Lime mortar question

[Lindyboo]

I’ve just opened a bucket of lime mortar that was obtained for me a couple of years ago by the garden landscapers when they worked here. I asked them to get it for me as they needed some to repoint the exposed brick on our old well and I wanted the rest to have a go at some repointing of the house.

The mortar wasn’t what I expected. It’s chalk-white and the texture of tofu until worked with a trowel then it’s like thick cream. I bunged a bit in the wall where it won’t show and it looks ghastly, like white emulsion.

This I believe is the same stuff they used to repoint the well which was a creamy colour when both wet and dry (though it fell out within a few months).
So, any ideas on what this white stuff is? Should I be adding something to it? Or should I chuck it away?

Thanks

 

[Roger H]

Sounds like a tub of lime putty. Is there any sand/grit in it?

 

[Lindyboo]

No, pure white and creamy smooth.

 

[Lindyboo]

And I should have mentioned that in the tub it's under about an inch of clear water.

 

[Roger H]

So its either lime putty, in which case, mix as much as you need with a sharp sand 1:3 ratio and use that, or else it is 'hydrated' lime approximating a putty which can still be used as above if you wish.

Opinion is divided on whether the latter - 'builders lime' - is an acceptable material or not. I've used it plenty to no ill effect and it will certainly be less damaging than portland cement.

Plenty of advice on how to point on this ite somewhere...

ps Does it say anything relevant on the tub?

 

[Lindyboo]

Not that I can see, but the tub is inside a larger tub and pressed down firmly so can't be lifted out. The landscapers did say that they had left a note inside with instructions but it's not there.

 

[Roger H]

Have a look at:
http://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=14750&p=202829&hilit=lime+mortar#p202829

 

[Lindyboo]

Thanks RogerH - lots to read up on there. I'll report back!

 

[MatthewC]

It certainly sounds like lime putty with no sand at all. I'm not surprised it fell out after your landscapers used it!!

Lime mortar will come in different shades if you buy it ready mixed, as the colour of the sand dictates the mortar colour, and I found that for external work the ready mixed mortar was often far too white. I reckon it's the colour of the building sand which has the major impact on the final colour, so I was obtained a tonne of local building sand specially from a local pit and did some test mixes. I now use something like a 2:5:1 mix of putty:sharp sand:building sand and it matches the existing on the house pretty well.

Matthew

 

[Lindyboo]

Thanks MatthewC

The original colour of the mortar here (most of which is obscured under cement mortar) is a medium-cream colour - a bit like cream with a dash of coffee - with what looks like black particles, giving it a coarse texture. Any idea what these particles might be?
L

 

[tobydog]

If you've had it a couple of years it should be good and mature by now. I've had three large left over tubs for 3 or 4 years now. It should get used shortly.

The water on the top is to prevent the putty being exposed to air. Once you've drained the water off to get to the putty, and you've finished with the putty that's left, you need to cover it over with water again and make sure the lid is tightly sealed. From personal experience I wouldn't try scooping the putty through the water otherwise you will end up with a sloppy mess. I found that the putty was already wet enough to mix with sharp builders sand without adding extra water.

If you're repointing quite deeply then you don't what the mixture too wet otherwise you'll find it hard to compress into the gap. Other more experienced people on this site have suggested a fairly dry mix which I find very difficult to get with putty. An NHL 2/3.5 mix is often recommended as a better option as that can be mixed dry to the required consistency.

As I said, there are far more experienced people than me to comment on this.

 

[TheForge]

Thanks MatthewC

with what looks like black particles, giving it a coarse texture. Any idea what these particles might be?
L

Could be ash if there's a lot of it and the mortar is a bit grey, otherwise it's probably just sharp sand 'bits'.

 

[88v8]

Lime specialists such as Traditional Lime
http://www.traditionallime.co.uk/
sell suitably graded sand.

I shall be buying some for my chimney job.

I see they also have How To videos now on that page - how to mix, build, point, render.

Ivor

 

[Lindyboo]

Thanks Ivor - what a great site. I'll be feet up with a cuppa today watching the videos (especially if the cricket gets boring, or worse, England are losing ...).
Lindy