Question
Hi, i have just had a patio laid with a natural stone.  The landscaper used an acid wash to brinfg out the colour etc.  Would you suggest sealing the patio as well? What benefits does this have? And can it be done straight away?

Thanks

Answer
Sealing is ALMOST always a good idea if the stone is mortared in place. It will make the colors much darker and vibrant. To get an idea of how this will look, wet the pavers. It also helps prevent mold and frost cracks by stopping or minimizing water infiltration.
However, on a pool deck or places toddlers play it can be a very bad idea. Sealed stone has a tendency to be MUCH HOTTER  and slicker than unsealed stone. It can be literally too hot to walk on in bare feet. It can burn you on really hot days. Specially if the stone has lots of darker colors. It is also very slippery when wet.

You should wait a few days minimum before applying, a couple of weeks would be even better. In my experience it is best to use an oil based sealer. I like a brand called Rez-Seal. You roll it on with a thick nap roller. Be sure it is very clean and very dry (it needs to have not rained for several days and no water been applied during that time. I would acid wash, rinse, then dry for three days and then thoroughly broom/vaccume it just before applying. Do not apply on a windy or overly humid day...see can for instructions.

http://www.euclidchemical.com/product_detail.asp?id=53&pselect=222
purchase at a local masonry store, you may have to order it or find a equal with similar characteristics. I doubt if local home store will carry it.

Use the matt or flat finish unless you want a glossy look. You might want to add a bit of fine sand or non-slip additive to be sure it isn't too slippery when wet. You can literally lightly sprinkle this in the the wet sealant right after applying. I use a salt shaker. Or some installers add it to the can of sealant. Follow recommendations for store bought non-slip additives.

I recommend you get a piece of the same stone and apply the sealant to see if you like the finished look before applying it to a large area.

Best of Luck

Sean J Murphy, LA
Director Planning and Landscape Architecture

SEI
Southeastern Engineering, Inc.
Amenity Architects, LLC

www.seengineering.com
www.amenityarchitects.com