Wire brush: correct solution or Very Bad Idea?

[swee'pea99]

One of my spring projects is to to sort out the masonry paint on the front bay window.

Googling suggests a wire brush to remove old paint, and I have one that fits in an electric drill, which sounds like an extra good idea.

But will it rip all that fancy stuff to bits?

 

[fossyant]

Be careful as those brushes can be quite aggressive

 

[sleuthey]

I used the type you have pictured around 7-8 years ago on north facing rough cast rendering and then a coat of Dulux Weathershield and it’s still going strong now

 

[presta]

My bet is that a brush like that will tear those mouldings to shreds in double quick time, try it on a small area first. When I painted my render I brushed it all over with a stiff nylon scrubbing brush, and backbreaking work it was too. The surface is really deep textured, and it's exhausting work getting right into it. I did mine with Sandtex, and it's lasted ~20 years, but the important bit is to give it a coat of Sandtex sealer first to stabilise the flakes and powdery stuff. Painting was as exhausting as the cleaning, as the only way to get the paint right into the bottom of the texture was to use a stubbing/hammering action with the brush.

The other problem with a wire brush, and power tools in general, is that they won't get into the crevices. It'll round off and wear away the convex bits whilst skipping over the concave areas.

(What if the brush tends to leave behind a steel residue ground off the bristles, are you going to end up with rust stains coming through the new paint?)

 

[Once a Wheeler]

Those brushes can be very aggressive — I've used them to bore holes in brick in the past. I think I might try a good lashing of paint stripper followed by a power hose. With a bit of luck any residue might then be removed with a hand-held wire brush. Try an inconspicuous corner first. Good luck!

 

[Randomnerd]

No to a wire brush
You could / will damage the stone.
Superheated steam at low pressure should get that off. Find a company using DOFF or TORC machines - depending on which kind of paint you have.

 

[Tail End Charlie]

Another no to anything mechanical, they would be much too aggressive. A blast with a power cleaner, then some elbow grease with a scrubbing brush or even wet and dry would be my preferred option. Then put sealer on as others have suggested before the final coat(s).

 

[Supersuperleeds]

I’d move house and let someone else have the problem.

 

[MontyVeda]

report it to the police as grafitti, then put in a claim for professional removal to your insurance company

 

[swee'pea99]

Thanks everyone - that's really helpful. Kind of confirms my instinct too, which is that the brush is far too brutal to be let loose on those mouldings, or whatever they're called. I think I'll err on the side of caution, and use a stiff brush to remove anything flakey, then simply paint over. It's a bit slack of me, but I don't think I have the energy to do the whole thing thoroughly. It's the sills that need it the most, and them I am happy to let loose with the wire brush. Thanks again.