Maybe Saturday night's not the best time to ask but would anyone be able to advise on the time ARDEX-FLEX FS needs to dry before sealing? The bag doesn't say other than that it's walkable after 5 hours. But I don't want to walk on it - I want to put the new sink in the worktop and start on a week's worth of washing up. Technical Data on the website says Final Set (Vicat) approx 4 hours and gives Brinell Hardness figures up to 7 days. So would that be 4/5 hours or 7 days before I can seal it?

The grout's been on for a touch over 48 hours now and I was thinking of sealing it tomorrow/today. However, Google now tells me people are saying to leave grout for 30 days before sealing. I know I could ring ARDEX on Monday but that's Suday gone.

(Background, if relevant, is that 25 years ago I put a tiled worktop all round the kitchen - seemed like a good idea at the time and nobody said otherwise - and suddenly that rusting sink needed changing. Because I've still got half a bag of ARDURIT F4 and a drop of ARDION 101 in the shed I assumed that was what I'd used in the first place. Apparently ARDEX-FLEX FS does the same job all in one now so thinking maybe 25 years shelf-life might be pushing it a bit, off I went - lifted a few tiles, cut a bigger hole for the new sink, chipped out all (well, most of) the old grout and regrouted with the new stuff. Now I'm not so sure that was actually what I did use because the surface seems a lot rougher - hence the sealer.)

The other option seems to be, according to Google again, to silicone the joints, put the sink in and not make too much of a mess until the 30 days are up. But I would have thought it would be more effective to get the sealer on before all that so the grout is sealed well under the sink and silicone. After all, I want this to last at least another 25 years!

Any advice gratefully received.

I use Ardex Flex-FS grout quiet regularly. On floors, it is set to light foot traffic in around 2 hours, likewise you can silicone a bathroom after a couple of hours too. You need to give a wet area, such as a shower cubicle at least a week before using as the grout is still achieving is fully dried state and could become compromised if made wet too soon.

In your application, I'm not sure why you need to seal the grout or what you intend to seal the grout with? For work surfaces you should really use epoxy grout as this is the only grout recommended for high hygiene areas.

Thanks, Captain Slow. It's become very clear that it wasn't the Ardex in the shed that I used all that time ago. I did think when I chipped out the old grout that it was harder than expected - and certainly wouldn't have been touched by one of those B&Q grout removing tools I looked at - so I expect it must have been epoxy grout, if that was around 25 years ago.

But having regrouted with the new Ardex and finding the surface nowhere near as smooth as the old one I thought maybe rather than take it all out and start again (there's about 500 two and a quarter inch tiles involved) I could get away with sealing it. So I looked into sealers and was advised that HG Super Protector would do the job. I can see it still won't give a smooth surface, being a penetrating sealer, but hopefully the tea stains would clean off rather than soak in. Food preparation is all done using boards or plastic mats on top of the tiles so we'd be no worse off there.

I'd be very grateful for your advice as to whether the sealing really would do the job as far as avoiding stains. If not, I'll have to start taking out the grout again tonight - although that will be easy compared to the last time. Epoxy grout seems a lot trickier to put on than the regular stuff but if that's what I did all that time ago then I expect I can do it again - it's only my memory that's failing. At least, that what I like to think.

HI..

All the sealer will do is give a flash time to get the tea etc wiped up..

You can however use a grout colourant that is epoxy based and will leave the joints impervious to staining.

Very easy to use.. just the same really as applying the sealer.

Aqua mix grout colourant from Trade tiler.. TradeTiler.Ltd Grout Colorant

[ame=http://www.youtube.com/watch?v=m7BTYdRa9Tc&feature=player_embedded]YouTube - Tradetiler Aqua Mix Grout Colorant Application[/ame]

Thanks very much, Dave. That's brilliant.

I'm now very pleased that Ardex didn't say on the bag how long to leave it (they tell me it's been ready to go since a couple of days back) otherwise I'd have gone for the HG.

Expect to hear from me again with the same question in another 25 years - or maybe even longer if the eyes go the same way as the memory. Tea stains? What tea stains?