# Forum Home Renovation Brickwork  Lime Mortar Recipe

## Micky013

Hi 
Just wondering if there is a standard Lime Mortar mix for repointing brick work and stone? Also, what is the natural colour of the mix? same as cement mortar? If colouring is required, is it just a matter of using oxide? 
Im looking to repoint quoin work which is red brick and some stone walls which appear to be a sand stone. 
Any tips would be much appreciated! 
Cheers
Michael

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## intertd6

Lime mortar is a thing of the past as the supply of un hydrated lime is not common now, cement mortar with hydrated lime is the norm now & the lime is used for plasticity & workability. Mixing ratios are usually on the sides of the bags, normally 1:1:6    sand:lime:cement
regards inter

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## Micky013

Thanks Inter. 
Would that apply to buildings that we originally built with traditional lime mortar? I have read that the use of cement can or will cause damage to the bricks (as they are not fired as hard as modern bricks). 
I've done a bit more research and have found some articles that use hydrated lime and sand as a replacement for the traditional lime mortar. It still takes a while to fully cure but doesn't use cement (as the hydrated lime has impurities that are essentially cement in some form). 
Thing is, I cant find two articles that mention the same mix ratio so that leaves me a bit hesitant to just wing it. 
Cheers
Michael

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## johnc

You need lime putty, i wouldn't make a bricklayers rear oriface but if you are doing conservation work you shouldn't use modern mortar on old lime mortar as you will ultimately damage the brickwork over time. try this link and see how you go. How to tuck point Mixing lime based mortar/ Mortar Color Matching - YouTube  The one thing I would mention is you need to be careful, with the mix done properly there is a lot of spitting and spluttering while the lime mortar is cooking.

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## an3_bolt

General repointing I use a mix of 2 parts sharp clean sand to 1 part drained lime putty (by volume). 
Sand free from impurities such as clay etc. 
Sand colour to suit - but generally white, light grey and golden will still produce a fairly white final result. Oxides to tint as required. 
If you want to find the true colour of your mortar - scratch it back 1/4 ". Matching can be a pain - and may require many samples. It can also be an issue of match the original or match the faded old stuff...... 
Lime putty is still available - in Melbourne - was several years ago - think Vitale & Sons used to stock it. Needs to be drained prior to use - and no need to add water - thrixotropic mixture - will be hard going but ramming and pounding/chopping will do the job. Correct texture is like a fetta cheese/riccotta cheese - will stick to the back of your trowel easily and you should easily be able to turn it upside down and not come off. Too soft - you will smear it all over your brick face. 
The compo mix (1 cement/1 hydrated lime/ 6 sand) is a usefull replacement for things such as bricking up doorways, re-laying bricks etc. In terms of repointing - if there is any movement in the building (ie many houses such as my own have a simple footing of brickwork on excavated clay - and as a result continually move with the ambient conditions of the surrounding substrate) - will crack and fail at some stage. The lime mortar worked very well with these early style footings - able to accommodate some of the flexing, and to some degree self healing. 
No need to use any burnt lime/rocklime. Just get the bags of lime putty. Just note that on one of the bags a used a few years ago - it suggested a mix of 3 parts sand to 1 part lime. From my research in the bowels of the British Library in London and the analysis of my own property - is most probably inaccurate. The old old 3:1 appears to come from the use of rocklime in the making of hot moratar mixes (ie the lime is slaked in situe with damp sand then punched through a screen for later use. In effect a partially slaked lime). It is the expansion of the lime that gives the approximation of a 2: 1 mix by volume if using a fully slaked lime. So if using a lime putty - 2:1. 
Cheers

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## Micky013

Thanks an3_bolt! 
That is exactly the type of info I was after. I will look into stockist of lime putty here in SA (unless someone can tell me). 
I saw you mix ratio for general patch ups - I used a 1:3 mix ratio (cement:sand) to patch up a few loose bricks in the door ways (down the bottom). Should I be worried now that I have actually done some research and know the effects of using cement in such an old building? we're only talking half a dozen bricks max in one location. 
Cheers,
Michael

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## an3_bolt

1:3 cement sand is pretty heavy going for anything! 
However - those bricks not going anywhere. The bricks will crack before the mortar does. 
If it was me - If they are not soft bricks, and it is not in an aesthetically detracting position - would most likely do more damage removing them and finding replacements than just leaving it be. Bit hard to tell in just text about the situation and what final result you are trying to achieve - But I guess a picture is worth a thousand words.  
I am sure some one in SA stocks the lime putty - try plaster supplies as it is used in white setting / gypsum-lime plaster. I also imagine Heritage SA would know who stocks it. 
Quick add - 5 sec search on Lime Industries website indicate that in SA the distributor is at Thebarton http://www.limeindustries.com.au/for...butor_list.pdf

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## Micky013

Thanks mate, thats golden! 
I dont know if i got that mix ratio from somewhere or if i just made it up. They will mostly be covered by skirting anyway. I was just concerned about wall/plaster cracking.  
Cheers 
Michael

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## Micky013

Just on a similar note - I salvaged a couple thousand bricks from the old leanto. These would have been from the same time period as the house, being 1905 ish. 
Is it ok to lay them using the 1:1:6 mix (cement:lime:sand)? (for bbq, raised garden bed etc?) 
Should expect damage to the bricks using this method? 
Thanks guys - i just dont know how temperamental these bricks are to normal building methods.

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## intertd6

It should be ok, the idea is for the mortar to always be weaker than the masonry, chances are that the bricks are better & more durable than what you can purchase now.
regards inter

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## Micky013

Thanks inter!

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## autogenous

The principle of mortar weaker than the product is that it doesnt crack through the product.  Engineering of the past was based entirely on compression. 
Non-hydraulic mortar can be woken up. 3 sand to 1 Lime putty is general mix. Sand colour will determine the colour. 
Cement based hydraulics work on heat and cant be woken up; dry much faster making them harder to work with. 
While we discuss 3 in 1 non-hydraulic mortars, in many cases there was other additives such as cellulose based water thickeners and in some cases slakers that had quarried surface limestone inadvertently mixed in loams in the process which gave extra strength. 
Be sure to brush your medium prior with a little water to create a mechanical connection pending the stone isnt moist already.

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## GraemeCook

Good Morning Micky 
The 1:1:6 lime-cement-sand ratio is probably about right - it worked fine on the 130 year old soft convict brick walls and sand-stone foundations at my place. 
However, it is critical that the new mortor must not be harder than the old mortor otherwise damage to the original work may result.    
An old retired brickie friend, no longer with us, guided me through the repointing.   Even though he had 60+ years experience he still mixed a trial series of mortors before every job - "all sand varies, all lime varies and the mortor you are matching varies.  You cannot guess."   He mixed three trial batches (each about a cup full);  one with the 1:1:6 ratio, the others with the same amount of lime and fat sand, but with 20% less cement and 20% more cement.   Next morning he matched them against the existing mortor and chose the ratio that was just slightly softer than the existing mortor.   I was surprised how soft the chosen ratio was.   He then ensured that I measure the ingredients very accurately. 
One trick, he added a squirt of washing up detergent to the mixture.   It improves the plasticity of the mortor.   
Fair Winds 
Graeme

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## autogenous

Adding aeration agent is not advisable. Aeration agent forms a honeycomb like aero bar which weakens the mortar to varied degrees for a number of reasons.  
If you want to use a 9 sand, 2 lime, 1 cement mortar.   
Sometimes in some countries an aeration agent content is used in 'high' loam/clay sands but the mix is 4 sand 1 GP cement.  
The other is where you may be using washed white sand which is course as hell and has relatively no loam. You literally cant get a workable mortar in a 6:1:1 mortar with the large aggregate white washed sand; WWS is horrible laying bricks, worse than plasterers sand. In that case you might add half a teaspoon to a mix in the water first but for the most part aeration is completely banned in some states. 
Micky, you can lay the bricks in 6:1:1. Have you picture of what your repointing? Stone and Brick.   

> Good Morning Micky 
> One trick, he added a squirt of washing up detergent to the mixture.   It improves the plasticity of the mortor. 
>  Fair Winds 
> Graeme

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## Micky013

Thanks a lot for all your comments guys....This is something I have found quite interesting lately and I cant find enough vids to watch on Youtube and blogs to read about on the subject. 
Here are some pics (not the best, but all i have on my phone ATM). Its red brick with a sand stone on the sides but what has been described as "freestone" on the front. It looks like concrete but has streaks of light and dark grey which make it look stone like. I dont know exactly what it is and a couple brick sales reps didn't either. They're large blocks which seem reasonably soft. Since this front shot, I have stripped 90% of the paint off the brickwork. 
My ideal plan would be to rake out 10 - 15 mm from all joints and repoint the whole thing - so matching isnt such an issue. The only side that doesn't need re pointing is the one that's protected from the weather. 
Please let me know what you think.... 
Cheers.

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## Micky013

By the way, i made that top sash from scratch. I did post about restoring this ages ago. For anyone who read about it - this is the end result.

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## GraemeCook

> Adding aeration agent is not advisable. Aeration agent forms a honeycomb like aero bar which weakens the mortar to varied degrees for a number of reasons.

  
This may be quite true. 
But since when has a wetting agent and plasticiser such as a detergent been an "aerating agent".   Some rather basic chemistry needs changing. 
So that I do not make the same mistake again, if it was a mistake, then perhaps you could quote the ANZ Standard or building code reference that bans the practice.   
Thanks 
Graeme

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## intertd6

Adding plasticiser aeration agent to cementious products actually makes it more flexible & durable, especially in freeze / thaw situations, when you think about it brickies will lay some masonry units on just sand if it is to be removed at a later date, so compression strength wouldn't really come into it.
regards inter

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