Making Lime Mortar (hot mix) Tutorial

In this video I shall be explaining how to hotmix quick lime and sand using a force action mixer
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[@davidp8563]

Out standing instructional vid.....exactly what I have been looking for. Thank you for sharing your knowledge and experience.

[@matthemason7918]

Hi David I try and answer all sensible questions on here. You can also find me on Instagram @1matthemason I'm super glad it's helpful, all the best Mat.

[@mainstreampropaganda7518]

well brought together and has filled in educationally many floating questions i had! thank you!

[@perthbrickrepair1392]

Best demo I ever watched. Thankyou for the lesson

[@rossfletcher4362]

Thanks Mat, great info.

[@florentinalily]

Fascinating; thankyou Mat. The horsehair that they used to use was from the mane and tail as it has the long staple .. usually from the knackers yard. Just in case anyone is thinking of using the hair they have brushed their horse with.. Love the mixer.. just going to google it now! Thanks again x

[@richardgrimbleby7853]

Goat hair was just as commonly used

[@florentinalily]

@@richardgrimbleby7853 yep; I suppose it depends what access you had to each animal.

[@richardgrimbleby7853]

@@florentinalily hi it's not commonly known but goat hair was sometimes used it is a little coarser thanks for your reply

[@matthemason7918]

Well the main and tail are really good for render/plaster work but it's not the best for repointing brick and stone work. If you know anyone with blond hair that is getting cut I can personally say it works very well in the mix and stops the pointing from cracking although you still need to keep the joints damp for over a week.

[@matthemason7918]

​@@richardgrimbleby7853all well nearly all hair can be used the whiter the better and straight is better than curly

[@Bernieclark45]

Excellent video, well done.

[@TheJosepi87]

nice vid mate cheers, im only just finding out about hot limes, been using NHL's for ages but starting to find out that they are not all that and hot mixes are the way to go, something to do with the free lime content apparantely 🤷‍♂️anyway cheers for the vid

[@stihl3826]

How long would you wait between mixing hot and deep pointing a rubble stone wall?

[@DRJMF1]

Very nice demonstration. What mixture would you use for lime plastering drywall brickwork, its an 1890s cottage with lime pointing ? Would it be applied hot, direct from your Baron mixer with horse hair ? Is roller pan mixer better than a Baron mixer, if so, which roller pan mixer is reliable ?

[@matthemason7918]

To be perfectly honest I'm not an expert on solid lime plaster in other words I've given it a go and it's hard work as the more you fiddle around with it the more cracks appear as it cures. I have used it still hot with hair in it but that's for sacrificial lime vendors to prevent further salt damage lower down on the outside of buildings. Forced action and pan roller are two names for the same thing sorry I couldn't be more help.

[@ianb9103]

Great video. Hopefully will see more in the future👍👍

[@matthemason7918]

Maybe I did this for a friend so that it could be used as a training video. Is there anything you would like explaining or showing best practice how to do if you have any questions I'm happy to help.

[@ianb9103]

@@matthemason7918 its good to see traditional methods and good explanation. I really enjoy great content vids. Hopefully will be repointing our 200year old community pub very soon. Also reslating the roof. Interesting times ahead for us volunteers.

[@matthemason7918]

Give me a follow on Instagram at 1matthemason I've got many other examples of my work and why I'm doing it the way I am. Hope it helps and good luck with the repointing and slating. I always say fix the roofs and gutters first then the sky surfaces and then the pointing.

[@tommyb5244]

I think my house is lime plastered originally because the walls don’t have insulation in them. Do you think it’s a good idea to knock all plaster off and batten with insulation board? Or knock it off and re plaster with lime mortar

[@matthemason7918]

My advice is that the building should be using the original style building materials and not to change it as this can cause problems with air flow and mould. If you start to use modern materials in old buildings then locking in moisture is a real problem, old buildings need to breathe. Sorry I can't be more specific but remember you are the custodian of that property one of many that has been and if you treat the building with care many more after you.

[@avfczoff]

Great video and good insight into what goes on. Do you need to keep the mix going until it’s cooled down before you put into buckets? Is it literally a case of breaking the mortar up out of a bucket after being stored away and tipping into new bucket and mixing again? Is it best to let the mix cool before pointing regular brickwork or do when still hot? Sorry for all the questions! Just came across your video and value your opinion. Also do you have a link for the sand you use? Many thanks

[@matthemason7918]

Hi villa first things first the sand I use is from Tasmania maybe a tad far for you to order. A good tip is to rub sand between your fingers and if they are mucky and the sand gives a smudge stain then the sand has silt and clay in and is no good. Sand needs to be well graded you could try and google rose of Jericho for sand. Don't point anything when it's still hot as it is still expanding and will blister. As long as the bucket isn't going to melt you can take it out any time but be wear it hurts if it gets on your skin. And finally yes it does go hard in the bucket over many months/years just dig it out and knock it up with a paddle mixer. Hope that helps

[@avfczoff]

@@matthemason7918Hi, really appreciate your help and I’m very grateful! Best wishes for the future Villa!

[@matthemason7918]

@@avfczoff up the manor

[@tomtom4633]

Just found your channel, great content! At work we use nhl 3.5 2 parts, 2 parts plastering (brown sand), 1 part yellow sand, 1 part Sharpe sand. It does seem to sag and crack, is this the wrong type of sand to use, what would you advise for ratios using nhl 3.5 lime. We have never tried hot mix lime but I'd love to have a go with it.

[@matthemason7918]

NHL doesn’t have the stick ability with a mature lime mortar made from quicklime that was slacked with the sand in other words if I tip my trowel upside down the mortar stays on it. Hope that helps

[@plummetplum]

I'm currently using NHL with sand and rabbit skin glue for pointing. Question is, can i store this mixture indefinitely in an air tight container? Also how is lime mortar from quicklime different to lime mortar from NHL? Is there a reason why you would choose one over the other?

[@matthemason7918]

Natural hydrologic lime sets and will set under water for most sedimentary stone is too hard. Quicklime hardens by absorbing co2 and there isn't any of that under water. I have never heard hind nor hare of rabbit glue!

[@MusicComposerZenki]

do u happen to know anything about this mixture together with rice soup which they used for the great wall of china? if so, please inform me

[@matthemason7918]

Hi shpendi rice water is mostly starch so I'm led to believe which will harden when the air comes into contact. I'm rapidly getting out of my comfort zone so I think I best leave it there.

[@gary24752]

What sand is it that has the dark sharp flecks that show up once the joint is hit with the chum brush to compact the joint?

[@matthemason7918]

Sands are different all over so if I were you I'd take a look at your local builders/landscape yard and see for yourself. Where are you?

[@gary24752]

@@matthemason7918 Why are some videos of joint replacement showing white mortar in sharp contrast with what is existing?

[@matthemason7918]

@@gary24752 because lime is white the colour comes from the sand. You can use an oxide or leave it for the years of time to tone it down.

[@amyntas97jones29]

When it's in a bucket do you have to put water over the top?

[@matthemason7918]

Officially the answer is yes but as long as the bucket has an airtight lid then it will be totally fine as it only carbonates because of CO2 (goes off) in the air.

[@ccbilsky]

What if you want to use it the next day or at most in a week? Any advice?

[@matthemason7918]

You can use it straight away but it’s easier to use and better to be matured.

[@GMTpointingspecialistsltd]

I use my hot lime after its cooled down So it's fresh When you said you can keep in for a long time or people say it's better to keep it for a year It's not a hot lime it becomes more like a putty

[@matthemason7918]

The term hot lime is a little miss leading here in Australia they call both crisps and chips "chips" and distinguish between the two by calling one hot chips and the other cold chips. It gets very confusing when hot chips go cold, they become cold hot chips. This is the same as hot mixing lime. Fixing while the lime is still hot or most likely a little bit warm is totally different from when the mortar has had time to slake in a bucket but both have been hot mixed. What I'm trying to say is that it's the process that gives it its name. Most of the time when I'm fixing I use putty as it's cheeper but they are different. (I hope that makes sense!)

[@GMTpointingspecialistsltd]

@@matthemason7918 now I want fish and chips lol thank you

[@florentinalily]

can you use a conventional concrete mixer to mix?

[@matthemason7918]

Yes But if you're hot mixing it is very dangerous as it will spit hot lime at whatever it is facing and what I've told it is best to put large stones of bricks in it so that the lime and sand are mixed correctly.

[@NicolasTheondine]

Hello, for a better workability of your mortar you can try this. - 1 volume lime putty (home made) - 1 volume fine "pouzzolanic" material (easy available with "Metakaolin" 1000) - 2 volume of coarse sand. Mix them together, with a small quantity of water. Then add 1 volume of Quick lime and the just amount of water to slake it. The result is a plastic sticky mortar which become gently strong within just a day (in winter), far quickly stronger than our common lime mortars (well even if "strong" or "hard" is maybe excessive for a lime mortar) ;-) (It's a recipe described since mid XVIII in France, maybe earlier elsewhere)

[@matthemason7918]

Hi mate you've turned your airlime into an hydraulic lime. You can just mix up a small amount of sand and quick lime and use it when it's still hot for fixing but be careful it gets very hot and never grout with it as quicklime expands and will push walls apart. Not that I found out this the hard way🤔😉

[@StanOwden]

After saying that this recipe was used in France, I can’t help but ask if you have heard of outdoor rendering, which in France is called 100 year rendering or something like that. Commonly used for leveling farmhouse stone walls. They say that if the technology is followed correctly, it will last for a hundred years. I don’t know how true this statement is, but understanding that there can be more than enough nuances in the configuration of a lime mortar that can influence many factors, I wouldn’t be surprised if similar recipes exist.

[@NicolasTheondine]

@@StanOwden Never. Mainly because translation is difficult, I think(I'm sure). The normal way to protect a stone wall (bulk stones) was to cover it with a lime based plaster (un enduit a la chaux) and to renew it every 5 to 10 years with a milk-lime (un lait de chaux). And of course it can last a hundred years. The same way as everywhere. Was it the point of your question ? France may look very small, it is, but geological differences are wide, in less than 100 km you're in a different country. Technics and practices are like that. ;-)

[@ianm4]

Great video. Thanks for sharing. When you say quartz sand, do you mean silica sand?

[@matthemason7918]

More of an engineered sand ie. irregular shaped sand without the rounded grain of a beach or river sand.

[@gangadin2873]

@@matthemason7918 For cement, I hear some people really prefer the rounded grain of river sand - Is that sensible? Didn't make sense to me -but maybe I am missing something.

[@matthemason7918]

@@gangadin2873 the cement is the binder and the strength. Lime is the binder and the irregular shaped grains of the sand builds the lime mortars strength.

[@BMG6519]

@@matthemason7918 further detail - engineered sand is created by crushing rock. Can be from granite and quartzite most often and many other rock types depending on local geology. As a crushed material there will be all broken faces on the grains creating the irregular shapes. In addition the product will have a range of sized grains all the way down to dust. The combination of angular grains with a range of sizes means tight packing. This means the lime binder does not have to fill large gaps. River sands can often be missing size fractions resulting in poor packing. That combined with round edges means the grains can roll out resulting in poor strength.

[@matthemason7918]

@@BMG6519 yep you are spot on its the engineered and well graded sand that's best. It does however depend on the size of the joint where the bell curve will be big joints that you might see in rubble walling will need the bell curve to go towards the courser or larger particles end of the scale and vice versa if it's a 2 or 3mm joint the bell curve will need to move to the finer end. But I have a hunch that you'd be able to explain it far better than I.

[@JB-xo1bd]

Where do you get your engineered sand? Are there any UK national suppliers? Thx

[@matthemason7918]

I would ask about, hit the phone's see what your local diy, garden centre or landscapers have.

[@JB-xo1bd]

@@matthemason7918 I've done all that. They don't seem to have a clue what I'm asking for. Found a supplier in Cornwall, Cornish Lime, but huge palletised delivery cost.

[@matthemason7918]

@@JB-xo1bd that's no good what about limestone quarries they need limestone to burn to make quick lime.

[@grahamsmall1250]

Hi I’m about to repoint a garden wall ,I’ve ordered 2 bags of nhl 5 will it be ok to use for repointing I’ve heard 3.5 is better thanks

[@matthemason7918]

Is it a very wet area?

[@grahamsmall1250]

@@matthemason7918 not really,can I make it a bit weaker with more sand say 5 sand and 1 lime mix

[@matthemason7918]

@@grahamsmall1250 NHL 5 will have a set but if it's just for a garden wall then it's not like your house will be damaged. If you try and make it weaker by putting more sand in the mix it will be 🤮 to work with.

[@grahamsmall1250]

@@matthemason7918 I’m going to return it and get some 3.5 do you know of a good supplier

[@matthemason7918]

@@grahamsmall1250 I'm not sure where you live I can tell you where to buy 3.5 in Australia

[@Mrwesmrwes]

Thanks for the great video and explanation on lime mortar. That stone scraping between the paddle and the drum would drive me crazy though.

[@matthewcox4146]

Hi Mat, great video 👍. I am from Oxfordshire and trying to get into working with lime and stone work. Where did you do your apprenticeship? Do you have any companies you could recommend I get in contact with? Thanks Matt

[@matthemason7918]

Hi Matt I left Oxford in 1997 where in Oxfordshire are you as I've still got some contacts

[@matthewcox4146]

thanks for the reply. I'm near Banbury :).

[@matthemason7918]

@@matthewcox4146 my mum grow up in Banbury and I grow up in Hampton Poyle. I did my apprenticeship with a company called A.P.S. in Oxford. My advice would be to take a look at one of Facebook's groups called Stonemasons guild and ask on there I'm positive that they'll help you out all you need do is ask.

[@keithlittle293]

How do I get the white lime mortar colour???

[@matthemason7918]

What colour is the sand you're using? Lime will be white unless the sand has a strong influence or you put an oxide in it.

[@keithlittle293]

@@matthemason7918 I just want a white mortar like seen with the Victorian red imperial brick.. so whatever sand I would need for that???

[@matthemason7918]

It's hard to know for sure what you need without seeing it are you on Instagram?

[@matthemason7918]

Are you looking to do tuck pointing? Or brick replacement?

[@keithlittle293]

@@matthemason7918 both really.. maybe is better use normal stuff.. rake out and repoint with white Or lay and point with both ideally

[@bogey19018]

Is quick lime the same as NHL ?

[@matthemason7918]

In a word no Quick lime is what you get when you burn limestone or shells and turns into lime putty that is sometimes called a air lime this is because it draws CO2 from the air as it cures whereas NHL or natural hydraulic lime uses a chemical reaction to set.

[@bogey19018]

@@matthemason7918 Thanks mat. My name is matt, I'm also a mason. This is one area I never learned and was never taught. Seems like its mostly used for historic restorations.

[@matthemason7918]

@@bogey19018 alright Matt, yeah I was looking at my old college folders from 1990 and I was being taught about 12-3-1 mixes which are just a weak/crap cement mix. I'm happy to pass on my knowledge to those who want to know, give me a follow on Instagram @1matthemason I've got other posts up there and it's a little easier to answer your questions if you have any.

[@cameronduffy6979]

Mortar Chef

[@jamesnoone3556]

Matt, you need to get a better microphone. Great vid.

[@ironimp1]

Good video, however It's a shame that you did not put on a mask when introducing the quicklime as it is extremely dangerous if you breathe it in. Historically the lime makers died very young from respiratory problems. Gloves would have been good practice too. Just one other point; synthetic fibres do not degrade as you suggested, it is animal hair that degrades and there has been a lot of research done to establish this. Some animal hair is less prone to degradation and the percentage of hair to lime makes a difference too (heavily haired plaster lasts longer). Plant fibres such as hemp are a good alternative. I was very pleased to see you mix hot in a proper forced action mixer and did not use it hot! Storing hot lime for at least a few months (preferably a year or more) is, in my opinion the very best of all worlds. I hope to see more of your videos from you Mat.

[@matthemason7918]

Cheers mate lime won't kill you soon as look at you, it will on the other hand burn your lungs as it's very Alkaline so my advice is don't breath it in but saying that feel free to wear a mask as it's all personal choice. I've seen horse hair that's well over 200 years old in lime mortar outside on an old church and it's still doing a job. Man made fibres don't feel as good as they clump together and a pain in the backside. As for cloves if lime gets into the hands and you don't have hands like me it will eat into the skin. I keep my hands dry and at the end I wash them and most importantly moisturise after. I must make a point of both the concerns in the following video's if I ever get round to making any more.

[@gangadin2873]

@@matthemason7918 Will dog hair work the same? I reckon we can get heaps of those from dog groomers

[@Scribe3168]

@@gangadin2873 human hair from the hairdresser?

[@jauld360]

@@matthemason7918 He means that animal hair degrades in unset mortal, during storage.

[@wombatau]

Quicklime no mask. Kids don’t try that at home unless you’ve been doing it for a very long time.