Sbr primer concept

[Left handed]

I'm going to be laying a Indian sandstone patio in the near future and have read there can be adhesion problems. Main section of website suggests using a SBR primer.

Will this allow me to use a drier bedding mix and hopefully keep flagstones clean. I've laid flagstones in the past and used quite a wet mix to make laying easier but found the wet mix sometimes squeezed up through joint and would leave nasty stain.

SANDSTONE ADHESION PROBLEMS - when does it happen? Do the flagstones not stick from day 1 or do they come loose in the months or years ahead?

BEDDIG MIX SLUMP - I've been scanning forums and quite a few tradesmen recommend a wetter mix, saying flagstones go down easier and stick better but I'm worried wetter = messier!!

My concerns are laying a patio covered in stains or the flagstones having to be relaid.

How much SBR would I likely use on approx 30m2 patio?

ANY ADVICE OR INFO MOST WELCOME.

[lemoncurd1702]

I find a wet mix better myself. Just wash paving with a soft brush dipped in water every couple of slabs.
Sbr definitely with a dry mix and preferably with a wet mix also. 5L of sbr is the smallest your likely to find and will leave you a amount to spare.
Mix it with cement powder to a creamy consistency and slap on bottom of slabs. You don't need to cover every inch, in fact I normally stay well clear of the edges where your fingers will become covered in the sbr mix.

[Left handed]

LC thanks for taking time to reply.

Would you consider SBR primer on a domestic garden project necessary or more likely needed on commercial projects?

When you plan your works is it your standard practice to use a SBR primer on I/sandstone?

Also, at what point do (lack of) adhesion problems occur? A day after or months/ years down the line.

Thanks

[lemoncurd1702]

I just use sbr regardless now. As I say you don't need to cover every square inch, even if a third is covered that slab will never move if bedded properly. It doesn't set that quick that you can't adjust or relay if not quite right.

[lutonlagerlout]

I know its not as written but we add around 100ml of SBR to all paving mixes now,i found the slurry painting to messy
to date no issues,but use a 5:1 mix grit sand:cement with approx 10-12 litres of water and 100ml of SBR,wet though
cheers LLL

[exoticpete]

we prime everything now including setts with larsen or instarmac you get used to it after a while and it makes the paving bullet proof

[lemoncurd1702]

we prime everything now including setts with larsen or instarmac you get used to it after a while and it makes the paving bullet proof

Agreed Instarmac is brilliant.
No merchants seem to stock it or similar this down my though.
Must remember to order some with next Marshalls direct to site.

What Larsen product is similar to instarmac Pete?

[Left handed]

Hi Luton lager lout

When you say you add "100ml SBR to the mix", do you still add a plasticiser too?

I guess a wet mix + SBR when done poorly has a high stain risk? and that stains there for a long time?

[Left handed]

LC & LLL you both say you prefer a wet mix, how would you compare it to a bricklaying mix? A similar consistency?

[lemoncurd1702]

Pretty much. Maybe not quite as wet but add plasticiser to make it flexible. You'll just have to experiment with the mixes.

[exoticpete]

Hi Lemoncurd this stuff http://www.londonstone.co.uk/paving-....-primer

[Left handed]

Is the Larsen gear basically a premixed SBR/cement primer?

How does it compare for ease of application and cleanliness?

Do you mix with water and paint it on?

[exoticpete]

Not sure what its made of cement based, mix with water to creamy mixture and paint on clean up any splashes straight away, I find its better than DIY sbr cement mix tends to not go off as quick

[lutonlagerlout]

I prefer a bit wetter than bricklaying mortar
but I am careful and any splashes are washed off straightaway with clean water and a soft brush
I have a technique for wet mix with the furrows and it has served me well so far
LLL

[lemoncurd1702]

Hi Lemoncurd this stuff http://www.londonstone.co.uk/paving-....-primer

Cheers Pete. Managed to find it at a local merchant that I forgot existed