Seal before or after laying?

[David 1234]

I have some very pale Indian Sandstone, not dissimilar to Stonemarket Mirage. Given the absorbent nature of this pale stone I am thinking about sealing it prior to contractor - hi Dan - laying it.

Manufacturers such as Lithofin and Hagesan, recommend sealing prior to laying, to avoid dirt absorbing whilst doing the job. However, the consensus amongst contractors is to lay, and leave it till Spring, and seal when dry.

HG Hagesan Natural Stone Impregnator states that dampness in the stone can still evaporate and on this basis their technical department believe that efflorescence won't be a problem. Lithofin are insistent that laying now unsealed is a bad idea as the weather won't be warm enough till Spring and the stone may become stained before then.

What do you think?

[Pablo]

Tough choice personally I would I would pre seal them with a water based sealer and then re seal them in the spring with your final coat. A water based sealer doesn't need warm temps and it doesn't matter if the paving is slightly damp. I use Aqua seal from Tobermore and usaully use Larsen Acriseal for my final coats in better weather. The problem with light flags is that you can seal them all you like they'll still get very manky very quickly unless they are in direct sunlight from early morning onwards even then it's no guarantee. If the area is only small then perhaps seal them before laying (both sides)otherwise lay them and seal in 6-8 weeks. With regards getting dirty during installation any decent contractor shoud keep things clean as they work through the area and clean their feet before they walk on it etc. When the flags are damp and wet during installation it actually helps with keeping them clean we keep a hose on hand to keep them wet if needs be.

[David 1234]

Thanks for your advice. These water based sealers - do you find they perform as well as the solvent based. I'll need durability as from what you say I'll be using the Karcher a fair bit.

[Pablo]

Water based sealer will seal them but it is invisable so it doesn't lift the colour like solvent based will. Like I said they are a short term solution until you can put the good stuff on when the weather improves. You'll need something with a bit more poke than a karcher to get them uniformly clean have you heard the expression chocolate fireguard.

[David 1234]

yep know what you mean. I recomended Roger Oakley to do my neighbour's drive complete with his 28HP washer mounted on a trailer. He did their driveway in two hours - it took me two days to do mine with my Karcher....although in the end I got a good result.