Lime pointing

[markbrick]

Hi there everybody,

i am a bricklayer and was looking for some info on lime pointing, i have a boundary wall to rebuild and am required to flush point it to match the house, its a sharp sand and lime mix by the look of it, the house is about 50 years old , does anybody have any experience of this? and know a suitable mix and what type of lime to use, and the technique? i believe this type of pointing was quite common in london .

many thanks

Untitled

• markbrick
• 26 Nov 2009
• 1

Untitled

• markbrick
• 26 Nov 2009
• 1

 

[amwc]

Hi

you want to use hydraulic lime in a mix 1 : 4. If you troweling it in, which is probably the best way to do it, you need quite a stiff mix that should be easy to compress in your hand and easy to break up back into a mix. once you trowel it in you can finish it with a piece of batton cut at 45 degrees to get a flush finish then leave it half hour or so and stiff brush it off. they used to do what was called a bag finish instead of brushing with a hessien bag. The hydraulic lime is a substitute for the lime putty that no one likes using as it never goes off and has loads of health and safety issues with it.

 

[stuart45]

Mark,
can you put a photo on of what you are trying to match to?

 

[lostinfens]

Personally I use lime putty - the shop bought variety made from quicklime & find it very user friendly. A cheaper option is to make your own from bagged lime soaked for a few days in a bucket, not for the purists, but I think it works quite well.
If your worried about it going off then use a pozzolanic, I've used crushed cinders & fire ash to good effect. The other advantage of this is that it tones down the lime mortar a bit. Lime putty tends to finish quite light & can stick out like a sore thumb, so I would use something to tone it down, even a small amount of dye or soot, but test the mix first. I wouldn't use cement, the mix will harden sufficiently to weather proof.
You're supposed to mix the sand & putty, leave it & knock it up again before using. If not then pay attention to any shrinkage, which will occur. The pointed finish depends on what you're matching- a finger trowelled struck pointed then distressed looks the business I think.

 

[lostinfens]

I just noticed that you mention the house is 50 yrs old. Are you sure its lime mortar? I'd have thought not by then- is it cut & struck? I lived & worked in London & Middx, they were mostly pointed that way I remember.

 

[stuart45]

50 years ago weather struck and cut pointing was popular in white cement mortar (with some added lime) which looked like lime as lostinfens stated.

 

[markbrick]

I just noticed that you mention the house is 50 yrs old. Are you sure its lime mortar? I'd have thought not by then- is it cut & struck? I lived & worked in London & Middx, they were mostly pointed that way I remember.

im sure its a lime mix and its a flush finish

 

[markbrick]

Mark,
can you put a photo on of what you are trying to match to?

photos added tonight

thanks

 

[amwc]

Hydraulic lime grade 3 and hanson 50/50 sand wont be far off that.

 

[lostinfens]

It looks a bit too full for 50 yr old pointing, either that or it's stood the test of time well. Looking at the second picture it appears to have been repointed, possibly in a lime or lime/sand/snowcem mix. Either way try a bit and see.

 

[stuart45]

Try this site for a match.
http://www.lime-mortars.co.uk/lime-mortar/hydraulic-lime-mortar

 

[markbrick]

Hydraulic lime grade 3 and hanson 50/50 sand wont be far off that.

thanks for your reply , i havent used hanson 50/50 before could you explain it? i looked on hansons website but couldnt find it.
thanks
mark

 

[stuart45]

The right sand is important for the colour. You can find out what sand was used by putting in some of the original mortar in acid which will leave you will a sample of the sand.
Using a 1/1/6 cement/lime/sand mix with 50/50 OPC and white cement mixture will give you an older looking lime coloured mortar.

 

[amwc]

Hi
Sorry, the Hanson 50/50 is a mix of 50% soft sand and 50% sharp sand it enables you to rub it in nice and smooth but looks rustic once brushed. it is also a nice colour not too orange. not far off what you've posted


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