Painting powdery workshop floor

[Lobster]

This summer I've been steadily doing out the room attached to our garage which for years I've described as my 'workshop', but which will soon, hopefully, finally be able to live up to its name. Got it wired for power a few months ago, and at the weekend I finished painting the inside white, so I'll be able to see what I'm doing out there. (SWMBO put her head round the door - "Blimey, it's so bright in here now, I won't be able to come in" - "Hah! RESULT!!" I didn't say.

Anyway, I digress.

Last stage for now is painting the concrete floor, with

The floor was laid about 10 years ago, and all that time has been covered by an old carpet, so it's very clean underneath that. However, it's very dusty, and other than vaccuuming, what should I be doing before applying paint? I'm concerned that applying a coat of PVA or something will make it non-stick-ish, so the paint won't adhere properly (having experienced exactly that phenomenon with emulsion paint on fresh, PVA-treated plaster...)

What's the best answer for this?

Thanks David

[Phil L]

Brush it thoroughly, run the vacuum over it, taking care to get in the corners, then paint it. Anything you put down prior to the paint will stop it adhering

[ss]

I was advised when I done mine to give it 2 coats the first one thinned down and the second at full strength. Dunno how true it is but it lasted 12 years and then I sold the house.

[Phil L]

Yeah two coats is recomended on bare concrete...it's usually a case of 'suck it and see'. If it looks good after one, the second one is optional :-)

[Lobster]

Would a dilute 'piss-coat' first be a good idea (ie as used when painting virgin plaster?)

Dvaid

[Lobster]

Just wondered if there are there any further opinions on this one?

Absolutely no disrespect intended to Phil but I always hope/prefer to get a few viewpoints before burning my bridges and acting on advice... am hoping that the silence just means nobody else has anything different to add, but still...!

David

[Roger Mills]

What he says sounds reasonable to me. What does it say on the tin about preparation? The blurb in the URL you quoted does say that it seals the floor as well as colouring it. I put something similar (not the same make) on the floor of my (then) new garage a few years ago, and it worked a treat. Prior to painting, I got a load of dust from the concrete every time I swept it. After painting - none. And now, even though much of the colour has worn off, the concrete remains sealed, and doesn't shed dust.

[Lobster]

Thanks, reckon I'll go for it... mind you I do have a rather more serious issue to contend with first: problem is that the workshop is full of stuff, including old kitchen units that I use for storage, a full-size joiner's workbench etc - all of which needs removing, for a week I reckon to allow the paint to fully cure, and as I can't really leave it outside I have nowhere to store it all temporarily except... in the house. And that's going to go down really well with SWMBO, isn't it! Haven't let on yet, but suspect she may have guessed... watch this space. An untreated floor may yet hold appeal.

David

[NT]

You can always paint it bit by bit, in theory. We all know the practice on tha t though

NT

[Huge]

No it doesn't. There isn't a week when I don't wish I'd painted our garage floor before I filled it with crap.

[Bill]

In message , Lobster writes

Hi David, when I did mine, a few years ago, clearing the dust was the biggest problem, not matter how much I tried there always seemed a bit more to shift. In the end I used a garden leaf blower. It did a fantastic job and removed every last vestige of dust from every nook and cranny.

Afterwards the difference was amazing, no more dust and a lot easier to clean. I used 2 part epoxy paint and the only regret I have is that I didn't mix some sand in with it to roughen the surface, when wet it can be VERY slippery.

[Lobster]

So, following up my own thread just under 12 months on. I painted the workshop floor and all was great (I thought) until last weeke ned when I had cause to move a box in a corner, and found that unbeknown to me, in that area the paint has flaked off horribly - see photo here:

I'm gutted. Gutted.

The exposed white area of floor is definetely really powdery and dusty; I a ssume that's what will have caused it? I don't recall that area of the flo or being particlarly worse than anywhere else though; and elsewhere (includ ing the area which gets most hammering) paint has adhered just fine.

I did apply a 10% (IIRC)-diluted coat of paint first as per the label on th e tin.

Any suggestions as how to sort this out? I'll scrape off and make good the damaged area, but redoing the whole floor os out of the question at the mo ment.

(Whole original thread is here, FYI:

Thanks

[Tim Watts]

On Saturday 10 August 2013 20:10 Lobster wrote in uk.d-i-y:

I think you have suffered from a bit of laitence or powdery surface as you suspect.

Scrape it off, wire brush the rest of the suspect areas, apply 1:1 diluted SBR[1] to all areas (repeatedly, as it soaks in) that have exposed concrete and repaint.

[1] Much better penetration than PVA, it will sink deep (several mm easily) and will travel under the paint edges helping to stabilise those.

[Tim Watts]

On Saturday 10 August 2013 20:17 Phil L wrote in uk.d-i-y:

That's probably a better guess that wot I just said.

David: there is a DPM under the concrete isn't there?

[Lobster]

Never heard of this, but post-googling, sounds interesting, thanks.

(Yes, there's a DPM, in response to your other post)

[Tim Watts]

On Sunday 11 August 2013 00:03 Lobster wrote in uk.d-i-y:

And in response to your other post, if it is a dusty concrete, this will yield a huge improvement. Hopefully enough to fix the problem.