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New Granite Patio - Staining through SBR slurry within a few hours - HELP!

Posted: Sun May 17, 2020 4:58 pm
by TylerDurdenk
Hi all, hope you are well.
During this lockdown I have started trying to lay my patio. I have chosen some silver grey granite slabs and have started to lay them.
Here is my process:

6:1 sharp sand and cement mix, this has a small amout of SBR mixed into it.
An SBR and Cement slurry is spread onto the back each slab. The slab backs were wet when I did this.
I attempt to lay the slab before the SBR slurry has dried.

The issue I am having is that I appear to be suffering from reflective staining almost immediately. The slabs start to darken withing a few hours of being laid.

I have some photos here -

You can see the 3 slabs I laid yesterday, and the 2 large ones I laid this afternoon.

and here is the slurry mix being pasted on.

What can I do to stop this from happening, or is it normal to have this happen and will the issue go away on it's own?

Thanks in advance for any help.