The Brew Cabin

Posted: **Mon Nov 23, 2015 8:22 pm**

Hi,

Been having a bit of a nightmare recently with the weather, finally got a dry day and went in hard doing as much pointing of some sandstone paving as i could. Unfortunately now it's dried i can see in my haste i managed to smear some cement from the joints on the edges of the flags. I'm pretty sure i did this by brushing off any excess mortar a little too soon while it was still a bit wet.

i'm finding this pretty distressing as i'm a bit of a stickler for this type of thing and where i'm usually pretty clean but i made a bad judgment call during my elation over it stopped raining, got a bit sloppy.

What's the best way of removing a smeared cement stain do you reckon? a wire brush seems like it would damage the slab as it's not like its a clump of dried mortar and i'm not going near any brick acid due to it being sandstone. just seems like it's one with the slab. any ideas??

Posted: **Mon Nov 23, 2015 8:32 pm**

Phosphoric acid substitute
Bought from here
http://www.tilinglogistics.co.uk/Tile-pr....c-spray

Posted: **Mon Nov 23, 2015 9:46 pm**

Cheers for reply.Being acid based will this not be risky with sandstone?? especially indian sandstone.

Posted: **Tue Nov 24, 2015 6:43 am**

brick acid is fine with most indian sandstones
its lime stone you have to watch out for
of course you need to check it on an offcut first

always pre wet stone before you use acid
LLL

Posted: **Tue Nov 24, 2015 7:37 am**

ok cheers.

i've seen some discolouring of indian sandstone from previous experience using brick acid, nothing major but similar to whats described in the staining page on this site. Also after reading more about the product described above it doesn't mention sandstone as an approved material to use it on...... so i remain slightly uneasy haha. i'll just make sure to test it on a few off cuts first!

thanks for the advice.

Posted: **Tue Nov 24, 2015 7:37 am**

smobb wrote:Cheers for reply.Being acid based will this not be risky with sandstone?? especially indian sandstone.

It will be fine, if not I wouldn't have recommended it.
Follow the instructions to the letter that is on the packaging and I'd use a stiff nylon brush as these are fairly chemical proof.

Acids to be avoided is Hydrochloric acid aka brick acid one reason is it comes in different strengths and to many people don't read the labelling so this is when accidents happen.
But do a test area or piece if you can, pre-wet the stone mix the phosphoric down to suggested mix as per the instructions and dwell time. Depending on the staining you might need to have a couple of attempts.

Posted: **Tue Nov 24, 2015 7:39 am**

smobb wrote:ok cheers.

i've seen some discolouring of indian sandstone from previous experience using brick acid, nothing major but similar to whats described in the staining page on this site. Also after reading more about the product described above it doesn't mention sandstone as an approved material to use it on...... so i remain slightly uneasy haha. i'll just make sure to test it on a few off cuts first!

thanks for the advice.

It's fine on Sandstone if you follow in the instructions, I use this on Limestone as well when needed.

Posted: **Tue Nov 24, 2015 4:07 pm**

ok cheers mate, thanks for the info, i'll give it a go.

The Brew Cabin

Rushed pointing - Smeared cement stains