Using a cement dye when grouting sandstone slabs - advice?

[b3taman]

Hello folks
Have almost finished laying quite a large patio (30m2) using 22mm Strata sandstone grey slabs. I'm thinking a darker cement for grouting will look better than plain cement. If I use a cement dye I assume the cement could then stain the slab edges very easily if any of the mix gets on them?
Any advice about the best method to use to avoid this will be welcome. Despite reading as much as I could on this forum and on Paving Expert beforehand the patio has been an absolute bugger to lay and I really don't want to ruin it at this late stage!
Thanks.

 

[kbdiy]

I'm guessing you will have some offcuts from the slabs so you could try a test piece to see if staining is likely to be a problem. Keeping the slabs and mix as dry as possible would be my best guess to avoiding the issue but testing would prove that for you.

 

[r896neo]

Don't do it. cement dyes do not last in paving pointing. IT will be normal grey within a year.
If you really want a darker joint use a premixed mortar product like parex easipoint or larsen GPM. Or you could make your life easy and use a 2 part resin mortar like gtfk or rompox D1. Or marshalls weatherpoint 365 which is a one part polymeric.

Have a google of those products or check out paving experts pointing flags page.

 

[b3taman]

Thanks for your advice guys.
r896neo, are these premixes or resins easier to apply? I would have hoped to find a product that could be applied in a similar way to a mastic gun would make life a bit easier.
I have read the paving expert page but he cautions against the cost of these products. But if it's easy to apply and there's reduced risk of staining the slab edges then I would be very tempted..........

 

[r896neo]

the premixed mortars are applied with a mortar gun like a big caulking gun.

The resins or polymerics are super easy to apply and because there is no cement there is zero risk of staining. They can also be applied in damp weather. They are more expensive though.

check out the mftrs site for videos of how to apply.

http://www.marshalls.co.uk/homeowners/view-weatherpoint-365-brush-in-patio-jointing

The resins like gtfk nexus or rompox d1 are applied the same but need mixed with a catylst/ hardener.