Plinth painting and limewashing concrete.

[Keithj]

The house is settling down nicely after its traumatic experiences last year. The oak has done lots of shrinking and the gaps have been filled with lime putty, carbonated, and limewashed.

Our craftsman limeman is back, doing the plinth in NHL. He tells me I'll have to put plinth paint on that - the plan is Earthborn silicate paint, one coat 50/50 with water, the next coat 80/20, the last coat neat paint or thereabouts. Is that a good choice and process?

While most of the house is lime rendered, there are some odd bits left with concrete (where there was nothing falling down). There are no concrete-to-lime joins - the concrete is always surrounded by oak. BUT the concrete is, of course, a subtly different colour from the lime - and that spoils the overall appearance.

The plan is to re-do the limewash throughout in about 18 months time. I'm wondering whether a coat of limecrete on the concrete render would allow me to use limewash on it, to have the whole house the same colour (and appearance). Would that work? Is there a better product for that than limecrete?

 

[Penners]

the concrete is, of course, a subtly different colour from the lime - and that spoils the overall appearance.

Does it really? Or is this one of those "problems" that you see, but nobody else in the world would notice unless you pointed it out to them? Sometimes it's easy to get so close to minor details that you tend to lose sight of the big picture.

No criticism or insult intended - just a recommendation for a pause and a bit of reflection, before you go to a lot of expense and trouble.

 

[Keithj]

Oh, no offence taken. But SWMBO minds the different pinks, so I do...

We've ordered some Earthborn silicate black to go on the plinth. That's next weekend taken care of!

 

[middi]

I have to agree with Penners regarding " the big picture"

Whilst it is important for the building to have an Aesthetic pleasing oulook, it is totally inappropriate and useless to apply lime render or limewash to concrete ( cement render !!).
The main purpose of limerich render abutting exposed oak timbers on exterior walls is to facilitate the speed at which rain water can be syphoned by the lime and therefore away from the oak faces and quickly evaporated out into fresh air. Cement render does the opposite.

I fully appreciate that you may understand this cycle, what appears to be " weard" is why would you spend time and money to apply a coat of lime render on cement and then paint it to make it " look good".
If that cement render is that bad that it offends your eye, you might as well buy the nearest matching colour of dulux paint untill you have time to remove the cement render and replace it with lime and then limewash all the external walls.

Middi

 

[Flyfisher]

. . . or have the best of both worlds and use Dulux limewash effect paint on top of the cement render. :wink:

http://www.dulux.com.au/products/dulux-interior-products/effects/product-detail?product=10020

 

[88v8]

'Dulux Design limewash is an interior effects paint that replicates the soft weathered look of traditional lime wash.' :shock:

(my italics)

Ivor

 

[Penners]

Yeah.... :roll:

 

[Keithj]

Right. Got it. The concrete stays concrete and its subtly different shade of Suffolk pink. We'll call it "the character of an old house" for now. When we next limewash, I'll see if we can get a matching shade of masonry paint for it.

The plinth paint is proving interesting, though. The plinth on the concrete bit of the house is black black black. We've been told to put plinth paint on the (new) NHL. But: nobody makes black limewash, and Earthborn silicate doesn't come in black. The nearest they do is grey, and it needs primer (£35 for a tin) then top coat (£120 a tin). That is a bit of a premium, and another colour contrast.

Our local paint shop (excellent blokes, have been very helpful over the years) have a breathable black masonry paint which they would recommend for concrete - but their reaction to lime is "Oooh, tricky. You want limewash for that. We don't do limewash". Can't blame them, since it's not their field and they have a good reputation to uphold.

The breathable black masonry paint they have is oil based; the tin says apply a first coat mixed with 20% white spirit. If I put that on the plinth, is it likely to work? There's no oak in that area: it's brick with some slate under the NHL of the plinth. We don't intend to paint the bricks.

 

[Keithj]

Much research later ...

We decided that modern paint on an NHL plinth wasn't right. Earthborn don't do black, and is 'orribly expensive for the tiny amount we need. It has to be black because all the rest is. Keim was suggested, but I've had that discussion before.

I was looking at a house in Deutschland (a Fachwerkhaus, in fact). That looked very smart, and was clearly oak and lime render and had a nice black plinth. Some asking around eventually revealed that the standard German treatment for lime is Beeck. It's a silicate paint (so the chemical structure of the wall is different thereafter, as with Keim). Beeck have been in business selling this stuff since 1894, and their reputation remains. Das Wort auf der Straße heißt, die Farbe halte jahrzentelang.

The stuff isn't scarily expensive, but the instructions are Vorschrift! You will wire brush down your surface. Then you will etch it to remove the sinterskin, using the appropriate fluid, for no more than 20 minutes, after which you will rinse it off. Then you will apply a fixative coat of pure potash waterglass. Then you will apply a layer of primercoat, mixed with the appropriate proportion of water... (and so it goes on). The final coats of the paint must be applied without dry seams. But the pot of black that I have is as black as a coal cellar at nighttime.

If it really lasts as well as the reports say, I'm going to be very tempted in a couple of years time when exterior limewashing next comes due! The next meeting of the church restoration committee may also have this as an agenda item.

Does anyone have any experience of Beeck to contradict what I've been told/read?

 

[Gervase]

I've used it, and all I can say is, do heed the Teutonic thoroughness of the instructions. The primer is important, as is surface prep.
And be careful of getting splashes on your windows - it will bond to glass.

 

[Keithj]

We've finished! Really finished!

The plinth was done a couple of months ago in NHL and has carbonated beautifully - no cracks to speak of.

Heeding the warnings in the literature and from Gervase (thank you!), I did exactly what was in the instructions. The hardest part was being bold with the Beeck stuff (as is required) while realising how complex the whole process is. Anyway, it's done (völlig nach Vorschriften) and looks brilliant. The black really is black, and at the recommended ratio for the top coat of 90% paint, 10% filler, it was just the right consistency to apply easily and accurately.

The big plus was that it went just as well onto the bits of the concrete of the 1950s front extension where the builder missed it, so the black plinth line is now unbroken.

Did someone say this stuff is good for 100 years? Watch this space!

 

[Penners]

Sie folgte nur Bestellungen!

 

[Keithj]

Die Bestellung erfolgte früher. Die Vorschriften waren mit der Lieferung dabei. Alles klappte einwandfrei!

 

[Penners]

That's easy for you to say.