Repointing a (lot of) garden wall: angle grinder?

[PeterC]

Obvious - it might do the job!

[Phil L]

And here is where we find the downfalls of patch pointing.

Once you've targetted the 'bad bits' and repoint them, the 'good bits' that you haven't done are now the 'bad bits'.

My advice is to rake out, by hand, the whole wall and repoint the lot, with sand and cement, use measured mixes and be sure to use the same brand of cement as different brands are completely different colours. four to one will be adequate for a garden wall, wash it down prior to pointing, and on hot days, you'll need to wet it prior to starting work, a hosepipe will come in handy

[Anna Kettle]

ISTR that your bungalow is 1930s Tim, in which case the garden wall is probably built with lime mortar not cement mortar. Even if it were built with cement then the cement would be a lot weaker then modern cement so I recommend that you use a hydraulic lime / sand mortar

Cement grey will pigment the mortar quite strongly. Hydraulic lime is white so the final colour will be a paler version of whatever sand you use. If you want to be fussy, then you could get hold of a few different sands and make up samples

Anna

[Tim Watts]

On Sat, 23 Jan 2010 08:54:59 +0000, [e-mail] (Anna Kettle) wibbled:

Hi Anna,

It's a 50's build - was lime common then (with or without cement)?

I think I do agree on the possibility that whatever is in the walls right now *might* be limebased - it's too light for most cements.

Cheers

Tim

[Stuart Noble]

Not something you can just pop out and buy though. None of the builders merchants in my area stocks hydraulic lime.

[Andrew Gabriel]

I'm still using a large bag of it I bought from Travis Perkins about 8 years ago (but stored indoors in the dry).

[The Natural Philosopher]

hydrated lime is the key word.

All BM's stock it.

[Stuart Noble]

Not hydraulic though is it?

[Bruce]

Hydraulic lime:

lime:

[Tim Lamb]

In message , Bruce writes

regards

[Rod]

It is ordinary Portland cement that is white - more or less.

[Anna Kettle]

Agreed that it is not as readily available as cement, but it can be found all over the country. I suggest that either

- You tell me where you live and I may be able to suggest a supplier

- Contact a producer and ask them where you can get their product locally. Castle Cement produce a good range, St Astier is probably the largest producer

[Anna Kettle]

It is likely to have lime in and could have cement in. The big changeover from lime to cement as setting agent happened after WW2 when the priority was to build houses quickly and a generation had missed out on craft training

I doubt if liquid plasticisers had been invented, so hydrated lime would certainly be added to a cement mortar as a plasticiser

Quick setting is not a priority for garden walls, so if lime was cheaper than cement and the work was done by someone who knew about lime from before the war, then it could easily have been done with lime as setting agent and no cement.

Its not a perfect test, but extract a bit of lime from the wall and bend it. If it crumbles then it is putty or hydrated lime mortar, if it snap!s then it is hard cement mortar. Chances are that it does something in between in which case it is a weak cement or a hydraulic lime or a mix of lime and cement

Anna

[Anna Kettle]

was who named two subtly but definitely different products by names which can so easily be confused

Anna

[Stuart Noble]

Sure, I could track it down, but it's all a bit of a faff for a garden wall, especially as I wouldn't know how much I was likely to need. Until it's widely available, I don't think anyone other than conservationists is going to take hydraulic lime seriously.

[Bruce]

It is ordinary Portland cement made by a special process which minimises the content of the minerals that normally give cement (and therefore concrete) a very grey colour. Some white cements also have a white pigment added, usually titanium dioxide.

It has nothing whatsoever to do with lime.

[Bruce]

Absolutely!

It's always best to say precisely what you want to use it for, as some people selling the stuff may be similarly confused.

[Tim Lamb]

In message , Bruce writes

Right.

A fireplace restorer and our builders both used white cement when they were attempting to imitate lime mortar on new work.

I can feel Anna's lip curling from here:-)

regards

>

[geraldthehamster]

My 1963 bungalow has light-coloured gritty pointing, but I'm sure it isn't lime (or if it has lime in it, it has cement as well). When I had a window bricked up we experimented with grit sand and a proportion of lime in the cement mortar and got a close match - sorry I have no idea of the proportions used - I wanted a close match in quality also, so I left the bricklaying to a professional ;-)

Cheers Richard

[Bruce]

Mine too. Sorry. ;-)