn't know was that trying to paint over the existing silk would be such a problem to obliterate the colour underneath
    Washed the walls down with a sugar soap solution and rinsed with clean water

    Started off using Wickes Trade Silk as had some at home (but don't remember ever using it). After 2 coats gave up as there was no coverage at all
    Then used Leyland Trade Contract Silk, after 3 coats again gave up as the coverage didn't seem to be improving after each coat
    Today was recommended Johnson's Trade Vinyl Silk and got 2 coats on. Coverage seems a little better than other paints but still the blue is showing through, probably 4 coats would cover ?

    I'm a bit fed up obviously as I don't mind giving up some of my time but this is now dragging on and as I've started, I feel that I should complete the job
    The other guy that is helping has no decorating experience but is a helpful pair of hands and is willing to see this through as well

    So any advice please that you can offer would really make my life easier (and my limited spare time)
     
  2. tremain

    tremain New Member

    Hi Dave,a quick and cheap solution would to be sand the existing coat of silk ,then apply 1 or 2 coats of contact matt emulsion to obliterate the previous colour then finish with 2 coats of silk of choice.This is not without risk as you may get some crazing(cracks in paint) but it would be worth a go on a budget of time and money.
     
  3. DIYDave

    DIYDave Guest

    Thank you tremain for your quick response and advice
    Will give the walls and sand as suggested, I have a pole sander and would guess say 120 grit paper ?

    Some months ago  I was painting plaster coving with matt emulsion, but this was over previous silk
    The matt took ages to dry and caused the silk to bubble and blister in loads of places

    I went into my local Dulux Decorator Centre for paint and advice and was told that this is the usual problem with painting matt over silk
    The silk is almost impervious so the matt sits on top, stays wet for ages and the water in the matt then causes the silk to blister

    Can try a small area on one wall but have you seen this problem before ?
    I know you mentioned possible crazing

    This silk paint is a real pain and is horrible to paint with
    Do many people still use it ?
    Seems old fashioned to me

    Thanks again tremain
     
  4. Goodwill

    Goodwill Member

    Hi Dave,  Am I reading you correctly, you have applied seven coats of vinyl silk emulsion from three manufacturers and you still have not obliterated the original respective colours?

    I must admit I'm not generally very fond of vinyl silk emulsion.  What you think is a standard vinyl silk may be something like Dulux Diamond Eggshell.  I trust you gave these walls an appropriate rubbing down for an effective key. 

    However, when going for a marked change in colour I block out the whole surface with a light grey followed by at least two coats of the finishing colour.  The light grey gives the obliteration a good start.  

    Also, pay attention to your cutting in and rolling technique, one of you could keep ahead of the other with the cutting in whilst the other one rolls the paint on employing an elongated W.  Use a pole with your roller and make your application from the bottom to the top then back to the bottom in single sweeps (depending on the height).  Charge the sleeve evenly and commence a sleeve's width from the corner, or the end of the wall, then work back onto this strip before moving on.  Your starting pressure should light then increase it to be firm in order to spread the paint evenly.  Don't forget to lay-off lightly with the finishing strokes, be progressive.
     
  5. tremain

    tremain New Member

    Yeah Dave you can come across problems with matt over silk,but got to be worth a try in your circumstance.The bubbling problem tends to occur mainly on coving so you may be alright in that regard.
    I have to do this quite often,today as it happens covering a strong purple and more often than not it works.
    Silk is'nt so popular nowadays ,vinyl matt being often preferred, your right .
     
  6. DIYDave

    DIYDave Guest

    Hi Goodwill and many thanks for your reply

    Just to clarify, I have tried three makes of paint on three different walls
    The paint with the best obliterating quality so far has been the Johnson's, although after 2 coats the wall definitely needs a third coat and I'm thinking a possible forth

    The existing coloured paint on the walls has a plastic feel to it and a high sheen, so I was assuming a vinyl silk had been used and that's what the manager told me at the youth club

    When you say you use a light grey for a marked colour change is that an undercoat or grey emulsion
    As I'm planning on painting silk over silk would I need to use grey silk emulsion then

    I've done a lot of painting at home at diy level, roller and pole on walls and ceilings and I've achieved a standard that I'm well happy with  but thank you for all the added tips anyway
    I certainly realise that there's more to splashing paint on the walls than meets the eye !

    To be honest though I didn't sand down the walls before painting -  Just a wash down with sugar soap
    Walls were actually in good condition, very little filling required so sanding down didn't even cross my mind
    Could this be a large cause of the problem ?? Pole sander and 120 grit sounds about right ??

    Thank you again Goodwill
     
  7. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Matt white(or light grey) undercoat.

    Mr. HandyAndy - Really
     
  8. surfermick

    surfermick New Member

    seconded,that will sort it for sure.
     
  9. DIYDave

    DIYDave Guest

    Hi again guys and thanks for all the advice given

    I popped into the club after work today to try out the matt emulsion trick
    Sanded over a 1 mtr square with 120 paper and wiped down
    Rollered over a coat of white matt emulsion
    Grabbed a coffee and left wall for 30-40 mins
    Checked the wall and the area with the matt white emulsion had several blisters on it where the silk had lifted from the plaster surface

    Now really fed up - Grrrrrr

    As with my 2nd post, i had this problem before when painting over plaster coving coated in silk, then changing to matt emulsion. This too caused blisters in the silk underneath

    Looking at the grey undercoat idea but worried that this too will blister
    Are you talking about a solvent based or water based undercoat -  a specific product if possible please

    Thanks for the continued help with this - a wont be able to go back until the weekend now so really need a solution in hand
     
  10. tremain

    tremain New Member

    Hi ,it's not that it silk or matt it is because the plaster was'nt sealed /primed properly in the first place .The moisture in the new paint lifting the old paint because it never really adhered.Might be worth trying an solvent based undercoat now.
    P.s. zinsser bullseye might work but pricey.
     
  11. Goodwill

    Goodwill Member

    If using Zinsser then the solvent-based version of AllCoat would probably do the job best. Primer/Sealer, stain-blocker (including dark colours) and finish as it's durable and washable.   Likely to use fewer coats than vinyl silk, although coverage is slightly lower.  Prefer to use a mohair sleeve and good ventilation is essential.  Don't use the water-based version, you are likely to get the same problem with the blistering.
     
  12. tremain

    tremain New Member

    Your right about tne zinsser Goodwill,it was my hasty p.s.,I stand corrected
     
  13. Goodwill

    Goodwill Member

    Hi Tremain, Thanks for your confirmation.  Here's hoping Dave and his mate get it right.
     
  14. tremain

    tremain New Member

    A pleasure Goodwill....and indeed, the youth need their club ! :)
     
  15. DIYDave

    DIYDave Guest

    Thanks very much to you all for the continued advice given

    I'm up for some friendly banter on most occasions but when you need some helpful advice and pronto..............And when the forum works......... Its brilliant !! (and appreciated)

    Going to try a solvent based undercoat next on a patch of wall that will be covered by a notice board
    Hopefully popping in tomorrow but see how time goes - Sunday at a wedding and that's another weekend over and done with, so may have to be one evening during the week

    Will report back on the progress, many thanks
     

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