Giant sandstone fireplace

[Rayray]

Hi everyone, found this forum to be quite the wormhole, and very useful... but as I haven’t found anything on here or else where on the web about my current conundrum I thought I better post a post...

We bought our sandstone built Victorian terrace house about 7 months ago and have since found it’s riddled with damp corners. One of the things we are doing to combat the damp (and rising gas prices) is install a log burner in the giant fireplace we found in our back room which we use as the lounge.

And I mean giant, the stone lintel (which I haven’t actually taken a photo of, so this is to follow) is a good foot tall and at least half a foot deep... but it needs some work to return it to its former glory...

Can anyone help with how to clean up dirty sandstone? It seems to have some black paint on it, which I’m hoping to remove...

Any advice greatly appreciated

 

[a twig]

Some maniac had done a similar thing on a bath stone fireplace in our house.

Initially I used a 3” wide masons chisel and dummy to do most of it and then at the last (with very light pressure, good respirator and all the windows open) an angle grinder with a selection of stone polishing pads to re-dress the stone into something acceptable.

Non powered rasps etc could be used for the last bit - take longer but less mess

 

[BlueTed]

Paint stripper should work. If the stripper is covered in cling film for a few hours and then scrub off with soapy water and a medium to stiff brush this should do the trick. If there’s any paint left just repeat the process. This will also clean the stone and you should get a nice finish but without damaging the surface of the stone.

 

[Feltwell]

If you google "Strippers of Sudbury", they do just about the most comprehensive range of paint strippers anywhere, and do test packs. I'd start with KlingStrip.

 

[Rayray]

Thank you everyone, I’m reluctant on the paint stripper front as I’ve read this can damage sandstone due to its porosity... also, it doesn’t look like your normal black masonry paint, is there any particular thing cowboys use to cover stone before plastering over it?

 

[Rayray]

Some more photos

 

[Feltwell]

Thank you everyone, I’m reluctant on the paint stripper front as I’ve read this can damage sandstone due to its porosity... also, it doesn’t look like your normal black masonry paint, is there any particular thing cowboys use to cover stone before plastering over it?

By coincidence.......

I bought a sandstone window cill off Ebay a while ago, it's been sat outside the back of my house on trestles ever since, too damn heavy to move! I'd been looking for a nicely weathered one of the right size and profile for ages, to match the existing ones on the house. I didn't want a new one.

It's caked in a mix of masonry and gloss paint by the look of it. I had the old remnants of a tub of klingstrip in the garage, although it was a bit dried out I figured I'd give it a go in a couple of places on the underside edge. That was on Sunday - I've just taken it off after 48 hours.

It's worked a treat - paint all clean out of the pores of the stone, and this was cleaning it off with warm water and a scrubbing brush rather than a pressure washer. As it's a paste I don't think it soaks into the stone like a liquid stripper like Nitromors could. The stone looks fine.

I'd say it's well worth your while giving it a go, it's by far the most gentle method of paint removal. Put it on good and thick, wrap in cling film with the edges gaffer taped to the surrounding plaster, and give it the full 48 hours before removing it. Of course I'd start with a test patch in a bottom corner.

I'm just off to buy more to finish the job now.

It's possible that your stone has been tarred, but I'd imagine it's some sort of paint. If Kling strip doesn't touch it then it's worth giving Strippers of Sudbury a call. I had old paint splashes to remove from brickwork, klingstrip dealt with most but one particular sort it wasn't working too well on, the alternative they suggested was much better.

 

[a twig]

As per my previous - our finish looked almost identical to yours, in our case it was black jack (bitumen containing paint) to “seal the stone” before another finish was put on top.

Mechanical methods were the only thing to shift it but do tread lightly as sandstone and limestone can disappear very quickly under a heavy handed power tool.

Using a “vanity disc” in the angle grinder works well

 

[Feltwell]

As per my previous - our finish looked almost identical to yours, in our case it was black jack (bitumen containing paint) to “seal the stone” before another finish was put on top.

Mechanical methods were the only thing to shift it but do tread lightly as sandstone and limestone can disappear very quickly under a heavy handed power tool.

Using a “vanity disc” in the angle grinder works well

Does that not mean you end up with smooth finished stone though, rather than the textured finish the picture above shows?

I had the sandstone lintels above my porch refinished with a disc, they look great but it's a smooth machined surface (in this case as it would have been originally).

I just checked the substrate and coating check tool on the Strippers website (careful to choose the right website ), they reckon their Solvistrip product works for bitumastic coatings on stone. I've used that on brickwork to remove tar stains from messy flat roofers, staining had been there for at least 30 years, it took it off no problem. It was a smoother faced brick mind, nowhere near as rough as textured sandstone.

 

[malcolm]

You can buy samples of the paint strippers to try on a small area. If it is bitumen then dry ice blasting might be effective if done carefully.

 

[a twig]

Does that not mean you end up with smooth finished stone though, rather than the textured finish the picture above shows?

Definitely - to my eye peering at the picture that “textured finished” at the front with the black paint is damage rather than a particular aesthetic? So personally I would want those taken back to a flat surface. Doesn’t have to be a machine, stone masons chisels, drags and perseverance can get you there.

The sides look like they are rough finished and intended to be plastered over in my unqualified opinion. I haven’t seen many Victorian fireplaces with intentional exposed finishes like that

 

[Rayray]

in our case it was black jack (bitumen containing paint) to “seal the stone” before another finish was put on top.

I feel like this might be my case too... because it also stinks of tar when you start trying to wash it or brush it...
How smooth a finish did you end up with? I’m not adverse to polishing it up nice and good tbh.

Also, yes the sides are definitely rough finish, but the plaster that was covering it was so damp it just lifted off with a putty knife, so I’ve got to decide what I’m going to do there, either smooth it off or plaster it up...

 

[BlueTed]

I feel like this might be my case too... because it also stinks of tar when you start trying to wash it or brush it...
How smooth a finish did you end up with? I’m not adverse to polishing it up nice and good tbh.

Also, yes the sides are definitely rough finish, but the plaster that was covering it was so damp it just lifted off with a putty knife, so I’ve got to decide what I’m going to do there, either smooth it off or plaster it up...

it sounds very much like there’s an underlying damp issue if the plaster was damp and peeled off and bitumen was used in the past. Perhaps the fireplace itself is blocked with rubbish, and removing this should resolve an damp. I have two inglenooks that were built over with 3/4 different fireplaces and they were incredibly damp. It was hard work clearing them out but it seems to have resolved the damp on these areas entirely.

 

[BlueTed]

Does that not mean you end up with smooth finished stone though, rather than the textured finish the picture above shows?

I had the sandstone lintels above my porch refinished with a disc, they look great but it's a smooth machined surface (in this case as it would have been originally).

I just checked the substrate and coating check tool on the Strippers website (careful to choose the right website ), they reckon their Solvistrip product works for bitumastic coatings on stone. I've used that on brickwork to remove tar stains from messy flat roofers, staining had been there for at least 30 years, it took it off no problem. It was a smoother faced brick mind, nowhere near as rough as textured sandstone.

Excellent recommendation, I had not come across Strippers before, just ordered a sample pack to try on an area of brick. Sorry to highjack this post with my comment!

 

[Feltwell]

Definitely - to my eye peering at the picture that “textured finished” at the front with the black paint is damage rather than a particular aesthetic? So personally I would want those taken back to a flat surface. Doesn’t have to be a machine, stone masons chisels, drags and perseverance can get you there.

The sides look like they are rough finished and intended to be plastered over in my unqualified opinion. I haven’t seen many Victorian fireplaces with intentional exposed finishes like that

It's hard to say isn't it? The front is a hand tooled finish, it could have been meant to be like that or it could be someone attacked it to give a key to plaster to! It looks a bit well done to have just been for a key though, I have seen fireplaces with finishes like that. The sides are definitely rougher.

Damp - I agree with the comments above, if the chimney is blocked or if the external stack/roof/leadwork was in a bad condition it could have been letting water in. Given a choice between getting up on the roof and fixing the problem properly, or reaching for the paintbrush to put some magic gunk on to hide the problem inside, alas many will reach for the paintbrush.

Dry ice blasting as Malcom suggested is an interesting one, if you wanted to keep the current finish and a chemical didn't work. I would have thought dry ice would work well on bitumen, though at a price of course. If you want smooth though then you may as well grind it off. The question mark to me is always how much you have to grind off to get the finish you want - my sandstone lintels were left with the worst pits in, that looks OK outside (just makes them look old) but maybe not so good in a fireplace.

 

[Sam W]

Always fun digging out buried treasure. A couple of comments from me.

1. We've got a couple of similar surrounds on our house and I think they always were black. Couple of pictures attached, one is a surround that was in place when we bought the house, paint is as we received it. The second is a surround which we've recently retrieved from the garden where it must have been say for many years, but note the remains of black paint on that one too. I've been told black was chosen as it helps the stone emit heat collected from the fire TLDR repainting your fireplace fully in black may just restore it to how it was historically.

2. The stone specialists who reinstalled/rescued the surround from the garden recommended Peelaway as a paint stripper in these situations

3. If it is bitumen on your surround, I found solvent based tar remover for cleaning cars very effective for getting bitumen off our quarry tiles. Note of caution - I think it's very likely some of the solvent would soak into the sandstone, so definitely do a trial in an unobtrusive area and see what happens before sloshing it over the whole surround.

 

[Athers1971]

I feel like this might be my case too... because it also stinks of tar when you start trying to wash it or brush it...
How smooth a finish did you end up with? I’m not adverse to polishing it up nice and good tbh.

Also, yes the sides are definitely rough finish, but the plaster that was covering it was so damp it just lifted off with a putty knife, so I’ve got to decide what I’m going to do there, either smooth it off or plaster it up...

Ooh, just wondering how you went on with your fire surround and removing the black paint? What worked in the end in terms of stripper and what did the end result look like? Do you have before/after pics you can share? I have a similar situation....