Pointing Gun ??

[Rick Hughes]

I have a 175 sq m of Indian Sandstone patio ... after 2 winters some of the pointing is now missing and/or crumbling away.

I know I could just rake it out and re-point with semi-wet 4:1 mix, pack it in, tool it up ...

However is there a better way ... I know there are pointing guns ...anybody here used one and find them any good, want to get first hand experience response form someone who has used them.

A local builder advised they are useless, as to get mix wet enough to pump out, it would separate and drip everywhere. In fact he just gave me his gun to try ... still boxed with assorted nozzles ...

there any mixtures, additives etc., that improve the mix, better for pointing etc.

[Andrew Gabriel]

I would guess you want a much weaker mixture than that for pointing sandstone which I believe is very soft, but I've never pointed it myself.

He's right.

Yes, but nowhere near enough to work in a gun.

Get someone to show you how to do it properly. It's not difficult once you know. (It is difficult to describe though - you need to be shown how to get the mix right, and how to handle it with trowels, and how to finish off.)

[Steve Firth]

similar gun and it vastly speeded up the work. There's no need to make the mortar sloppy and I was working with a coarse sand to match what had gone before. you still need to smooth over the mortar with a frenchman. It's not a wonder tool but is useful for some jobs.

[newshound]

Never used one on a patio, but definitely good for random stone house and garden walls: lets you fill up deep cracks and voids.

[Rick Hughes]

I know how to do it - watched it all going in ... it's just the time it takes with a gauging trowel ..

[Roger Mills]

I've always been sceptical about these guns, but I've jut watched someone using one - and it looked very quick and easy. Of course, doing it oneself might be a different matter!

I've just had a drive re-surfaced in tarmac, with a row of paving bricks right round the outer edges. The people who did it used a pointing gun to point between the pavers. I quizzed them about what they were using in the gun. They said it was a strong mix (2:1 I think) made with "plastering sand" - whatever that is - and with plasticizer added to make it flow. From what I could see, they were using two barrels with the gun and, while one bloke was doing the pointing, another bloke was re-filling the other barrel. They were mixing the mortar in an electrically driven mixer - and it had the consistency of whipped cream. It certainly wasn't excessively wet - but it flowed far better than I would have dared hope. I did get the impression that it takes a little while to develop a suitable technique!

[stuart noble]

Sounds like the additives may be excessive, probably to the detriment of the finished mortar.

[dent]

I've got one of these:

pointed an extension, and the surrounding patio with it. Very easy to use.

As you squeeze the mortar out, some water does separate out, but very little. As a result of this water loss, the very last bit of the mortar in the tube will be a bit dry and harder to use, so I got into the habit of refilling the tube with fresh mortar once I'd got near that point. Really it's not a problem though.

Add hydrated lime. It makes the mortar much more workable.

dan.

[Dave Liquorice]

2:1! I wonder how long that will last before it cracks and falls out? The "plastering sand" (what ever that is) might make a difference but I'm not convinced. Too much plasticiser will also weaken the final result but you do have to seriously over do it.

[Jonathan]

It's a mix of sharp sand and ordinary builders' sand. It makes stronger joints. it is designed for rendering but I use it form most things.

Jonathan

[Rick Hughes]

On a separate forum was told that the dogs spheroids to use is 'easipoint' ... they have a video on their website ...

it's around £25 a bag .... so may not be a cheap solution - but it does look easy enough to use.

[Mark]

No it is not, plastering sand is a fine sand sieved to uniform particle size, you really don?t want the small pebbles you get in builders sand when polishing off the rendering on an external wall.

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[Dave Liquorice]

I do love the way everyone knows what everyone is unambigiously talking about in the building trade. B-)

"Building sand" to me would be "soft sand" and be fairly uniform rounded grains, no pebbles. Small irregular pebbles I would expect to find in "sharp sand" with a range for grain sizes from dust to pebble, and not all rounded.

[Mark]

you really dont t want the small pebbles you get in builders sand or the even bigger ones you get in sharp sand when polishing off the rendering on an external wall. better ?

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[The Natural Philosopher]

I rendered my house in sharp sand. Looks much nicer.

[Tony Bryer]

I wouldn't expect any pebbles in sand - sharp sand is much the grain size of granulated sugar, soft sand much finer with a certain amount of clay (?) in it. There's another grade of sand whose name escapes me which is clean sand like sharp but much finer: would make good rendering sand but horrible for bricklaying.

[stuart noble]

I don't believe anyone who isn't a plasterer by trade can make a good job of rendering a whole house. May look much nicer to you :-)

[Rick Hughes]

OK ... some actual facts rather than here say -

The original spec for sands was BS 1200, and the later standard of BS EN

13119 (aggregates for mortar) and BS EN 12620 (aggregates for concrete)

Summarised as:-

Builders Sand / Soft Sand - can be dug or dredged. If dredged it is washed, must be of small uniform grains, Finely graded to BS 1200 from dust to 4mm particle size .. contains no clay.

Soft Pit sand - as for Builder sand - but dug out Limestone, providing smaller more consistent grain size, finely graded to BS EN 13139 - much loved by bricklayers.

Fine Washed Sand - sieved soft sand, more consistent particles size - typ used for plastering - to BS EN 13139

Sharp Sand - typ dredged sand with larger proportion of sharp aggregates

- typically shell, to standard BS EN 12620

Medium - Fine sand, formulated sand to suit rendering & plastering to BS EN 13139

[Mark]

which are all out of date and superseded

however Plastering sand is= "Fine - sieved soft sand, more consistent particles size" not builders sand or sharp sand or a mixture of both!

yes of course you could render a wall with sharp sand or even with 10mm shingle mix, really depends on the finish you are after. but you will never _polish smooth_ a wall with sand that has a high percentage of larger sharp aggregates.

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