i reuse old lime mortar in the mix whenever i can. i use a 10 sharp sand/ 4 lime mix. couple of shovels of broken up old mortar in a full mix, which is 15 sand/6lime. . makes a lovely mix and colour. i have even reused old lime mortar by itself with no new lime on a few jobs, and its set well . so far i have had no buildings fall down or walls. i am a flintknapper and been doing it for 30 years now fulltime
I use old lime for my scratch coat when plastering. Never had a problem. People think too much nowadays. Lime's meant to be simple. Keep up the good work bruv.
Thanks for the great video. How does a hot mix like yours compare in durability to a mix made of high-calcium content aged lime putty that in its putty form has matured for a few years? I guess a follow up question is when would one chose a hot lime mix compared to a traditional aged lime mix?
I think that first of all you'd need to cite your evidence concerning your claim about aged lime putty being used for pointing. Current research suggests that lime putty was only ever used for top coat plastering. It's now argued that pointing with it was an 80s revival thing - same as NHL. Mortar analysis over the last few years now provides evidence that only quicklime was used for building and pointing. Laying up putty for many months (or even years) only to be used for pointing would appear to be an expensive and unnecessary errand.
@@michaeljamesdesign , Hi Michael, my apologies. I am coming at this from the very narrow perspective of a fresco painter who uses lime plaster as a top coat, upon which I paint. I enjoy watching videos like these as they help improve my general knowledge about lime plaster. I didn't intend my comment to be about pointing, just the comparison of hot lime vs aged lime in general. In hindsight, I realize the applications (pointing and fresco plastering) are likely too different for that to have been a reasonable question.
Hi Mike, great video. Love the original pencilling. Would you put that back? I'm on a bit of mission working with Tim Meek and Nigel Copsey to restore and learn about old finishes. Just 1 little bit, I heard you say about spraying up. Don't over spray. Maybe the next day then maybe a week later. Quick lime doesn't need the spraying like putty does. Everytime you spray you re-slake. We're all in this together 👍
I don't over spray. This mortar has gone past the case hardening stage and is carbonating. So the lime can't re-slake. The mortar is subject to cold and drying winds and has some propensity to cracking. Another variable in the curing process is the amount of limestone dust in the mix. This has a pozzolanic affect which means it's prone to swifter drying. As I'm sure you're aware, carbonation, drying and relative humidity are all related.
Have you ever considered penning a book? I believe that the wealth of knowledge you possess, coupled with years of experience, deserves to be immortalized - be it engraved in stone or eloquently expressed on paper.
Thanks Stan. Yes I have. I started it but never got beyond that. I also considered a series of DVDs but they went the same way. I'm currently experimenting with insulating lime renders so will post something on them soon. If you're looking for a good read then I can certainly recommend Nigel Copsey's.
@@michaeljamesdesign Michael, your content is truly appreciated. There's a resonance with what Peter Ward presents on his channel, even though he's been on a hiatus from new posts. However, you actively implement and embody the principles he shares in his videos, serving as living proof of their effectiveness.
Thanks With portland cement mortar you can block 4 walls , 4’ high ,parge it ,fill it with water for a pool . I wonder if you did the same with lime mortar how long water would take to drain through compared to Portland cement parged pool ?
😂 , I built a garage foundation wall once , on clay , 4’ high concrete block wall with Portland cement mortar . The thing filled up like a pool after a storm .water tight I kid you not .
Hi , rather then buying 3.5 nhl premix lime mortar , can you recommend what you use , I notice big bags of white Rhino lime at large builder providers . Thanks
You say here if you are repointing old lime mortar use a quick lime. Do you mean repointing these sorts of stone buildings or do you include brick buildings too.
I always use quicklime for stone as that's what was originally used. However, I rarely use it on brick as the faces are usually porous so it stains and looks bad. It has to look nice as well as being sympathetic. I'd have no issue with it on the type of brickwork which doesn't stain. For me its putty or NHL or brick.
Mike, I have been trying to learn about limes and there uses but in the USA it is hard to find anything other than hydrated lime. My question is about free lime content that you reference. Can you explain what that is, searches do not give a good explanation and usually reference concrete. I do learn a lot from your videos any really appreciate the time you spend making them. Thanks
All limes have an available lime content. Quicklime CL90 has the highest with 90% whereas NHLs have the lowest. Compressive strength is related to the amount of free lime. This gets burnt off the longer lime it's burnt in the kiln so an NHL5 has the lowest. If you keep burning you get cement. Free lime also contributes to workability. Good workability means it takes less time to apply. So high free lime is a winner all round. When you add pozzolan you reduce the amount of free lime because pozzolan eats lime. So if you want a hard lime for exposed sites then you add pozzolan. But this is a whole other science.
I like the quick lime motar mix. Whats the make u use for quicklime and brand? Is it 1 part quick lime to 2 part plastering sand and 2 sharp sand? Why do ppl not use builders sand its like fine softer sand? Can i put sythentic as hair its hygenic?
Hi, thanks for the enquiry. There are a number of quicklimes available; the ones I use or job site specific. You'll be fine with your own recommendations for sand but again choice is as per job site. You can use building sand but it's pretty disgusting stuff. It doesn't matter when it's used with cement as this will lock in all the horrible stuff. Now do tell me, why would you desire to include man made hair in lime mortar?
I own a 17th century building here in Ireland , which I an rebuilding. The advice on lime pointing is varied and in some cases even involved cement. At the moment I am using a 3.5 Roundtower lime mixed with a portion of hydrated White Rhino lime and a plasters sand. Foe the interior. Getting a lovely workable mix. Any thoughts in case I am causing problems.
There's only one thing I'd mention and that is that Roundtower NHL 3.5 has a very low free lime content. It's only 18%. That's 82% impurities. Which is a lot. Their NHL5 contain more free lime at 25%. Personally I'd never use Roundtower NHL3.5 as it contains such a small amount of lime. Imagine eating a chicken sandwhich which only contains 18% chicken. Could you even call it chicken?
Thank you for such a quick reply. I am using a 1 -2.5 mix, but I did feel the result felt a bit hard. So I added 30% mix of hydrated lime to the lime mix. So 1/3 White Rhino 2/3 Roundtower. The mix felt really nice and has dried really well. I am taking the idea of the walls breathing very seriously and have been experimenting on small portions to get a good balance, over the past few months. Even the plastering afterwards , I will take my time, get a proper breathable mix. Thanks again for your reply, really delighted.
@@Jeremy64444 1:2.5 means you'll have more free lime but a higher compressive strength. Mixing in that much non-hydraulic lime might feel right but it doesn't necessarily mean to say that it is right. You may as well go all the way and use 100% fresh lime hydrate with a pozzolan. Personally I never mix in more than 10% - 15% non-hydraulic into my NHLs. So that means no more than 10% putty with NHL and no more than 15% lime hydrate with NHL. I never mix NHL and quicklime which is ffectively what you're doing. I take the concept of carbonation seriously. You're dealing with delicate setting processes and unless you have the backing of scientific research then you need to be careful otherwise your mixes could fail. Speaking of scientific research: there is evidence that mixing NHL and non-hydraulic lime results in the carbonation process can be slowed down dramatically. This translates to your mortar remaining vulnerable for longer. Do bear in mind that these results are born out of optimum lab conditions and these are rare in the real world. Remember, you are not a chemist.
@@michaeljamesdesign thank you, I always take advice, no damage done, as I have experimented on different small areas, will kook for a different product. Again thank you.
Hi, thanks for your vids! What do you think about nhl5 full facing harsh weather and sun any advice? The wall I’m doing is also 1700 but the pointing was done 6 yrs ago and is pouring out of the pointing crevice! Followed all your vids and feel your experience is really sound! 10 miles from your Aston cottage job! Was your South Cerney sand mix from Collimoore pit?
@@michaeljamesdesign Thank you heaps for your reply! I can bring you a few pics and some mortar from the wall next time I see you out and about! If that’s ok! I have no idea what the builders used but it’s very fragile!
It sounds very like your builders used lime hydrate. This is very good when fresh and makes wonderfully rich lime pointing or plastering mortar. However, when it's been sitting around in the bag for a while it eventually becomes inert and is only useful as a plasticiser. Hence this isn't the first time I've heard of lime hydrate mortar failing. If you want to use NHL then I'd recommend 3.5 for an exposed and weather-prone situation. Mix it 1:2.5. Just don't use Secil. I can't give you details of the sand or the blends I use. Trade secret and all that. Just don't use ordinary builder's sand.
Hi Michael , can you mix crushed lime stone 6mm grit down with hot lime ? Because I’m Finding it hard to get washed sharp sand with a grit in it . Tnx mike
Of course you can Michael. But be aware that your crushed stone will be 6mm down to dust and because of the fines it could take longer to dry out which could cause problems when it freezes if there's still a moisture content.
It would have to be a wide penny. Penny roll tends to be on brickwork. On stone it's (traditionally) called pencilling. But what's in a name. I'm not going to lose sleep over it. But then again.....
i reuse old lime mortar in the mix whenever i can. i use a 10 sharp sand/ 4 lime mix. couple of shovels of broken up old mortar in a full mix, which is 15 sand/6lime. . makes a lovely mix and colour. i have even reused old lime mortar by itself with no new lime on a few jobs, and its set well . so far i have had no buildings fall down or walls. i am a flintknapper and been doing it for 30 years now fulltime
I use old lime for my scratch coat when plastering. Never had a problem. People think too much nowadays. Lime's meant to be simple. Keep up the good work bruv.
Love your videos such an interesting subject and so much to learn. Inspired me to book some courses. Keep up the great work.
Where did you do the courses Ben?
I’ve not actually been yet due to the covid situation but I am planning on doing some courses at the Scottish trust lime centre in fife:
Thanks for the great video. How does a hot mix like yours compare in durability to a mix made of high-calcium content aged lime putty that in its putty form has matured for a few years? I guess a follow up question is when would one chose a hot lime mix compared to a traditional aged lime mix?
I think that first of all you'd need to cite your evidence concerning your claim about aged lime putty being used for pointing. Current research suggests that lime putty was only ever used for top coat plastering. It's now argued that pointing with it was an 80s revival thing - same as NHL. Mortar analysis over the last few years now provides evidence that only quicklime was used for building and pointing. Laying up putty for many months (or even years) only to be used for pointing would appear to be an expensive and unnecessary errand.
@@michaeljamesdesign , Hi Michael, my apologies. I am coming at this from the very narrow perspective of a fresco painter who uses lime plaster as a top coat, upon which I paint. I enjoy watching videos like these as they help improve my general knowledge about lime plaster. I didn't intend my comment to be about pointing, just the comparison of hot lime vs aged lime in general. In hindsight, I realize the applications (pointing and fresco plastering) are likely too different for that to have been a reasonable question.
Hi Mike, great video. Love the original pencilling. Would you put that back? I'm on a bit of mission working with Tim Meek and Nigel Copsey to restore and learn about old finishes. Just 1 little bit, I heard you say about spraying up. Don't over spray. Maybe the next day then maybe a week later. Quick lime doesn't need the spraying like putty does. Everytime you spray you re-slake. We're all in this together 👍
I don't over spray. This mortar has gone past the case hardening stage and is carbonating. So the lime can't re-slake. The mortar is subject to cold and drying winds and has some propensity to cracking. Another variable in the curing process is the amount of limestone dust in the mix. This has a pozzolanic affect which means it's prone to swifter drying. As I'm sure you're aware, carbonation, drying and relative humidity are all related.
I didn't realise it was you!!!
Have you ever considered penning a book? I believe that the wealth of knowledge you possess, coupled with years of experience, deserves to be immortalized - be it engraved in stone or eloquently expressed on paper.
Thanks Stan. Yes I have. I started it but never got beyond that. I also considered a series of DVDs but they went the same way. I'm currently experimenting with insulating lime renders so will post something on them soon. If you're looking for a good read then I can certainly recommend Nigel Copsey's.
@@michaeljamesdesign Michael, your content is truly appreciated. There's a resonance with what Peter Ward presents on his channel, even though he's been on a hiatus from new posts. However, you actively implement and embody the principles he shares in his videos, serving as living proof of their effectiveness.
Thanks
With portland cement mortar you can block 4 walls , 4’ high ,parge it ,fill it with water for a pool .
I wonder if you did the same with lime mortar how long water would take to drain through compared to Portland cement parged pool ?
Dunno, don't fancy finding out either.
😂 , I built a garage foundation wall once , on clay , 4’ high concrete block wall with Portland cement mortar . The thing filled up like a pool after a storm .water tight I kid you not .
Hi , rather then buying 3.5 nhl premix lime mortar , can you recommend what you use , I notice big bags of white Rhino lime at large builder providers .
Thanks
You can but you have to use it fresh out of the factory gates.
You say here if you are repointing old lime mortar use a quick lime. Do you mean repointing these sorts of stone buildings or do you include brick buildings too.
I always use quicklime for stone as that's what was originally used. However, I rarely use it on brick as the faces are usually porous so it stains and looks bad. It has to look nice as well as being sympathetic. I'd have no issue with it on the type of brickwork which doesn't stain. For me its putty or NHL or brick.
@@michaeljamesdesign Thanks
Hi Mike, did you add a pozzolan to your morter mix?
Yes.
Mike, I have been trying to learn about limes and there uses but in the USA it is hard to find anything other than hydrated lime. My question is about free lime content that you reference. Can you explain what that is, searches do not give a good explanation and usually reference concrete. I do learn a lot from your videos any really appreciate the time you spend making them. Thanks
All limes have an available lime content. Quicklime CL90 has the highest with 90% whereas NHLs have the lowest. Compressive strength is related to the amount of free lime. This gets burnt off the longer lime it's burnt in the kiln so an NHL5 has the lowest. If you keep burning you get cement. Free lime also contributes to workability. Good workability means it takes less time to apply. So high free lime is a winner all round. When you add pozzolan you reduce the amount of free lime because pozzolan eats lime. So if you want a hard lime for exposed sites then you add pozzolan. But this is a whole other science.
Joseph, US Heritage in Chicago, IL sells conservation-grade lime products. They sell hot lime (calcium oxide) and aged lime putty (calcium hydroxide).
I like the quick lime motar mix. Whats the make u use for quicklime and brand? Is it 1 part quick lime to 2 part plastering sand and 2 sharp sand? Why do ppl not use builders sand its like fine softer sand? Can i put sythentic as hair its hygenic?
Hi, thanks for the enquiry. There are a number of quicklimes available; the ones I use or job site specific. You'll be fine with your own recommendations for sand but again choice is as per job site. You can use building sand but it's pretty disgusting stuff. It doesn't matter when it's used with cement as this will lock in all the horrible stuff. Now do tell me, why would you desire to include man made hair in lime mortar?
I own a 17th century building here in Ireland , which I an rebuilding. The advice on lime pointing is varied and in some cases even involved cement. At the moment I am using a 3.5 Roundtower lime mixed with a portion of hydrated White Rhino lime and a plasters sand. Foe the interior. Getting a lovely workable mix. Any thoughts in case I am causing problems.
There's only one thing I'd mention and that is that Roundtower NHL 3.5 has a very low free lime content. It's only 18%. That's 82% impurities. Which is a lot. Their NHL5 contain more free lime at 25%. Personally I'd never use Roundtower NHL3.5 as it contains such a small amount of lime. Imagine eating a chicken sandwhich which only contains 18% chicken. Could you even call it chicken?
You don't specify what a portion is. You may be including too much or too little. Be careful. Gauge at your peril.
Thank you for such a quick reply. I am using a 1 -2.5 mix, but I did feel the result felt a bit hard. So I added 30% mix of hydrated lime to the lime mix. So 1/3 White Rhino 2/3 Roundtower. The mix felt really nice and has dried really well. I am taking the idea of the walls breathing very seriously and have been experimenting on small portions to get a good balance, over the past few months. Even the plastering afterwards , I will take my time, get a proper breathable mix. Thanks again for your reply, really delighted.
@@Jeremy64444 1:2.5 means you'll have more free lime but a higher compressive strength. Mixing in that much non-hydraulic lime might feel right but it doesn't necessarily mean to say that it is right. You may as well go all the way and use 100% fresh lime hydrate with a pozzolan. Personally I never mix in more than 10% - 15% non-hydraulic into my NHLs. So that means no more than 10% putty with NHL and no more than 15% lime hydrate with NHL. I never mix NHL and quicklime which is ffectively what you're doing. I take the concept of carbonation seriously. You're dealing with delicate setting processes and unless you have the backing of scientific research then you need to be careful otherwise your mixes could fail. Speaking of scientific research: there is evidence that mixing NHL and non-hydraulic lime results in the carbonation process can be slowed down dramatically. This translates to your mortar remaining vulnerable for longer. Do bear in mind that these results are born out of optimum lab conditions and these are rare in the real world. Remember, you are not a chemist.
@@michaeljamesdesign thank you, I always take advice, no damage done, as I have experimented on different small areas, will kook for a different product.
Again thank you.
Hi, thanks for your vids! What do you think about nhl5 full facing harsh weather and sun any advice? The wall I’m doing is also 1700 but the pointing was done 6 yrs ago and is pouring out of the pointing crevice! Followed all your vids and feel your experience is really sound! 10 miles from your Aston cottage job! Was your South Cerney sand mix from Collimoore pit?
If recently applied mortar is coming out then the problem lies in the mortar. What type was used?
@@michaeljamesdesign Thank you heaps for your reply! I can bring you a few pics and some mortar from the wall next time I see you out and about! If that’s ok! I have no idea what the builders used but it’s very fragile!
It sounds very like your builders used lime hydrate. This is very good when fresh and makes wonderfully rich lime pointing or plastering mortar. However, when it's been sitting around in the bag for a while it eventually becomes inert and is only useful as a plasticiser. Hence this isn't the first time I've heard of lime hydrate mortar failing. If you want to use NHL then I'd recommend 3.5 for an exposed and weather-prone situation. Mix it 1:2.5. Just don't use Secil. I can't give you details of the sand or the blends I use. Trade secret and all that. Just don't use ordinary builder's sand.
Synthetic hair replacement = fibreglass based plastic flake stuff. You heard of/tried it yet?
No and I won't try it either. No need when I have stables next door.
Hi Mike, Can you tell me how much hair one should put in the mortar for pointing?
For quicklime?
Hi Michael , can you mix crushed lime stone 6mm grit down with hot lime ? Because I’m Finding it hard to get washed sharp sand with a grit in it .
Tnx mike
Of course you can Michael. But be aware that your crushed stone will be 6mm down to dust and because of the fines it could take longer to dry out which could cause problems when it freezes if there's still a moisture content.
@@michaeljamesdesign thanks 🙏
@@rosslukeshay My pleasure. Good luck.
im tempted to try do a limecrete floor with hot lime
Oh.
@@michaeljamesdesign i cant see any reason it wouldnt work can you
How long does lime mortar typically take to cure/set mate?
That depends on a number of variables and is quite an expansive question. It also depends on your definition of cure.
It’s a Penny roll joint is that.
It would have to be a wide penny. Penny roll tends to be on brickwork. On stone it's (traditionally) called pencilling. But what's in a name. I'm not going to lose sleep over it. But then again.....
@@michaeljamesdesign maybe…that’s where a rolling stone gathers no moss comes from?
Ooh
Yes.