I have just has a patio put in, with dark sandstone slabs.

The firm who laid it were supposed to point it up properly with wet
mortar, but instead they decided to brush dry mortar into the gaps and
let it go off over the next few days. The company supplying the stone
psecifically advise against this because of staining.

My concern is that this left a fine dusting of dry cement over tha
slabs. It then rained a bit, enough to wet the cement but not enough to
wash it off. I thought about hosing it down, but that would probably
have washed the mortar out of the joints.

The slabs now seem dulled, probably they have a very fine cement
coating. Will this weather away over the next few weeks or is there a
serious problem?

wrote:
I have just has a patio put in, with dark sandstone slabs.

The firm who laid it were supposed to point it up properly with wet
mortar, but instead they decided to brush dry mortar into the gaps and
let it go off over the next few days. The company supplying the stone
psecifically advise against this because of staining.

I'd always dry point to avoid staining. Wet mortar is much more likely to
stain the slabs. Standard proceedure is to brush in dry mix, run a pointing
tool over the joins, brush of the excess.

My concern is that this left a fine dusting of dry cement over tha
slabs. It then rained a bit, enough to wet the cement but not enough
to wash it off. I thought about hosing it down, but that would
probably have washed the mortar out of the joints.

They should have swept/brushed most of it away, but some residue is bound to
remain.

The slabs now seem dulled, probably they have a very fine cement
coating. Will this weather away over the next few weeks or is there a
serious problem?

I don't think it's a serious problem. Any coating that fine won't survive
long.


--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

The Medway Handyman wrote:
wrote:
I have just has a patio put in, with dark sandstone slabs.

The firm who laid it were supposed to point it up properly with wet
mortar, but instead they decided to brush dry mortar into the gaps and
let it go off over the next few days. The company supplying the stone
specifically advise against this because of staining.

I'd always dry point to avoid staining. Wet mortar is much more likely to
stain the slabs. Standard proceedure is to brush in dry mix, run a pointing
tool over the joins, brush of the excess.

With some floors it is necessary to seal the tiles properly and that
means a wet mix. What you then do is cover a section of the still wet
floor with straw or saw dust and get on your hands and knees and polish
it off.

If you strew it all over the floor, the danger is that the grout will
dry out before you can get to it, to polish it.

It is a quick enough job once you get into it. But a drudge if you over
reach yourself.

In the case of the OP I'd check my contract and if they broke it, stop
the cheque and wait for the boss to send someone out to inspect it. Of
course this IS a diy group -so if I was the OP I'd have more sense than
to post to a group of people who are likely to tell you that it serves
you bloody well right.

Serve him bloody well right.

wrote in message
oups.com...
I have just has a patio put in, with dark sandstone slabs.

The firm who laid it were supposed to point it up properly with wet
mortar, but instead they decided to brush dry mortar into the gaps and
let it go off over the next few days. The company supplying the stone
psecifically advise against this because of staining.

My concern is that this left a fine dusting of dry cement over tha
slabs. It then rained a bit, enough to wet the cement but not enough to
wash it off. I thought about hosing it down, but that would probably
have washed the mortar out of the joints.

The slabs now seem dulled, probably they have a very fine cement
coating. Will this weather away over the next few weeks or is there a
serious problem?


The traditional solution to this is brick acid but I would not try it on
natural stone because it can cause severe staining by attacking the iron in
the stone. You could try pressure washing and the sooner the better, taking
care not to go into the pointing.

Have you tried http://www.pavingexpert.com/ - they have an excellent forum
too

wrote:
I have just has a patio put in, with dark sandstone slabs.

The firm who laid it were supposed to point it up properly with wet
mortar, but instead they decided to brush dry mortar into the gaps and
let it go off over the next few days. The company supplying the stone
psecifically advise against this because of staining.

My concern is that this left a fine dusting of dry cement over tha
slabs. It then rained a bit, enough to wet the cement but not enough to
wash it off. I thought about hosing it down, but that would probably
have washed the mortar out of the joints.

The slabs now seem dulled, probably they have a very fine cement
coating. Will this weather away over the next few weeks or is there a
serious problem?

I had precisely this problem when I tried the dry brushed method - I
simply tossed a few pints of brick acid all over and scrubbed away with
a stiff broom.

Yes, it does attack the joints as well, but they are a lot thicker. If
you are really picky use a nail brush, rubber gloves and do it bit by
bit on your knees.

Hzatph wrote:
wrote in message
oups.com...
I have just has a patio put in, with dark sandstone slabs.

The firm who laid it were supposed to point it up properly with wet
mortar, but instead they decided to brush dry mortar into the gaps and
let it go off over the next few days. The company supplying the stone
psecifically advise against this because of staining.

My concern is that this left a fine dusting of dry cement over tha
slabs. It then rained a bit, enough to wet the cement but not enough to
wash it off. I thought about hosing it down, but that would probably
have washed the mortar out of the joints.

The slabs now seem dulled, probably they have a very fine cement
coating. Will this weather away over the next few weeks or is there a
serious problem?


The traditional solution to this is brick acid but I would not try it on
natural stone because it can cause severe staining by attacking the iron in
the stone.

Its fine on sandstone. You may get some leaching of manganese - I have a
puddle of red manganese salts - but these wash away in time.

Its a disaster on limestone of course..and concrete flags...but its OK
on slate also.


You could try pressure washing and the sooner the better, taking
care not to go into the pointing.


Not good if the cement has dried. Brick acid first, THEN pressure wash.

Have you tried http://www.pavingexpert.com/ - they have an excellent forum
too