Pointing Indian Sandstone

[colin H]

Hi Folks ,

Can anyone advise me on the best method for pointing indian sandstone flags . I dont mind taking my time and using a small trowel , but wondered if a mortar gun would be useful ? I`m a bit wary of them , as Ive heard its difficult to get the mix right .

I`m a bit concerned about getting the mix on the surface . Is it easy enough to wash off with clean water , or will it stain .

I thought i`d use the same mix as my mortar bed ie 4 -1 mix of building sand / cementwith a bit of plastisiser - does this sound o.k. or do I need any additives .

Any advice at all will be much appreciated .

 

[r896neo]

4:1 would be fine. The guns are quicker once you have the knack of it. If its more than 25 metres then go for a gun.

If pointing by hand i prefer to mix it a tiny bit damper than needed then throw it out on a wooden board to dry out for 20 mins. It always makes better mortar than trying to mix semi dry as it never mixes that well.

It should be dry enough so as to not leave marks but an stains just keep a paint brush/ sponge and dip it in water and clean them off beofre they dry.

 

[ladylola]

I've found it's worth investing in one of these small tools for this sort of job-
http://www.ebay.co.uk/itm/1-X-NEW-S...907?pt=LH_DefaultDomain_3&hash=item4d0337619b

 

[colin H]

Thanks for the advice .

Ive around 20M to do - so I might shy away from the mortar gun !

I pointed my gable end a couple of years ago and found the best method for me was to point as well as I could , then finish it off with a damp sponge - so I`ll probably use the same method , especially with the stone edges being irregular !

Also , am I right in thinking that brick acid is a no-no for removing the excess due to it reacting with the sandstone ?

 

[r896neo]

No acid on sandstone!!

The sponge technique will give you smearing as the riven surface is not like a smooth brick.

The consistancy is the key but as you have done some pointing you'll know its much the same.

I prefer to use plastering sand as it holds less water and so doesn't stain as easily. I also thing it gives a harder joint but that's open to debate.

 

[lasors]

Ultrascape flowpoint grout. Applied as a slurry, flows into every crevice and goes off in 30mins. You can't use too much water. Brush off final excess and it leaves no residue on the stone.

It's over £20 a bag but it's easy and fast and it works. EH Smith stock it.

 

[geraldthehamster]

Thanks for the advice .

Ive around 20M to do - so I might shy away from the mortar gun !

I pointed my gable end a couple of years ago and found the best method for me was to point as well as I could , then finish it off with a damp sponge - so I`ll probably use the same method , especially with the stone edges being irregular !

Also , am I right in thinking that brick acid is a no-no for removing the excess due to it reacting with the sandstone ?

Brick acid is a bad idea but not necessarily a long-term disaster. I had to use it on some sandstone that a builder laid for me as part of larger works. He managed to smear the mortar used for pointing all over the surface. Brick acid reacts with iron oxide in the sandstone and turns it various shades of orange. However, within two years the extra redness had washed out with the weather. How patient are you ?

Cheers
Richard

 

[Philip Edwards]

I have just had laid 40m2 of Indian sandstone path/patio with double cobble edging. The cement hasn't totally stuck the slabs or cobbles. Am I safe to point? If so, what's the best stuff to use.

 

[lasors]

If there's any movement in the slabs then pointing is a waste of time, it will crack and loosen with use and will eventually fail.

 

[Philip Edwards]

Thank you for replying. What would you suggest I do to rectify this issue?

 

[lasors]

Unfortunately, if you want it to last, take it up and do it again, at least the slabs that have any movement.

Prime the slabs before laying them to ensure good adhesion. Use slurry pointing which will flow into any little voids and give the slabs as much support as possible.