Stripping paint off window sills ( concrete)

[aprilsweetheartrose.]

I need to sort out the exterior of my house. The window sills are all concrete. They have been painted possibly three or four times. I last had them done several years ago and now the paint ( was gloss) is flaking. In some places it is going back to the original concrete. I thought it might be nice to get rid of the pain and just have the original concrete sills but brushing and scrubbing seems to have come to a dead end. Can anyone tell me how to get rid of the coats of pain and go back to the concrete ( it would be nice if there was a product for this ).

[Animal]

methylene chloride, for outdoor use only. Heatgun also works So does a blowtorch, but they're a hazard All 3 make a mess.

[alan_m]

In a similar situation with too many layers of flaking paint on sandstone (with a hard surface) I found the only effective method was a blowtorch and scraper and then sanding down the remnants of the carbonised paint. This does not leave a perfect uniform surface but I already had to make (cosmetic) repairs and I was going to re-paint from the outset.

I wasn't too concerned about the existing wooden window frames as this bit of renovation was in preparation to getting UPVC double glazing installed.

The bottom layers of paint had been applied probably 50 years before and I guess had lead.

I first tested with a paint stripper from one of the sheds - one where you layer it on and then cover with cling film and leave it for a day. I found it to be somewhat useless at stripping more than a couple of layers of paint per application and considering how much I would need to complete the job I'd be poorer by £100s

[aprilsweetheartrose.]

Thank you all for the replies. I will have to find a heat gun ( I am not sure I could manage a blow torch) . Some of the paint on my window sills must also be around fifty years old. Its needs to go back to the concrete base as paint on paint isnt working now.

[SH]

grit blasting or shot blasting but this will require the hire of a shot/grit blasting gun and supplies of corundum grit.

Great for stripping paint off stone or off wood beams that had been painted black.

Messy though as you have to clean up the ground.

S.

[The Natural Philosopher]

Some pressure washers will do the job with just water. A wire brush on a drill or angle grinder is quite effective in some cases, but try it out first.

[SH]

yes jet washing worked for me to strip the old & dark fence stain off wood before painting it a light colour :-)

[Andy Burns]

Or you can get a sand-blasting adapter that will suck up from a bag of kiln dried sand (it must be bone dry or it'll clog) e.g

[Andrew]

A better way is blasting the timber with solid CO2 pellets -

This apparently does less damage to the surface of the wood.

There was a Grand Designs conversion of a warehouse (?Hove) not too long ago where this method was used. Not cheap.

She could always try using a Karcher and see if power jetting gets any paint off.

[Jonathan]

Metal sanding disc

Jonathan

[Vir Campestris]

Some ***** in the past painted a lot of the internal beams in our house black. There's a little item in the back of my mind that we ought to get them stripped.

AIUI the great advantage of dry ice blasting is that you don't have to sweep it up later - it just vanished all on its own.

Nobody seems to mention sweeping up the paint dust. Though I'm sure that's not such a big problem as loads of sand.

My son's house has window cills of either concrete or some sort of stone, and I have the same problem; I've cleaned them as best as I can but there's no way I'll get it good enough to be bare. On my list is putting some new paint on them.

Andy

[The Natural Philosopher]

The loads of sand get *everywhere*

You want to hermetically seal any room with sheets of polythene and tape and vacuum thoroughly after doing any grit blasting.

[SH]

If you do dry ice blasting indoors, you will need to have a oxygen bottle and face breathing mask or you will be asphyixiated....

[Vir Campestris]

I am extremely unlikely to do any dry ice blasting of any type. I might possibly hire someone... And yes, I know, this is uk.d-i-y...

Andy