Limewash vs clay paint vs something else

[LadyArowana]

I'm envisaging a volcanic eruption taking place in Toby's kitchen when he reads this

It’s all in good fun though, people passionate about their craft are a rare and treasured breed nowadays. My heritage blacksmith is in similar vein and bristled at the term fabrication Luckily I am now returned to good standing as he approved of my design for some potential work, just need the CO to be persuaded. He won’t work on things if he doesn’t like you or your project, which apparently a billionaire owner of some country estate has discovered in relation to some gates!

 

[skybloo1]

Not true.

They are vegetable starch, cellulose based thickeners and simple salts (from cotton) they contain zero plastics.

Pardon my error - we’ve just been ultra cautious after going to such lengths to try and achieve a breathable house

 

[noj]

A lot of the pre-mixed pastes do have added PVA, one example:

Anaglypta Ready Mixed Wallpaper Adhesive

There's no time wasted when you use Anaglypta ReadyMix wallpaper adhesive. This high-performance aqueous paste is ready to use as soon as you open the lid - simply roll or brush it on, straight from the tub.ReadyMix is suitable for most types of wall covering or lining paper, and can be pasted...

www.toolstation.com

 

[Toby Newell]

A lot of the pre-mixed pastes do have added PVA, one example:

Anaglypta Ready Mixed Wallpaper Adhesive

There's no time wasted when you use Anaglypta ReadyMix wallpaper adhesive. This high-performance aqueous paste is ready to use as soon as you open the lid - simply roll or brush it on, straight from the tub.ReadyMix is suitable for most types of wall covering or lining paper, and can be pasted...

www.toolstation.com

Again, not true.

95%+ of pastes are made from vegetable starch, cellulose based thixotropic binder and salts.

Adding PVA to a normal paste mix is a well known formulation for heavier textured papers like anaglypta which is most often coated with vinyl, making any breathability issues rather moot. Virtually no pastes for normal paper based wallpaper contain PVA. I guess if there is a vogue for dumbing down wallpaper hanging and that adding a little PVA is useful to aid lubricity and positioning then that is a good thing. I never tried hanging paper, it looks difficult!

If you have a very heavy paper or one that is not very porous normal paste will not hold it, so it's all rather moot. Either you need it or you don't. The vast majority of pastes are pretty much organic based.

Furthermore, PVA is hydrophilic and highly breathable anyway, you have to pay several multiples more for a resin modified waterproof D4 PVA than your bog standard 'Unibond' sealer. I am guessing the wallpaper bods are using the cheaper £10 quid a gallon, rather than the D4 modified £70 quid a gallon PVA as paper, however textured, isn't exactly heavy when compared to wood. I am pretty sure (for the same film thickness) that a paste containing a few % of hydrophilic PVA has virtually identical breathability properties to one without.

Myths, myths and more myths, I know, its boring, I did courses on polymers and have been to factories, but polymer is a massively broad term, there are natural and synthetic polymers, the majority of which of are partially or very breathable, (exceptions being PMMA, Epoxides, Highly crosslinked PUs, ABS for example) normal PVA is one of the most permeable and is at least as breathable as cured linseed oil.

It's pretty much exactly why it's used as a sealer! If it had very low permeability paint or plaster wouldn't bond to it! The idea is that PVA allows water through! Just slightly less than no PVA.

No idea why people persist to promulgate recieved wisdom without bothering to check!

I lie. I do. Because strangely the truth is often harder to find because it involves study, reading books and research papers and engineering and science journals. Whereas reductive errata is freely promoted on thousands of websites, including news outlets, wikipedia and university websites due to laziness.

As skybloo1 says being cautious is often a good insurance policy and a lot less time consuming. I approve, I am very risk averse, I only study to reassure and give myself confidence. Which is the only reason why I have gone from 25 years ago refusing to fill any gaps or replace a single board, to pretending to be a part time conservation timber framer.

I am aware pointing out mistakes is as about as popular as drowning kittens but I simply aim to help keep this repository of information as accurate as possible within my very small and limited sphere of knowledge.

Am pretty sure that to maximise breathability of lime based plasters you would want to omitt the wallpaper altogether and apply something like a casein based paint direct to the plaster.

By all means poo poo things you know little about based on random things you have heard / assumed / reductively reasoned, I think it's rather the wont of the organically minded, like washing your yoghurt pots before they go to landfill / get burnt / sent overseas.

You can leave the boring, sciencey deductive stuff to me. Carry on... blimey it's hot.

 

[Toby Newell]

Pardon my error - we’ve just been ultra cautious after going to such lengths to try and achieve a breathable house

Ultra cautious and thus worrying is a good thing! And a sign of intelligence. I need a few month / years run up and / or weeks of research / study before I try something new.

 

[Toby Newell]

I'm envisaging a volcanic eruption taking place in Toby's kitchen when he reads this

Pledge would work very well in a kitchen, highly waterproof and chemically resistant. The only issue is you could never change the coating. I mean that and the neck insurance.

 

[Zebra]

Buy some pigment from Ty-Mawr. I use their Burnt Sienna, I think, I'll check.... which, mixed pale enough is a kind of oatmeal colour. They sell tester pots which are quite enough for me. A 15ml measuring spoonful mixed to a paste in a little warm water then gradually mixed with a coffee cupful of putty, then three coffee cupfuls of water makes a litre of limewash. Or thereabouts. You can play about with the mix. I used to do 20ml spoonful per litre of limewash but prefer it paler.

Correction! I used 15ml of pigment to three litres of limewash, not per litre!!!

 

[steveb]

Correction! I used 15ml of pigment to three litres of limewash, not per litre!!!

Oh no, there was me trusting you and waiting for it to 'dry lighter' and now tell me my wall is going to look like cat sick forever

 

[Zebra]

Oh no, there was me trusting you and waiting for it to 'dry lighter' and now tell me my wall is going to look like cat sick forever

Oh no!!!!

 

[Toby Newell]

Oh no, there was me trusting you and waiting for it to 'dry lighter' and now tell me my wall is going to look like cat sick forever

Your cat has sick the colour of burnt Sienna? I would see your vet...

 

[Tilly71]

Been reading F&B estate emulsion is very good for internal wall breathability. Can anyone advise me on the F&B modern emulsion paints and are they good for letting walls breath as I need to paint the kitchen soon. Thx

 

[a twig]

If you read some of the preceding posts in this thread it has already been covered

 

[Tilly71]

Thanks, just read through this entire thread but nothing mentioned F&B Modern emulsion. I’m happy that estate emulsion lets walls breathe fine but the modern emulsion designed for kitchens/bathrooms so was looking for advice on that product alone

 

[jamest]

I confess to having looked into this previously. The good thing is that F&B have the decency to publish figures for the breathability of their paints - if you know where to look. You want the product advice sheets. For modern emulsion, the sd value (a measure of vapour permeability) of modern emulsion is 0.38, which is not really very 'breathable'. I wouldn't paint my walls with it. If you use the recommended primer, it's even worse as this has an sd value of 0.5. With both, the result is (presumably) additive, giving an sd of at least 0.88 I would imagine (more if you use more coats). So, if it's breathability you want, steer clear of modern emulsion and the primer. The primer isn't really necessary, but without it you'll need more coats of the emulsion, and the more coats you slap on, the worse the breathability. I image that the listed sd values are for one thin coat - think doubling it for each coat, so two coats of modern emulsion you'd be looking at an sd value closer to 0.76 (at least that's my assumption - it may be worse than that or it may be a bit better, but as I said, I wouldn't be sticking it on my walls).

 

[Toby Newell]

F&B estate emulsion SD = 0.01

Any true 'chalk paint' will be similarly breathable, that is why they are 'chalky' they have very little binder.

 

[Stevers]

To paint our partially tanked basement walls I have bought a 10L tub of Leyland contract matt emulsion (it was cheap). It will be lightly tinted to 'Gardenia' a very light cream colour. I had just assumed it to have similar breathability to F&B estate emulsion, but Leylands technical data sheet doesn't give an SD value.

Fifteen years ago the chief damp proofing wally was happy for me to use either a generic contract emulsion or F&B estate emulsion, and both have lasted well. It has to be said though that the much more expensive F&B estate emulsion (below dado) does give a better finish than the Albany contract emulsion (above dado, and ready tinted to gardenia) that I used last time. Albany is the in-house brand of Brewers the Decorators Merchants, so could of course have been made by any of the paint companies including Leyland.

 

[a twig]

Thanks, just read through this entire thread but nothing mentioned F&B Modern emulsion. I’m happy that estate emulsion lets walls breathe fine but the modern emulsion designed for kitchens/bathrooms so was looking for advice on that product alone

Right you are - apologies, misread your first post!

 

[Tilly71]

I confess to having looked into this previously. The good thing is that F&B have the decency to publish figures for the breathability of their paints - if you know where to look. You want the product advice sheets. For modern emulsion, the sd value (a measure of vapour permeability) of modern emulsion is 0.38, which is not really very 'breathable'. I wouldn't paint my walls with it. If you use the recommended primer, it's even worse as this has an sd value of 0.5. With both, the result is (presumably) additive, giving an sd of at least 0.88 I would imagine (more if you use more coats). So, if it's breathability you want, steer clear of modern emulsion and the primer. The primer isn't really necessary, but without it you'll need more coats of the emulsion, and the more coats you slap on, the worse the breathability. I image that the listed sd values are for one thin coat - think doubling it for each coat, so two coats of modern emulsion you'd be looking at an sd value closer to 0.76 (at least that's my assumption - it may be worse than that or it may be a bit better, but as I said, I wouldn't be sticking it on my walls).

Thanks for your reply, what paint would you recommend in the kitchen / bathrooms? I have used estate emulsion in a kitchen before and it’s not good when removing any stains.

 

[jamest]

Thanks for your reply, what paint would you recommend in the kitchen / bathrooms? I have used estate emulsion in a kitchen before and it’s not good when removing any stains.

I'd be loth to offer any advice per se, but if it were me it would depend upon the wall I was painting. If I had a wattle and daub wall or a cob wall, I wouldn't use anything other than a very breathable paint (sd no more than 0.03 or 0.04). Same for sold brick walls with a breathable insulation system applied to them - I've used the cork board system by seciltek on some of my single skin brick walls and put estate emulsion (no primer) on them. However, whatever breathable paint you use, it will be moisture absorbant to a degree and so it'll be hard to get rid of some stains. Some exterior lime washes have added oils or tallow in them and that helps shed water, so you could try those internally - I don't have any experience of that, I've used the ingilby paints one externally and the lime paint by Bauwerk, but being external I've never worried much about a few stains. Both companies are very helpful if you ring them up - though that may have changed for Bauwerk post Brexit.

If I were painting an upstairs bathroom with a solid external brick wall, I probably wouldn't worry too much about the breathability of the paint - I'd be more worried about ventilation. Having said that, I would avoid any paint with plastic in it. F&B's Modern Emulsion would probably be OK. It's breathable-ish (class II rather than class I).

 

[Tilly71]

Need to cover old water stained plaster. Root cause of staining resolved now, oil based undercoat seems recommended the best stain blocker but won’t allow the plaster to breathe, any recommendations would be greatly appreciated.