How to remove grouting marks on sandstone - Grout staining on sandstone

[Penlop]

I had some London stone 'harvest' slabs laid on our patio and the builder insisted he could use the easipoint grouting I had bought the day after laying them. He didn't use a mortar gun and I'm left with white marks from the grout round the edge of each slab (50sqm) which has destroyed their appearance.

I read lots of your advice and previous discussions so didn't use an acid cleaner but have tried scrubbing (much to the amusement of neighbours) and Lithofin power clean with no effect. Sand blasting isn't really an option now as we have a glass balustrade round it.
The builders have left me to it saying it will wear away with time but I can't see that happening. I don't want to seal in the problem but I did stupidly use lithofin's colour impregnator thinking that might disguise the white marks -ha!

I know you've had this question so many times but I still can't find the answer -Any suggestions would be so welcome..

[PB] ???

[lutonlagerlout]

have you got a photo penny?
it may just be efflorescence
I did some harvest a little while ago and pointed them carefully with the gun
there has been some picture framing effect due to the high strength of the pointing mortar
of course if it is mortar staining then he is talking utter bollocks
cheers LLL

[London Stone Paving]

PB

1. The builder should have used a gun
2. Have you sealed the whole patio, or just a test area?
3. It will come off with acid, guaranteed. I have had the same issue with limestone which is much harder to clean and I have completely removed the marks.
4. Your builder is completely out of order. He should be sorting this out not you.
5. Email me some pictures and I will post them on this site and also get back to you with a fix

steven@londonstone.com

[London Stone Paving]

have you got a photo penny?
it may just be efflorescence
I did some harvest a little while ago and pointed them carefully with the gun
there has been some picture framing effect due to the high strength of the pointing mortar
of course if it is mortar staining then he is talking utter bollocks
cheers LLL

He has installed it with a trowel and then not wiped off properly, I would say

[Penlop]

I don't think its efflorescence- its definite white staining round the edge of each slab. Unfortunately its raining today so photos aren't an option yet but as soon as we get a dry period I will email some. It doesn't look so bad when its wet!

Yes we did use the colour enhancer over the whole patio! would I need to try and remove that first?
Wouldn't an acid cleaner ruin the colour of the stone?
The builder is definitely not interested.

Thanks again for any advice

[London Stone Paving]

I have succesfully used acid on sandstone before. You do need to take precautions though and i would not advise that you do it without taking professional advice. There are also other products you can use which are non acid based.

We had exactly the same problem on our display. In our case the landscapers did use a gun, but they failed to wipe off the excess. I can understand your frustation but dont worry, its an easy fix.

Disssapointing that builder has washed his hands of it. Look forward to the photos

[lutonlagerlout]

with hydrochloric acid you need to pre wet the stone and be very very careful regards health and safety
r and a pressure washing
is probably the UKs leading expert on this kind of thing
I would be tempted to ask his advice and maybe a price to do it
LLL

[Penlop]

Its difficult to get professional advice down in deepest south Devon. I have emailed steven at London stone with some photos ( I can't seem to upload them myself) but no response yet.
I wonder if I try the weiss cement stain remover or the weiss Z.IMP if that would work without dmaging the stone?

I'm also going to have to be very careful as around the edge we have a rubber seal holding in the glass balustrade!

thanks for all the advice so far

[London Stone Paving]

Hi Penelope
I have not received any photos yet. Can you try sending them again?
Please do not do anything further until we have had time to look at the photos. As I said before I think there should be an easy fix and waiting a few more days will not make any difference
Steve
P.s I got your second email but not first

[Penlop]

Hi Steve

Apologies - the photos should be with you now- look forward to the easy fix solution.

Penny

[London Stone Paving]

Here are the photos. Nice view by the way









There is a little bit of effo but its mainly grout residue. 5 things are required to fix this

1. Lithofin builders clean
2. A stiff deck brush
3. A jet wash
4. Elbow grease (lots of it)
5. Lithofin Bero

The lithofin builders clean is acid based so make sure you wear gloves and eye protection when using it. The fact that you have sealed it will not make a difference as the sealant operates below the surface of the stone and this residue will be sitting on the surface of the stone. However you will need to re-seal after you have removed the grout residue

Whoever is doing the job for you needs to follow these steps.

1. Pick a small area out of the way to do a test patch

2. Wet the area first (this will prevent the acid from damaging the stone when you apply it)

3. Mix equal quantities of the bero and builders clean together (beware as both are acid based, so eye protection is a must and beware of the fumes as well)

4. Pour some of the solution onto the affected area and scrub vigorously with the deck brush for 5 minutes or so

5. Leave the area for 15 minutes and then thoroughly jet wash the affected areas, keeping the jetwash nozzle close to the stone (this is not reccomended normally as if its done repeatedly it can wear the surface of the stone)

6. This should shift it all. If some grout residue still remains then carry out the process again

I should perhaphs re-phrase my statement that its an easy fix. It will take a bit of effort but a lot less effort than re-laying the stone which sometimes can be a consequenence if the problem is severe enough. If its not a job you fancy doing yourself I can reccomend someone but he would have to travel down to you from Croydon so there woud be a cost to it. On the plus side he would get the job done quickly and with no fuss as he would come armed with all materials and tools required.

Hope thats helpful. If you need any further advice give me a shout

Steve

[Penlop]

Thanks for that Steve

I will attempt it myself with a lot of elbow grease and protection! Just checking though, do you recommend using the 50/50 solution undiluted?

Penny

[rimexboy]

Wow that is some view

[lutonlagerlout]

I have shot people for less than that
the installation of the flags looks good but the pointing is 100% pish take
shame on you, whoever pointed that
LLL

[London Stone Paving]

Thanks for that Steve

I will attempt it myself with a lot of elbow grease and protection! Just checking though, do you recommend using the 50/50 solution undiluted?

Penny

Hi Penny

Yes the 50/50 solution should be un-diluted. But make sure you soak the area with water first.

Any advice or further information, you can always contact me

Steve