How to mix Otterbein Naturkalk CL80

Mixing quicklime 1:4 CL80 in winter.

[@michaeljamesdesign]

I did say in the video that the ratio was 1.5:3 when it's actually 1.5:4. My apologies.

[@steveelkins6031]

I use Otterbein Branntkalk 80, quite a bit here in the U.S. I really enjoy using it. The slower reaction is definitely a benefit safety wise.

[@michaeljamesdesign]

Thanks for the comment Steve. Very much appreciated.

[@utrinqueparatus2344]

Just to wish you a Merry Christmas Michael 🌲

[@michaeljamesdesign]

Thank you sir. And to you too.

[@MrDziuka]

Thank you.

[@Southpoint2019]

Great info Michael

[@michaeljamesdesign]

My pleasure Sir.

[@edinburghwheatgrass8106]

Hi there, I have just been mixing otterbein cl80 as well, here up north in the Scottish Highlands. I and was checking to see if I'm doing ok. We used builders sand and added a bit of top soil to 'get clay content'. Something I read. Not sure if that's what will work, but so far the chimney on the derelict structure looks amazing. Would you please advise what aggregate/sand and in what proportion regards the lime and water.

[@michaeljamesdesign]

1:2, 1:3 or 1:4 depending on the circumstances and vernacular. I couldn't advise on topsoil though. We never use it. The only thing we do is, occasionally, use a sand with a pozzolanic clay content but that is very prone to cracking.

[@edinburghwheatgrass8106]

Thanks! Back on it again, theres no cracks but I'll stay away from the topsoil now

[@DRJMF1]

Thank you, very generous of you to share your method of dealing with as slake transition reaction. Is your volume gauge ratio of quick lime : sand : water at 1:3:2 ? Willl this mixture be good enough for plastering directly onto the wall, in a hot condition, or will the evaporation of water be too high causing cracking ? Can you store that CL80 mixture inside a sealed bucket and then knock it back up by e.g. beating with a stick, or a squatting it in a roller pan mixer to make a good plaster that don't shrink/crack too much ?

[@michaeljamesdesign]

Respectively: no, probably, maybe, possibly, no.

[@peterridding4874]

Hi Mike happy new year and thanks for another informative/ invaluable video . One quick question please , in another of your videos titled “ hot mix lime “ you seemed to fairly drench your mix initially to get it slaking whereas in this video it’s a slow steady water addition to enable the slake ? Both hot limes but two different methods. Sorry for my ignorance, I’m trying to get a handle on hot lime work. Many thanks

[@michaeljamesdesign]

Yep, all limes are different. Each one needs a different approach. To quote Swiss Tony from the Fast Show: making lime mortar is rather like making love to a beautiful woman....

[@gartenfreude796]

Your channel is sooo interesting to me, as a beginner. Very informative. Actually I live in the northern part of Germany and Otterbein is about 150km away from our city. If I assume correctly you do use CL 80-Q. Is quicklime only used in winter or do you use quicklime for certain purposes?

[@michaeljamesdesign]

Hallo Gartenfreude, I use it all year round for pointing.

[@gartenfreude796]

@@michaeljamesdesign Thanks for taking the time to answer. May I ask another question, why or when you use quicklime? I have assumed that you also use NHL for pointing and wonder how you decide to use one or the other.

[@michaeljamesdesign]

@@gartenfreude796 I've given up with NHL. Can't see the point in it if I'm honest. I only use quicklime now. I use in all year round.

[@gartenfreude796]

@@michaeljamesdesign Thanks for sharing your insight and experience.

[@michaeljamesdesign]

@@gartenfreude796 You're most welcome sir.

[@matte999me]

Thanks for the video Michael. A couple of questions if you don't mind! Who first put you onto the CL 80 and took you away from using the CL90? Also how do you change the characteristics of the mortar for different use like you can with the pure air lime with pozzolanic addition as you mention not adding anything at all to the CL80. Keep up the good work and merry Xmas 🎅🎄

[@michaeljamesdesign]

Hi Matte, nobody put me onto CL80. I just fancied it. I still use CL90, NHLs and putty. I don't understand the question about changing the characteristics of the mortar for different use. Try rephrasing it.

[@matte999me]

@@michaeljamesdesign sorry characteristics as in its hydraulicity (if that's even a word!) For example mortar for a roof ridge. A mortar for a highly weathered gable, mortar for a softer stone or brick. So with a cl90 you can change the mortar for its purpose by adding mote/less pozzalan. But your cl80 that you use as is. Will this only suit a limited function in where it is used. Sorry a lot of words to try and explain my point!!

[@michaeljamesdesign]

@@matte999me The CL80 isn't a hydraulic mortar but it does act like one because of the impurities. It's a quicklime and needs to be treated as one. It's just like CL90 but with additions which help it set more quickly. But if you want to increase strength then you just add a pozzolan. I often add wood ash but that reduces the free lime content down a little further to something like a CL70.

[@stihl3826]

Hi, if a bag has been opened can it go off and how will you know if it has done so ? Will it refuse to slake ?

[@michaeljamesdesign]

It'll be inert - won't slake. But you can still use it as a plasticiser for NHL.

[@ironimp1]

Thanks for the video. I think the addition of straw in to the hot mix will work well, but putting the horse hair in so early on in the slaking process will attack the keratin in the hair. Is it possible to add the hair at a later stage?

[@michaeljamesdesign]

Hot mixed mortar is applied straight away i.e. whilst still hot - for a number of reasons. The only reason the horsehair is there (alongside a number of other ingredients) is to help reduce initial shrinkage.

[@michaeljamesdesign]

In another video I'll try and remember to say something about the horsehair in the original quicklime mortar still being present as a binder.

[@ironimp1]

@@michaeljamesdesign That makes sense. Thanks.

[@michaeljamesdesign]

@@ironimp1No worries. It's important that people realise that the ingredients which go into a traditional mortar or plaster go in for a reason. There's no flight of fancy involved. It's also important that we know the reason for adding what we add at a particular time during the mixing process. Quicklime mortars have all of the ingredients added at the same time. It's all about conservatorship. As the original masons from the 16 and 1700s used a lot of horsehair in their quicklime pointing and plastering mortars then we have to know why they did it and at what point so that we can achieve a similar outcome.

[@ironimp1]

@@michaeljamesdesign Agreed, I recall the tanners using quick lime to dehair the skins, so as you correctly pointed out, the hair that you include early on will dissolve, but not before it does it job of preventing the initial shrinkage. I also note that you use local horse hair which, along with pig hair, I have found to be more resistant to the alkali attack. Plant fibres are excellent as they seem to improve in the presence of lime, so your straw addition would act as a reinforcement after the lime has cured. I know that some research has been carried out in this area, but as always, it would be good to know more.

[@DRJMF1]

What is the manufacturer name of the paddle mixer ? What is the shape of the paddles e.g. rectangular and of a dimension comparable to the volume of the rubber bucket for efficiency mixing right ?

[@michaeljamesdesign]

Respectively: can't remember, round, don't know.

[@TheJosepi87]

Hi Michael, what would be the benefit of using the mortar hot straight away rather than the same mix cold the next day? cheers Joe

[@michaeljamesdesign]

There're arguments for and against. I only use it hot during the cold weather if that's any help.

[@michaeljamesdesign]

There are many. And I'm not going into them here. But if you want to know more then read Nigel Copsey's book on hot mixed mortars.

[@TheJosepi87]

@@michaeljamesdesign cheers Micheal yes I have come across his work, he seems like the real deal, thanks for your reply

[@michaeljamesdesign]

@@TheJosepi87 He is. And he has a preference for hot in winter. We only use small volume mixes when it's cold.

[@stihl3826]

If slower to slake does it make it safer?

[@michaeljamesdesign]

That's an interesting point. I'd say probably yes. The heat build up is a lot slower and I never bother with goggles or a respirator with this one. With Calbux they're both an absolute requirement.