Using Lime?

[purplemonkey]

hi,

I've read a ton of stuff on this new fangled Lime business, but it just leaves my head spinning. I can see why people stick to cement!

so here's my scenario, I bought a 25kg bag of NHL 3.5 and a tub of Lime putty. Thought I'd try them both out.

my questions, how do I mix them up.

the bag of dry nhl 3.5
1. I put a shovel of it into a bucket
2. added little water and mixed till it was a ball of putty
3. then I added 2 and a bit shovels of sharp sand to it, mixed it up, and it looked pretty good as a mortar.
4. I've put one brick down with it and will let it dry out and have a look.

Does that sound like the right way to do it? I keep reading bits of info saying you should mix the lime/water and leave for 24 hours....

If that sounds right I'm going to assuming the lime putty will just put me at stage 3 straight away?

 

[seasickstevie]

... this new fangled Lime business ...

nothing like moving with the times ...

 

[ree]

Why not transfer your post to the old fangled plastering forum?

 

[purplemonkey]

Why not transfer your post to the old fangled plastering forum?

cause its not really plastering, its building init.

I'm making mortar, sorry if that wasn't clear in the original post.

 

[stuart45]

NHL gets 20 minutes in the mixer, left for 20 to fatten up, then mixed again for a few minutes.

 

[RogueHanger]

If my memory serves me correctly, lime putty and NHL (2.0, 3.5 & 5) lime set differently.
Lime putty cures by reaction with Carbon Dioxide. Whereas NHL lime cures by reaction with water.

You'd use lime putty for lime wash and where feeble lime would be OK, e.g. intenal plaster, etc. You can use it for mortar, but be prepared for a long curing process and protection while it cures.

NHL lime can be used almost like cement with a sharp sand. It's not suitable with a soft sand. (the pores of the mortar are reduced if using soft sand, thereby reducing the breathability of the mortar.)

You can use a NHL 2 for plaster (internal) and mortar for brickwork.
In more exposed locations it would be better to use a NHL 3.5 or a 5.
NHL limes cure quicker than lime putty used in plaster or mortar.

I've used a 3.5 and a 2 for internal plaster, and a 2 for limewash, no problems.

Edit: just found this which might help.
http://www.lime-mortars.co.uk/articles/lime-hydraulic-or-non-hydraulic

 

[ree]

Interesting information by RogueHanger.

OP, stay away from lime putty unless you have been mentored in its mix and use. It will burn and irritate on skin. We only used it for specialty purposes eg. running cornice/coving repairs etc.

A typical Lime mortar mix for me would be 3 sand to 1 lime. Just ask at a Builder's supplies for bagged lime, tell them what you want it for. We would use whatever sand was available - no call backs.

 

[purplemonkey]

Interesting information by RogueHanger.

OP, stay away from lime putty unless you have been mentored in its mix and use. It will burn and irritate on skin. We only used it for specialty purposes eg. running cornice/coving repairs etc.

A typical Lime mortar mix for me would be 3 sand to 1 lime. Just ask at a Builder's supplies for bagged lime, tell them what you want it for. We would use whatever sand was available - no call backs.

thanks for your views, yesterdays test brick set nice and hard so today I have been using 3 to 1 mix all day.

a quick question, does it matter if you mix lime/water or lime/sand fist?

and what if you don't mix for 20mins?

From what I've made so far, I'm actually preferring it to cement, well apart from its lack of stickiness. It doesn't appear to want to stick to the end of a brick. So any advice here would be appreciated?

 

[stuart45]

If using NHL mix the lime and sand together in the mixer for a few minutes first. Dont add too much water to begin with as it will get wetter as it mixes.
Most people use 50/50 sharp/building sand to make the mortar easier to work with.
It needs longer than cement in the mixer.

 

[ree]

"3 to 1 mix" of what?

Always add powder to water.

But: Always mix sand and lime or sand and cement etc. first, and then add water.

 

[stuart45]

and what if you don't mix for 20mins?

Sorry, didn't answer that question.
If you only mix it for a few minutes you will have to put excess water in to make it workable, which will weaken the mix and cause more shrinkage. The mix needs time to take in enough air.

 

[RogueHanger]

The only thing that I would add is that if you just use "bagged lime" i.e "hydrated lime" from a BM, you may not know whether it's hydraulic or non-hydraulic.
As this link shows, bagged lime can be either.
http://www.lime-green.co.uk/knowledgebase/Hydraulic or hydrated Lime

I have used a hydrated bagged (non-hydraulic) lime for internal plaster, and it performed better than a hydraulic lime (NHL2). The main difference was the time to cure/work the plaster.
Non-hydraulic lime plaster could still be easily polished the next day, possibly even after two days, whereas hydraulic lime plaster could not.
IIRC, the non-hydraulic lime plaster needed about a week before curing properly.

I guess similar would hold true for lime mortar. Thus non-hydraulic lime mortar would need protection for a few days and the amount of work possible would be limited by the slower curing process.

 

[purplemonkey]

The only thing that I would add is that if you just use "bagged lime" i.e "hydrated lime" from a BM, you may not know whether it's hydraulic or non-hydraulic.
As this link shows, bagged lime can be either.
.

Buying Lime is terribly complex, I think they should rename the two to stop all this confusing, and probably simply the overall terminology! I reckon this complex information side will keep people away from using it. For example I've never heard anyone tell me how they make cement, but everyone seems to have to tell you about how lime is makes i.e lime slaking, burning etc... seems a bit OTT

Anyway B&Q only sell Hydrated lime, which I believe you have to mix with cement. So that seems pointless in the whole using Lime argument.

Very few Builders merchants sell Natural Hydraulic Lime easily recognized as NHL 2, 2.5 or 5. and where 3.5 is the most common.


My understanding of the Using Lime argument:
1. Consumes CO2 verses Cement which creates CO2.
2. Can easily be removed from bricks on demo work, verses cement which generally requires landfill of all materials.
3. Excess mortar/render can be stored for longer and more likely to be used, cement goes off and has to be land filled. (I've not seen this one first had as yet)
4. Lime mortar allows movement, cement will crack if any movement.
5. Lime allows moisture through itself, cement will block. This apparently causes brick spalling.

As someone who recycles and respects the planet more then my forefathers (not their fault, I mean who knew!), Lime is easily the material of my future. Just wish I knew how to use it