Watered down mis coat turns to powder

[ashthekid]

Hi,

 

I’m painting the first coat on a freshly plastered wall and have been using a cheap Wickes Matt emulsion white paint that I’m watering down roughly 50/50 so it absorbs nicely into the fresh plaster like I normally do but I’ve noticed after a very short time later, when I rub my hand over the surface, I get a hell of a lot of powder seeming like it comes off on my hand. I’d go as far as to say I reckon if I rubbed a wet cloth over it the paint would come completely off. I have not tested this theory though. 
 

Have I done something wrong?

Is this normal for powder to come off?

Is this going to affect the top coat layer staying or sticking on?

 

ps. The plaster is completely dry in case anyone is curious. 

[PeterW]

Scrap the mist coat, buy Super Leytex and do your base coat with that. 

[Nickfromwales]

Are people still watering paint down?  

Leyland paint from Screwfix / B&Q etc will sort this. It's specific to new plaster and "high opacity" for maximum 'obliteration'.

I've used this for year now, and 2 coats in the same day on new plaster leaves you a surface that looks like its had 3 or 4. The secret is not to use a labourer who thinks hes paying for the paint to apply it !! Get plenty on the roller, and apply it nice straight lines in rapid succession, overlapping and back-rolling ass you go to ensure that you leave no tram lines behind you. 

[joe90]

+1 to Nick, I used this and got good results https://www.screwfix.com/p/no-nonsense-bare-plaster-paint-white-10ltr/373gt

[SteamyTea]

Back in the 1980s, a friend's Father was a chemist for ICI/Dulux.

He said to put paint on as thick as practically possible because they were designed to be applied like that.

Shame I have lost contact with my mate who worked for International Paints.  He was a useful contact when problems arose.

[dpmiller]

1 hour ago, joe90 said:

+1 to Nick, I used this and got good results https://www.screwfix.com/p/no-nonsense-bare-plaster-paint-white-10ltr/373gt

 

yep, great stuff, no hassle to use.

[ashthekid]

They’ve discontinued that product apparently. And sadly I’ve been told by a couple of experienced decorators that you still needed to water it down weirdly. 
 

Any more thoughts on this powder I’m experiencing?

Just spoke to another decorator who said it’s totally normal and to be expected which is good and that he always sands down the mud coat to get rid of any imperfections and then the top coat takes nicely. 

[Bonner]

Powder is insoluble solids left after the all the liquid has been sucked in the plaster. Should just rub off.

[Nickfromwales]

18 hours ago, ashthekid said:

They’ve discontinued that product apparently. And sadly I’ve been told by a couple of experienced decorators that you still needed to water it down weirdly. 
 

Any more thoughts on this powder I’m experiencing?

Just spoke to another decorator who said it’s totally normal and to be expected which is good and that he always sands down the mud coat to get rid of any imperfections and then the top coat takes nicely. 

Buy a 10L tub, roller a trial wall yourself, see for yourself  

[Nickfromwales]

18 hours ago, ashthekid said:

Any more thoughts on this powder I’m experiencing?

 

On 26/05/2022 at 00:01, ashthekid said:

a cheap Wickes Matt emulsion white paint that I’m watering down roughly 50/50

 . Way too much water, so there's nowt left of the paint. That's why it's failing and the surface is powdery. Rub the wall down gently with an old towel and start again.

[SteamyTea]

13 hours ago, Bonner said:

Powder is insoluble solids

Titanium Dioxide usually.

[jayc89]

Our plasterer also told us to use 50/50 whitewash. Didn't cause any problems, but this is useful to know.

[Temp]

On 26/05/2022 at 00:01, ashthekid said:

I reckon if I rubbed a wet cloth over it the paint would come completely off. I have not tested this theory though. 

 

Not all emulsion is waterproof and yes we have tested this. Fortunately we found an identical colour that is washable so have painted that around light switches.