Spraying Limewash

[sako243]

Does anybody have any direct experience of spraying limewash onto a stone building?

I'm not interested in people proving links to YouTube, other Internet posts etc., as believe me I've searched. I want hands-on experience.

It's reached the point where we need to apply the limewash to our home which is slightly larger than most. I've done so far one coat using the normal method of yard brushes (well okay brushes but we're scaling things up here) on about 100 square metres (only another three or four coats and another 800 square metres to go). It's not been bad applying it with the yard brush but I'm wondering if I can speed up the process a bit.

I've used a friend's Wagner 350M before for the office with standard emulsion and that worked really well. From my research a minimum of about 0.5mm tip is required because of the lime particles in the mix.

Points to note:
- We're mixing from scratch (quicklime) because of the volume needed and therefore cost
- No additives being added (just pure limewash)
- Fresh lime pointing and stone

My main concern I guess with any sprayed on approach is it may dry too quickly.

As said the brush approach isn't too bad, so far 1/3rd of one side of the house has taken a couple of hours to do one coat.

 

[Agroshield]

No experience to be sure, but two things spring to mind:

1) the success of any spraying will depend on the smoothness and consistency (in the sense of being exactly the same all the time) of the liquid being sprayed. What 'quality controls' could you or would you need to put in place to ensure this?

2) could some post-spray treatment (e.g. a very fine mist water spray to keep the general area very humid) assist with delaying the drying?

 

[Gareth J]

I've done it with a mortar gun.

Something like this;

Pardon our interruption...

Messy but did the job.

I don't know if a direct sprayed system would be ok with consistency of whitewash or not.

 

[Blobber]

I should think a decent airless sprayer would work, ive used them in the past with some right thick gloopy emulsion, most hire places stock them so you dont have to buy one

 

[sako243]

So the key thing with limewash is that it is actually almost water. The batch I've mixed up is a milk like consistency. As it's all fresh stone it's better to put more thin layers than a thicker.

There's a lot of contradictory information out there hence wanting hands on experience.

The main concern I have with any spray based thing, particularly outside is it's going to dry too quickly. When I sprayed with my friends 350M it was near enough dry by the time it hit the wall.

 

[Agroshield]

There is one short paragraph about spraying it in here:

https://www.lime.org/documents/lime_basics/limewash.pdf

It does not say much other than giving screening/sieving/filtering recommendations.

Every other document stresses the need to work it mechanically into the surface with a brush for best effect. So even if you spray apply it, you still have to scrub over the surface.

 

[sako243]

Well I had a new spray gun in the workshop so I thought what the hell...

As you can tell it's been in use.

And the scale of the limewashing to do...

So the room far right was done as an experiment but put on much thicker than we have been doing. After I spoke with the chap who had a local woodyard and limewashes his house the big batch I've made is much thinner, almost watery.

Above the first lift of scaffolding was done with a brush over 2 days. Everything below the first lift I've just done with the spray gun with a 2.5mm nozzle.

@Agroshield I've seen all the references to working it in with a brush but they've usually also been referring to a single cream consistency which is a lot thicker than what I'm putting on. I think the working in is mainly down to making sure it gets into all nooks and crannies.

Based off brushing it on above and just spraying it on now I wouldn't have said there's any difference to how it's gone on. This will be a real test though as today is meant to be a good day and tomorrow wet. The lower bit of the wall is reasonably well shaded so I'm hoping it won't dry too quickly but go off quickly enough for the rain for the next couple of days.

If this works then quids in - it's a hell of a lot faster than brushing it on even if I only do a few square metres at a time before having to refill.

For reference it's a 2.5mm nozzle, I had to remove the filter at the bottom of the hopper (wasn't installed by default but I thought I'd try but it's too fine). I don't think I'd want a bigger nozzle, this is actually just about perfect compared to brushing it on.

 

[sako243]

The mix is roughly a 25kg bag of quicklime to a 50 gallon drum of water for reference. Mixed with a plaster mixed on the end of a rather small Milwaukee drill but it's handling it like a champ.

 

[500e]

We use airless for concrete wall finish they do it on all the block work, not tried lime though will ask the question about lime.
Had reply neither of the lads who do the spraying have used lime and dont know anyone who has either 2Sorry2

 

[steve t]

What about a schutz gun with a tube on it into bucket of lime wash?

 

[Dcal]

Well I had a new spray gun in the workshop so I thought what the hell...

As you can tell it's been in use.
View attachment 447359
And the scale of the limewashing to do...
View attachment 447360
So the room far right was done as an experiment but put on much thicker than we have been doing. After I spoke with the chap who had a local woodyard and limewashes his house the big batch I've made is much thinner, almost watery.

Above the first lift of scaffolding was done with a brush over 2 days. Everything below the first lift I've just done with the spray gun with a 2.5mm nozzle.

@Agroshield I've seen all the references to working it in with a brush but they've usually also been referring to a single cream consistency which is a lot thicker than what I'm putting on. I think the working in is mainly down to making sure it gets into all nooks and crannies.

Based off brushing it on above and just spraying it on now I wouldn't have said there's any difference to how it's gone on. This will be a real test though as today is meant to be a good day and tomorrow wet. The lower bit of the wall is reasonably well shaded so I'm hoping it won't dry too quickly but go off quickly enough for the rain for the next couple of days.

If this works then quids in - it's a hell of a lot faster than brushing it on even if I only do a few square metres at a time before having to refill.

For reference it's a 2.5mm nozzle, I had to remove the filter at the bottom of the hopper (wasn't installed by default but I thought I'd try but it's too fine). I don't think I'd want a bigger nozzle, this is actually just about perfect compared to brushing it on.

If that gun works, I'd get yourself a pressure pot, it will be a lot easier on the arms, as you don't have to hold the weight of the paint in the gun, and also quicker as you won't have to refill as often.
I wouldn't go mad on the pressure pot volume as the lime might settle so it needs to be used fairly quickly.

For the same output, a pressure pot needs a smaller nozzle than a gravity, at a guess 1.8 fluid tip against the 2.5 you have.

I haven't sprayed lime but I did spray a tank coating that a proper industrial Graco airless high pressure set up couldn't.
I ended up using a gravity hopper gun like the one @Gareth J linked to but it got old very quickly. (Did the job though)

The proper setup for the product had a peristaltic pump to get the coating to the gun that was very specialised.

 

[8ob]

I've done it with a mortar gun.

Something like this;

Pardon our interruption...

Messy but did the job.

I don't know if a direct sprayed system would be ok with consistency of whitewash or not.

They are good, bought one to spray the stables with, it used that gloopy trade emulsion straight out of the tub.

 

[jsf55]

What about a schutz gun with a tube on it into bucket of lime wash?

We used too spray calcium carbonate mix on too our casting moulds with one, the difference being they were quite hot and the water evaporated quickly, i think it's too big a nozzle size for that

 

[sako243]

If that gun works, I'd get yourself a pressure pot, it will be a lot easier on the arms, as you don't have to hold the weight of the paint in the gun, and also quicker as you won't have to refill as often.
I wouldn't go mad on the pressure pot volume as the lime might settle so it needs to be used fairly quickly.

The pot I've got is no bother on my arms, compared to scrubbing stuff on with a yard brush it was a doddle even up a ladder.

The lime does settle so I'd be against that. Previously we filled a lick bucket up and because the brush was always in and out and it was being moved about on scaffold it didn't settle. When I was going back and forth to the 50 gallon drum I mixed up every four or five refills I was having to remix it.

I think I used about the same volume as before with the brush for a similar area so no more than 4 or 5 gallons. Plan of attack now is the compressor is strapped to a pallet ready for rapid deployment by the wee tractor. Mum's popping over to help and basically be a gopher so we'll fill up a dozen or so 2 litre milk bottles (she has loads of them in one of the barns). That way it's easy to decant and can give it a good shake before pouring into the gun. I spent most of my time back and forth moving ladders and refilling as I was just experimenting. We're fairly* sure it's as good as we've been brushing on so going to streamline the process now.

* Unfortunately what looked like it was going to be an overcast day turned into a scorcher of an afternoon, the wind also picked up and someone popped around unexpectedly so we didn't keep an eye on it. It looks like it's dried out too quickly with the stack of unseen events and become a bit powdery. We'll scrub it with a brush before the next coat goes on but we've got a couple more heavy days of rain forecast then two overcast days which should be ideal.

 

[Roger440]

Ive got all this to come, so following with interest. Though ive got to re-point the whole thing fist, so will be a while yet!

Did you not consider one of the more modern alternative with comparable breathability to lime wash. Lime wash, great as it is, in my limited experience seems to need doing quite often. With your house especially, the novelty would wear off quite quickly i think!!!

 

[sako243]

I did. I've got a friend from the Welsh shooting team who runs a big company specialising in old buildings. He recommended a paint based ECO something or other which is breathable. When I actually got down to it with the manufacturer they wouldn't recommend leaving it any longer than you can get away with with limewash.

The chap down in the village last limewashed his house during the start of COVID and just put another coat on, so about 4-5 years which is what the manufacturers were saying would be pushing the modern alternative. I think I worked out we needed about 100 gallons to do the 1/2 of the house we've repointed so far. Projected cost of the paint was north of £10k I think, plus then actually getting it on there.

I spoke with Ty Mawr about their ready made limewash and about whether I could get a discount given the volume. Chap said of course and then quietly said have you thought about making your own? He then phoned a friend in the company and verbally told me the recipe for the wash they make. I was actually just about to set off to Brecon to pick up some quicklime from them when I thought I'd call in at the local builders merchant down the road. They had most of a pallet of quicklime left over from a job (Tarmac lime rather than Ty Mawr). The boss then phoned up their rep and got them to confirm it could be used.

To date the 6 bags required to do the 4 coats on the house so far have cost £36. Roughly a bag to 3/4 of a 50 gallon drum of water so pennies in water. A huge saving.

The spray gun seems to be working quite well. Tomorrow is going to be the real test as its looking like a good day for it again. Longer term I've got a 16.5m cherry picker which once I fix a few things I bent and get the 6x6 running will make things easy. I was planning on running a mains cable, pressure washer line and airline up to the basket with fittings down on the deck. That way things can be plumbed in easily for maintenance on the house.

Maybe I should do this rather than electronics... In fact the fiancé looked quite keen on trying the spraying so maybe it can be more profitable for her to do that than nursery work

 

[Gareth J]

*Lime pedant alert* I suspect that the stuff you've bought from the builders merchants is hydrated lime, rather than quick lime. I may be wrong but haven't seen quick lime for sale at one before. Hydrated lime if pretty fresh should be as fine for lime wash.

Think you made a good choice, £10K on paint isn't sustainable no matter what it says on the tin!

 

[sako243]

No it's quicklime. Even says it on the bag

Quicklime - Calbux 90 - 25kg

Eco paint, eco friendly natural paint & decorating suppliers. Sustainable building materials, lime products & natural insulation. Earthborn, Farrow & Ball, Osmo, Auro.

www.celticsustainables.co.uk

It's a local builders merchant (only two depots). The pallet was from a job the associated builders (same guy started the merchants after he was keeping a load of stock for the building firm) had done. The quicklime is almost exclusively shipped on a pallet due to its nature so they had to buy a pallet and then used half a dozen bags and the rest stayed on a shelf.

 

[julianf]

watch your lungs and eyes

ive never had significant issues with limewash, but ive made my hands bleed from nhl in the past

 

[minimutly]

I have one of those buckets with a pump, hose and wand with a nozzle attached. Not used it for 30 years.
Must be rare, can't find one on ebay...