Hi all - First time post, coming here for a bit of advice.
I'm having my garden landscaped by a local company, and as part of that have had sandstone slabs laid.
There have been lots of delays due to weather and other bits, what was originally going to be done over a couple of weeks has taken a couple of months.
The owner of the company i'm using seems to be a nice bloke, but I've got some concerns with the slabs. Originally he had another company coming in to lay the slabs, but they cancelled last minute so he got someone else in. When laying the slabs I noticed a lot of the mortar going on the slabs.
I've been away on holiday and they did the pointing (looks to be with sand and cement), and more mortar has got on the slabs and not been cleaned off. This has obviously now dried very hard.
The guy is currently away on holiday, so I wanted to give the slabs a rinse off to get rid of the dust and see what they look like, and when wet the scale of the mortar staining really becomes apparent. When dry it looks grey and hazy around the edge, not great but less visible. When wet it really is obvious.
I tried the pressure washer, doesn't make any difference at all.
I have some brick acid (Sika 10% stuff), so done a few test pieces from off cuts, and it did not damage the stone, so tried that. I'm aware that brick acid could cause staining hence the test and only trying it on 1 slab. First of all 50/50 which didn't seem to do much, then applied neat with a paintbrush onto a damp slab. The mortar fizzed, I left it for 20 mins (kept checking and didn't let it dry) and then used a very stiff nylon brush. Made a small difference after about 5 minutes of scrubbing. To get the slab cleaned up with this method would probably take me 4 or 5 repetitions and quite a lot of time.
Personally I can't see a way of getting this up with any sort of ease, but I'm *hoping* there is a way of doing it. I'm not going to bring it up to the guy whilst he is on holiday but hoping you can push me in the right direction of how I should approach it when he's back to finish up. Am I worrying about nothing, is this standard procedure and they will get it cleaned off no bother? Or is it a serious issue and I need to bring it up as early as possible?
I've attached a few pictures of both wet (after pressure washing) and as they were drying out.