Granite Sills

Clarebally

Hi,

I have some bush hammered white granite sills that have some rust (builder left key) and some excess mortar around the joints, I have tried the wire brush route, however it appears to leave a black mark, any other alternatives to removing the rust and mortar,,,

tiocimarla

Clarebally wrote: »

Hi,

I have some bush hammered white granite sills that have some rust (builder left key) and some excess mortar around the joints, I have tried the wire brush route, however it appears to leave a black mark, any other alternatives to removing the rust and mortar,,,

Bolster for the mortar and maybe power hose or bleach for the stain.

Clarebally

Thanks Tiocmarla,

I tried bolster the large pieces of mortar, which worked,, the real issue was where the builder used a granite mixture for the joints instead of cement mortar, which was the correct thing to do, however, there is excess around the joint that I cant bolster as its fine, very white compared to the granite and is in the "bush hammered" indents. I thought the wire brush would be the answer, but not effective,,,

tiocimarla

Removing the rust can be done four ways to my knowledge. Lemon juice, White spirit vinegar, Apple cider vinegar and any combonation of these with salt. Dont use bleach as it will make it worse. Leave stuff on for a while and rinse. Ye might have to do this a few times and try different mixes. Its safe and wont damage the granite. As for dried bush hammered mortar Fix I would get a tiny bolster or even a nail punch and tap away carefully. But thats me and id say it would work but lets see if anyone else has a view on this:)

gsxr1

brick acid. Sanaics i think its called. Should lift it off. a disposable stiff brush ,googles and rubbergloves are needed. Its nasty stuff

I have used it many times with success in snagging houses.

dilute it first. and work from there.


hose off

Clarebally

Thanks,

Will try that stuff, can that be used for cleaning mortar off windows too (upvc)? Any idea where to get it?

tiocimarla

Ye that was the last one i forget to post oxalic acid is the man

gsxr1

Clarebally wrote: »

Thanks,

Will try that stuff, can that be used for cleaning mortar off windows too (upvc)? Any idea where to get it?

yeah it should be ok on plastic. But I would recommend that you try a small sample area
with both the granite and the PVC.

just to be safe.

Just dont let the stuff get on your skin. It will hurt. Keep water handy just in case. Even a running hose.

Any building provider will have it in 1000ml bottles

Clarebally

Thats all,

I will try them and see how I go.

antiskeptic

Clarebally wrote: »

Thanks Tiocmarla,

I tried bolster the large pieces of mortar, which worked,, the real issue was where the builder used a granite mixture for the joints instead of cement mortar, which was the correct thing to do, however, there is excess around the joint that I cant bolster as its fine, very white compared to the granite and is in the "bush hammered" indents. I thought the wire brush would be the answer, but not effective,,,

Chipping away at it like Tiocmarla says would be the way to go - unless there are large areas to be done.

I can't think of what the name of the tool is but you can hire it from some hire shops. It's basically like a power drill but rather than a chuck turning, the head consists of a cluster of steel pins (maybe 3mm in diameter) which operate in a hammer-action like fashion.

It's used primarily for knocking rust and paint off steel. It's strong enough to mark (but not dent) steel so I imagine it would be strong enough to chip away at your mortar. You could make it more effective by perhaps grinding the pins into a more pointed shape for getting into crevices - the pins tend to get hammered flat in used.

Depending on how hard you lean on it you can apply more or less hammer action. There wouldn't be much danger of hammering your cill in two but check it out for yourself