Floor paint over PVA

[Steve Walker]

I primed our new garage floor with pva to keep the dust down, and then a while later painted it with solvent-based Leyland floor paint off Screwfix.

Surprise, surprise - the solvent-based paint doesn't adhere well to the concrete, and tends to flake off under heavy use. Getting fed-up of having to repair patches. So I want to scrape it all off (nice job), give the floor a good wire-brushing and repaint. Some kind of epoxy coating seems best...

This is where I need the hivemind, please. Options are to use a water-based floor paint that might adhere to pva-primed concrete, or some kind of intermediate undercoat which will take a solvent final layer.

Any ideas please?

Steve

[The Natural Philosopher]

not using PVA would have been the answer. PVA is also a release agent for epoxy, so that wont stick, either.

[Alexander Lamaison]

I think the solvent vs water choice is beside the point. I suspect the problem was that you primed it with too much PVA leaving an ice rink for the paint to adhere to. Neither solvent-based nor water-based paints will stick to that properly.

But, the solution would be exactly what you suggest: abrade the floor (angle grinder?). Then either reprime with a *dilute* PVA solution or just stick some new paint on (solvent or water based).

What do others think?

Alex

[Phil L]

It's a waste of time getting the pva off only to apply more, this is the problem - pva shouldn't have been used at all.

To the OP: get it down to bare concrete again whichever way you can, and re-paint, BTW an angle grinder isn't suitable.

The paint you used first time is suitable, just not over pva.

[The Natural Philosopher]

Only hope is to use a cement based leveling compound - that will stick.

[Alexander Lamaison]

Agreed.

I'm curious why? Would a quick wizz with a stone grinding disk or wire brush cup not do the job?

Alex

[Tim Watts]

On Saturday 09 February 2013 17:39 Phil L wrote in uk.d-i-y:

I agree.

PVA is rather over enthuastically used in areas that are not suitable - and damp garage floors count.

Wire brush (powered would be quick) should knock it back to leave some exposed aggregate and sand particles.

Once you have that, epoxy should have a chance :)

On the plus side, it was PVA and not bitumen (which is a prize bastard!)

[Phil L]

A wire brush attachment might be ok but an angle grinder wouldn't - there's not enough of the disk in contact with the floor at any one time - you can hire a concrete plane which has carborundum blocks in a spinning plate and it's pushed up and down like a lawnmower, these things are horrible to use, dust everywhere, the blocks keep falling out and the noise sounds like a harrier taking off, they are meant for taking a few mm off uneven floors, but they aren't very good at it, probably ok for removing paint though

[Tim Watts]

On Saturday 09 February 2013 18:02 Phil L wrote in uk.d-i-y:

There's a variant tool that *good* hire shops have, - not sure of the name - but is built like a cylinder mower with hard tipped flails mounted on pivots on the cylinder. These spin with the cylinder and thwack the floor with their hardened points.

Yes - it produces dust like a bastard. It will eat 1cm out of very weak screed in about 10 seconds, but on hard decent screed it will at worst put slight grooves in the surface. It will remove all soft material and a little of the surface.

I offer it only as a suggestion. I wonder if there is something similar but a bit more subtle?

[Bill]

In message , Steve Walker writes

What ever method you use to remove what is there now, good luck, enjoy :-)

But once you are back down to clean concrete I would use a 2 part epoxy paint. A lot of work to get the area dust free and clean to start with and smelly and messy when applying it, but a really good hard wearing surface when it is done. You will never need to do it again. If it is only being used as a domestic garage it will probably outlive your occupation of the place.

[Steve Walker]

Thanks Bill, and all other contributors. The two-pack epoxy stuff looks excellent, and the finish you describe is what I'm after.

[Bill]

In message , Steve Walker writes

It is very good, I did my garage/workshop a few years ago and I'm very pleased with the result. The only word of caution would be, if it is likely to get wet, to look into adding some coarse sand to the mix to give added grip to the finished surface.

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[stuart noble]

AS NP says, floor screed sticks like the proverbial, mainly due to the SBR content. Used instead of pva, I don't think the flaking would have occurred