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Topic: Silver granite patio seal and joint?< Next Oldest | Next Newest >
alrat
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Posted: 23 Mar. 2019,18:39 QUOTE

Hi Folks,

Really appreciate all the advice here from experts and DIYers on here. Through reading this site and forum posts, I've successfully laid 32 m2 of 900x600x25mm flamed silver (sesame) granite slabs in my shaded back patio. I've followed all the rules so far, minimum 75mm sub base, 30mm full mortar bed, albeit 5:1, not recommended 6:1, but it still seems permeable. Slurry render on the back of the flags before laying and it's looking good so far.

But now I don't want to mess it all up doing the sealing and jointing wrong and would really appreciate your advice. I laid it in October, almost 6 months ago and left it to release effervescence, but there's been none.  I'm planning for spring/summer seal and joint.  I want to use a basalt colour for jointing, but I'm terrified about messing it up with picture framing and can't bare to use a sweep in jointing compound that might stick in  the rough surface of the slabs even if sealed, so was thinking....

1) An impregnating sealer first (Adseal HD Sealant or Lithofin MN StainStop Plus?). Want to guard against grout picture framing/staining, but also red leaf and red berry staining. Invisible sealer as I don't want the slab colour to change.

2) A polymeric jointing compound, but piped in using a gun, still using lots of water? Joints are 10mm wide and 20 to 30mm deep.  I'm not worried how long it takes, just want a neat job with least chance of staining.  Which product? I don't think I could work fast enough for a 2 part product, unless I swept in, eek.

I'd really appreciate anyone's thoughts on this, as I understand with silver granite it's vital to get jointing and sealing products that are compatible with the stone.

Thanks & Regards,
Al.
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lutonlagerlout
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Posted: 24 Mar. 2019,14:00 QUOTE

is this the chinese G603 granite?
it is very very porous and sealing will cost you a bit
I know it sounds off as most people think of granite as hard but these are very very porous
We have had good results with Lithofin MN stainstop in the past but you will still get stains if its shady
the last lot of this we laid we used grey vdw 815  and it went ok
not sure of black on grey joiting?
cheers LLL


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alrat
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Posted: 25 Mar. 2019,12:12 QUOTE

Thanks LLL, it's good to hear from someone with experience of these slabs.  Mine are definitely from China and silver/sesame granite, so I suspect they must be G603, but from a local supplier.  They seem pretty good quality as far as I can tell 25m thick, which makes a difference, but damn heavy!  If it's heavy rain, water does tend to sit at the corners if there's a slab with a raised edge and they dry out really quick after rain, so hopefully they might not be as porous as some.

Sounds like it's going to cost a bit to seal though, only concern with Lithofin MN Stainstop, is from the sealant trials on here, it looks like there's a slight wet look applied to light stone?  I'd love to keep them dry look, but most importantly it's good to hear you've had good results with the Lithofin.  I might try my own trial with Adseal HD and Lithofin MN SS.

My reason for planning dark joints on light grey slabs, is that at the moment with no joints it just looks like dark shadow and looks really good on the uniform pattern large format slabs.  The jury is out.  Can you confirm if you sealed before jointing with the vdw 815?   I suspect  this is a necessity.

Thanks again,
Al.
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lutonlagerlout
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Posted: 25 Mar. 2019,18:27 QUOTE

we bought them presealed from London stone so no dramas,but better to seal first yes
LLL


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Tony McC
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Posted: 30 Mar. 2019,11:04 QUOTE

If you want an 'invisible' sealant, then DryTreat is probably the best option. It's seriously good stuff, if a little pricey.

As for the jointing, I no longer recommend any one-part polymerics, even the good-ish ones. I can't bring myself to put forward a product I know to be inferior.

If you pre-seal, and allow at least 3 days to cure, a good quality 2-part resin mortar applied as a slurry (gun injection is back-breaking and not a job for a DIYer) will wash off without a bother and the sealant will prevent most, if not all, picture framing.

The key to success is to use plenty of water, both before applying the slurry, while brushing/squeegeeing it in, and after to wash off. There is no such thing as too much water with these products.


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alrat
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Posted: 30 Mar. 2019,15:03 QUOTE

Tony thanks for your post and expert advice, between you and LLL I know I'll be sealing first and then using a 2 part resin mortar for jointing.  I'll be using lots of water during application.

Still not sure on the sealer, think I'll need to do my own trial.  Looked at drytreat before and yes it's costly but I like the 15 year potential, but it came out very badly on the sealant trials on this website.

Maybe I need to do my own test.  I'll need to see how this does and Lithofin MN whether it does change the surface to too much of a wet look, as it appears to have offered better results in the trials.
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Tony McC
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Posted: 31 Mar. 2019,10:06 QUOTE

I was more than a bit surprised at the results of the sealant trials. DryTreat and one other well-known name fared far worse than I had expected while a couple of products I wouldn't normally rate did surprisingly well.

If I can find the funding and the time, I'd like to re-run the trials using various types of stone for a better comparison.

Having said all that, DT does have an excellent and well-deserved reputation. I wouldn't discount it based on just one trial.


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alrat
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Posted: 05 April 2019,08:35 QUOTE

I asked Lithofin which of their products they'd recommend for Silver (sesame) granite and they said MN Stain Stop W.  Seemingly it's only slightly less effective than it's solvent based big brother at protecting, but it's less problematic with moisture ingress from below.

They also mentioned that no impregnating sealer will protect against acidic damage, staining from berries and red leaves being the example of exactly what I wanted to protect against.  But I kinda knew this anyway.  As discovered yesterday, I also need to protect agaist bird poo, I suspect this would be an issue too.  I kid you not, an ostrich (wink) must have flown over from africa and deposited its load.  

I've read granite is naturally quite resistant to acid damage anyway.  However flaming the surface increases water ingress and any other liquid based staining, so I guess the impregnator goes some way to restoring this resistance.  Hopefully it will help against algae and moss.

It makes me wonder how well an impregnator, Lithofin or Dry Treat, will help protect against staining from jointing with a sweep in product, either on the surface or the sides for picture framing.  Jointing compound manufacturers seem to insist on sealing before using their products, perhaps they mean with a surface sealant rather than impregnator, which I want to avoid at all costs.
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Tony McC
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Posted: 06 April 2019,18:56 QUOTE

The type of stains you mention have always been a problem, but a good imp. sealant will offer basic protection *as long as the stain is cleaned within about 24-48hrs*. Much longer than that and the tannins and erythro-wotsits seem to find a route into the stone.

You also have to bear in mind that some granites are VERY porous and others are hardly porous, I think some of the one-part mortar manufacturers are pushing pre-sealing because of the cheap dopping oils they use which lead to picture framing on "fairly" porous stone, whereas the good quality 2-part mortars can cope on "fairly" porous stone *as long as the stone is sodden*, abso-bloody-lutely saturated with water before applying the mortar, while the very porous stone (so G603 and the likes) do fare better if pre-sealed.

I'd be very reluctant to issue blanket advice, as there is SO much variation in stone, even amongst stone that is asaid to be the same stuff (look at how variably crap Fossil Mint can be - from crap, to totally bleeding crap!), and then you have to factor in the competence of the installer. I wish I had a quid for every time a user of a slurry mortar has LIED to me by claiming the surface was throroughly pre-wetted when the evidence staring both of us in the face tells me it most definitely wasn't!


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