Advice needed on repointing.

[charlie-ia]

thats really helpful thanks!
we only made a tiny amount, but were adding dry powder to a dry bucket and trying to mix it immediately, so you can imagine what a mess we've been making!

 

[MdB]

My method is simply what I have found to work best. Others will have their own ways (which may be better).

 

[NT]

I've not tried this one, but it sounds sensible:

Stand lime bag upright on a small sheet of wood
Slash top open
put upside down bin on it
turn the whole lot the other way up
Let dust settle before removing sheet lid, removing bag & adding water

 

[Lady_Mari]

The other half has been mixing up small amounts most evenings this week for pointing, he puts a shovelful of lime in a bucket, then 3 shovelfuls of sharp sand, then mixes this for a good 5 mins before adding water.
He uses approx 40 lts water to 25kg & it ends up the consistency of thick dbl cream.

 

[MdB]

The other half has been mixing up small amounts most evenings this week for pointing, he puts a shovelful of lime in a bucket, then 3 shovelfuls of sharp sand, then mixes this for a good 5 mins before adding water.
He uses approx 40 lts water to 25kg & it ends up the consistency of thick dbl cream.

That will produce a lot of dust that way. Lime in your lungs is not something that it recommended.

 

[charlie-ia]

can you leave it after adding the sand? i was under the impression that you had to use it straight away if it was mixed like that?

 

[MdB]

Hydrated lime + water + most types of stuff will keep for years as long as it is kept wet (ie, with a layer of water on top).

Hydrated lime + water + (pozzolan or brick dust or other fired clay ground up) will set whilst wet so can't be stored.

Hydraulic lime + water + any stuff will set whilst wet so can't be stored.

I have a tub of lime mortar in a tub which I will knock back up (mix well) and use this weeked even though it has been there for 6 months or so.

 

[Gervase]

A paddle mixer is a boon. If you've got an electric drill of 750 watts or above, you can pick up a paddle for under a tenner that will fit into a standard 13mm chuck that will make the mixing of your lime and water a lot easier. It's indispensible for limewash.
If you have more than 1000 watts, you can even use the paddle for mixing mortar and plaster. Or, better still, if you've got a lot of plaster or render to mix, and don't want to use a bell mixer, a purpose-made mixer like this is ideal.

 

[charlie-ia]

is a cement mixer not good for mixing lime then?

 

[Gervase]

Yer bog-standard Orange Belle mixer is pants, I'm afraid. Ideally you need a pan or roller mixer, like the Baron or Rolapanit, but if you use a drum mixer you're better off with one on which you can adjust the angle of the drum, like the bargain Clarke mixer from Machinemart. The drum on the Belle is at too high an angle, and results in mixes balling if you use powdered lime and sticking to the back if you use putty.
You can remedy the problem by wedging a baulk of timber under the rear leg/s of the mixer, but one with an adjustable drum is much better.
Or, for smaller quantities, a paddle mixer is champion, and will take up a lot less room. I've just been rendering a house today, and the Freud paddle mixer was ideal (though I'm less than enamoured of your bog-standard render sprayers - six seconds for each fill is back-breaking work, particularly when it takes a compressor the size of a Ford Ka to run it! Why will no-one west of Oxford hire out a proper machine?).

 

[charlie-ia]

blimey! and there was me thinking how good my teaspoon was for applying the mortar!

 

[MDE]

I may be a bit simple, but I find the best way of making lime mortar is to mix hydrated lime powder with sharp sand (horticultural, not standard builders merchants') as a dry mix until it is all evenly mixed and no white bits left. I do it outside in a wheelbarrow, with a dust mask on. Then I add water and put it into plastic buckets, seal and mature for a couple of weeks. Cheap, easy, and just as good as any I've bought or made with putty.

 

[vannie]

Wow, such a response thanks. Sorry not to have replied sooner but have been on holiday, the builder is coming round at the end of the week to look at the work so I shall furnish him with all your advice. One other question our house is a semi and the back wall does not need doing so we are talking side and front, as a ball park figure any ideas as to what might be a reasonable price ( we are in Southampton) ??
Thanks again Vanessa

 

[michael]

I’ve been trying to understand lime for the past three years and everybody on this website will tell you to use hydrated lime (non- hydraulic) whatever you're doing. however a few months ago I employed a company of lime plasterers to do some internal lime and horse hair plastering (using hydrated lime putty of course) The company comprised of a guy more than seventy years old who had been plastering with lime all his life, he even had a gap in his teeth where he held the nails in his mouth for fixing laths, apparently dipping each nail in linseed oil before hammering in.(this was prior to the invention of stainless steel nails) The other guy was his forty + year old son who is now the boss and his son who was the labourer. The point of all this is that this long standing family business, who have been plastering throughout the generations had one simple rule. Use hydrated lime inside and hydraulic lime outside.

 

[Nemesis]

Hydrated lime is indeed non-hydraulic.

So is ready mixed lime putty, but it's rather more expensive. Some people think it makes a better, more workable mix, but many are now experimenting with hydrate (which is rather more readily available, which is useful) and finding good results.

Some of the problems of the stuff carbonating in the bag and therefore not being of any use are being overcome by plastic lined bags. Alwys use it fresh though.

On a personal basis, I would use non-hydraulic for inside and out, as first choice, but appreciate that there are times when hydraulic is a better choice.

Limes in times past were variable, and depended on local variation too. Some were naturally weakly hydraulic.

However, simply because people have been doing something for years doesn't make it always the right thing to do.

Did they say how hydraulic, and give any reson for why they always use hydraulic externally, other than because that's what they always do?

I can see advantages for tradespeople - it's easier to have something which sets chemically rather than by carbonation, as non hydraulic putty does, and possibly needs less management.

 

[michael]

The company referred to above, and myself, are based on the south coast and so the weather here whilst relatively mild can blow up a bit from time to time with salt ridden winds off the sea, even in the summer if this year is anything to go by. I’ve tried mixing my own 3:1 sand and hydrated lime mix and I’ve also tried using a slaked lime putty and sand mix from a reputable supplier for both re-pointing and render repairs but neither seem to last very long here. It just weathers away before it has had time to fully carbonate. I’ve heard that hydrated lime mixes need protecting whilst they are carbonating and this was usually done by covering the area with Hessian but draping huge sheets of Hessian over the entire side of the house would seem to be a bit impractical nowadays. Personally I have been using an NHL2 hydraulic lime mix for my outside jobs, some say it should be a stronger NHL 3.5 but the NHL2 seems to hold up quite well and after hearing the comments from the old lime plasterers, I figured I was probably doing the right thing.

 

[MdB]

I’ve heard that hydrated lime mixes need protecting whilst they are carbonating and this was usually done by covering the area with Hessian but draping huge sheets of Hessian over the entire side of the house would seem to be a bit impractical nowadays.

The above are Gervase's pictures of how he does it.

 

[michael]

Where do you get sheets of Hessian sacking like that? What does it cost? And how long does it have to stay up for? If like me you have to employ a scaffolding company then I’m sure it must cost a small fortune if it has to stay up for any length of time. Further more there is only about 31/2 to 4ft between my house and the house next door and the ancient “twitten” alleyway between the two houses is a York stone paved public foot path therefore scaffolding needs lighting and high vis tape to allow the public to continue to use the path below the first scaffold lift. Council licences for the scaffold and perhaps even for erecting the Hessian have a limited time allowance.
It would be almost impossible to erect a ladder to take the Hessian down, the alleyway is too narrow to get a good angle on the ladder over that height and the alleyway also has a steep fall making the feet of the ladder unstable without propping therefore in my case it would all seem quite impractical.

 

[Roger H]

I would relax a bit. My 3:1 pointing seems fine and I've just sprayed it once a day for a couple of days with a garden sprayer. Mind, the nozzles keep clogging, so I am eyeing up the giant water pistols in Woolworths.

 

[Nemesis]

A google

hessian lime

will bring plenty of places that sell it and also further information.