question to the lime experts

[Anonymous]

Hullo all.

We are hoping to start limewashing internally somewhen over the next six weeks, as a limewash virgin I have a couple of Qs. What we intend is to coat everything in unpigmented lime, walls and ceilings, to move in. Once we have lived with the light for a bit we will see if we can be bothered about colours.

Should we buy premixed limewash, or pure putty and water it down ourselves? If so how?

Is there any rule of thumb regarding coverage?

Is there anything else I have probably forgotten about and will jump up and bite me in the bum later <IMG SRC="http://www.periodproperty.co.uk/discussing/smileys/smile.gif" BORDER=0 ALT=""> ?

All advice appreciated

Steve

 

[Anonymous]

Do it yerself - it's a fraction of the price and you get more control.
Use a fine lime putty ready-bought in tubs, unless you've got a couple of months in hand and fancy making your own. And then you'll need water. As to how much; there's no absolute, hard'n'fast rule about proportions. Much will depend on the weather, the humidity, the porosity of the substrate.
As a rough rule of thumb, though, start with one measure (jug, bucket, scoop or whatever) of putty to three of water. More water (say 1:4) in hot, dry conditions and with very porous substrates, more lime (say 1:2) in damper conditions and with less porous substrates) Mix it up with a drill-mounted mixer and then add either one pint of skimmed milk to each 20 litres of wash or a quarter of a pint of boiled linseed oil. I tend to add the casein to limewash for indoor use and the oil to limewash for outdoor use. Both additives are to give the limewash better adhesion to the substrate and to reduce the likelehood of it flaking off and dusting.
Apply to a clean, pre-wetted surface - invest in a pump-up sprayer like a five-litre Kilaspray with a wand or similar to make life easier - using a four-inch brush and don't be surprised if you find yourself looking at what appears to be merely a damp wall.
Limewash should always be applied thinly, and will appear transparent when it first goes on. It will become opaque as it dries and carbonates. The drying process should be slowed as much as possibe to aid carbonation - so on sunny or windy days you want to screen any freshly limewashed surface with damp hessian or plastic sheeting. And get used to filling up your pump-action spray to keep the fresh limewash damp!
Keep stirring your bucket every so often, as the lime has a tendency to settle to the bottom, and you can find yourself starting with a thin wash end ending with clotted cream. Aim to keep the consistency consistent.
You should be able to recoat within 24 hours.
Inside the house, three coats should give you nice, flat matt, opaque finish. Outside I'd say five coats is the minimum.
If you change your mind and want colour, no worries - just add a couple of coats of pigmented wash over the white. Do make up as much coloured wash as you think you'll need, though, as it's a#####to match, given that the wet wash in the bucket is much darker than the dry wash on the wall.
As for coverage - much depends on the porosity of the surface you're washing and your proportions, but 20 litres should cover around 30sq metres.

 

[Anonymous]

Thanks Gervase for the excellent response. If I may be so rude as to tap your experience a little more:-

The surface is fresh lime plaster in an unheated house - so is that about 3:1 given a very porous surface but cold damp conditions?

The 20l = 30msq - is that mixed limewash or putty per msq?

How much diff in coverage is there between coat one and coat 3?

I have read elsewhere you should leave 4 days between coats for carbonation - are they just being OTT?

Ta V much <IMG SRC="http://www.periodproperty.co.uk/discussing/smileys/smile.gif" BORDER=0 ALT="">

Steve

 

[Anonymous]

You'll read all sorts of things, much of it horribly conflicting. For example, jane Schofield recommends 2:1 water to putty mix, while Patrick McAfee says 8:1. Trial and error is your best teacher - start at around 3:1 and adjust accordingly.
The first coat is the one with the least coverage - it's the one that the plaster will slurp up, even though it's been wetted. And, as for wetting, I find the best way is to give a good soaking an hour or so before you apply the limewash, and then 'top up' with a fine mist spray just before you start slapping it on - do about a square metre at a time.
By the time you get to the third coat you'll be covering a lot more, so the 30sq meters is an average (and that's from 20 litres of mixed limewash at 3:1)
As for carbonation - four days would probably be perfect, but I tend to strike a balance, and have found that another coat the same time the following day doesn't harm. If you're doing a whole house, you'll find that by the time you come round again to where you started, there'll have been plenty of time for carbonation!

It's messy work, by the way. You will splash a heck of a lot. Obviously that means taking care of your eyes and skin, but it also means covering any sensitive plants under your 'fall-out' zone, and washing down paths and other bits that get splashed before the stuff carbonates. Dilute vinegar is a good way of getting limewash off windows and woodwork.

 

[Anonymous]

...and I certainly wouldn't call myself an expert, by the way. There are probably others here with vastly more experience; I'm just relaying what has worked for me. It's not exactly rocket science!

 

[Anonymous]

I think this is an appropriate spot to reveal the, as yet, unanswered Quiz. The official translation is as follows:

"The people of Sifnos must use a lot of chalk to get it all so white."

But I think it should be limewash, rather than chalk.

 

[Anonymous]

You found no probs with the milk? I have heard (on an unreliable grapevine) that its smelly and attracts mould so casein powder should be used....

Oh btw, I have seen you on telly and that is definately an expert's beard if ever I have seen one. If it gets any better Oxford will be offering you a chair <IMG SRC="http://www.periodproperty.co.uk/discussing/smileys/smile.gif" BORDER=0 ALT="">

Steve

 

[Anonymous]

Milk stinks when the fat goes rancid - if you use skimmed milk then the protein (casein) is there, but the fat isn't. Powdered casein is good stuff, but milk is so much cheaper!

PS: The beard is excellent for plastering - a few tufts in the mix here and there help bridge the largest gaps!

 

[Anonymous]

And when you lose the brush for the limewash?

 

[Anonymous]

i made up a plastic drum (with screw down lid) of limewash to do my whole house. i used 50 kilos of hydrated lime (2 bags) and 100 litres of water. for exterior use i added 750mls of raw linseed oil. it has worked a treat, even over flintwork. make your own!

 

[Anonymous]

I was always under the impression slaked lime putty was better than hydrated lime, is that wrong? Given the price difference (mainly in getting putty shipped to IoW) I'm extremely curious.

 

[Anonymous]

Slaked lime putty is probably more of a reliable banker than hydrated lime powder.
With the powder there are a few variables.
You need to get it from somewhere with a high turnover, so that it's as fresh as possible, because it will start to carbonate in the sack. A month or two hanging around in a warehouse and you'll have a bag of whiting, not lime.
So, if you want to use hyrated (and there's no reason why you shouldn't) you need to find a builders' merchant you can trust and to establish that any lime you get from them will be straight from the kiln. But how can their wholesaler guarantee freshness? All in all, it's a gamble.
Given all that, I find it easier and more reliable to use tubs of putty. Even shipped to the Isle of Wight, it shouldn't prove exorbitant.

 

[Anonymous]

Point taken, and I really should have some putty to hand anyway for continued care and repair <IMG SRC="http://www.periodproperty.co.uk/discussing/smileys/smile.gif" BORDER=0 ALT="">

 

[Anonymous]

the only difference between the production of putty and hydrate is the amount of water added to quicklime in the production process (less for hydrate).... dry hydrate (which can now be obtained in bags with a plastic inner just like opc) is what i have always used..... no problems what so ever. why pay more?