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re doing the limewash on my earth walls  RSS feed

 
Tys Sniffen
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Location: Northern California
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Well, I may have asked this question before, but I want to clarify and explore:

In my cob house, I have earthen plaster walls and lime plaster walls, and a lot of features, like windows and shelves and doors and counters and tons of stuff I don't want to re-tape to get the walls bright white again.

So, while I try and figure out how to paint a complicated surface while living in it, I also want to know if people here have any experience and advice on how to RE-limewash plaster.

My walls got 6 coats of limewash originally, two years ago now. The dog, the baby and the fireplace have lent themselves to the need to do some brightening.

so now I have these hard lime walls, and I'm unsure as to how to get fresh coat(s) to sink in and not just be a powdery, blotchy mess.

scrubbing the dirty areas seems to mostly take off the white on the raised bits while not really getting out the stains.

Any advice?
Tys
 
John Polk
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Location: Currently in Lake Stevens, WA. Home in Spokane
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A stiff bristled brush should do the trick.

 
Tys Sniffen
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Location: Northern California
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well, no. a stiff brush will clean away things, but what it does is gouge away (sand away/brush away) both the lime wash and the plaster underneath it. and I don't really want to remove the entire surface and put a new (6 coats) back on, as that defeats the purpose of having the nice stuff there now, plus would be a huge mess.

I need to know how to get new lime wash to soak into old lime wash.
 
Jay C. White Cloud
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Hi Yys,

I guess John and I both have missed your point

Do you want to clean it (good dry brushing and a little damp clean - and no the brush should not be removing any of your limewash, if it is or you do have powdering then you previous mix was not correct and you are getting "chalking")

So do you want to clean, or do you want to repaint?

6 coats is a goodly about, if mixed and done well, so I will assume you want to "clean" just to brighten things up. Please note that limewash white walls are difficult to keep bright unless you clean all the time. That is just the nature of light toned wall coverings. Remember also, part of the reason you chose limewash is it's "air cleaning" character which means any "nasties" in the air tends to get drawn to the limewash surface.

Regards,

jay
 
Jay C. White Cloud
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I need to know how to get new lime wash to soak into old lime wash.


O.k. I missed that, but why do you want to add 7th coat?

Either way you have to thoroughly clean the walls, then if you do want another coat, just paint it on as prescribed for the mix you are using. Maybe you would be better served with a "casein paint?"
 
John Elliott
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Tys Sniffen wrote:well, no. a stiff brush will clean away things, but what it does is gouge away (sand away/brush away) both the lime wash and the plaster underneath it. and I don't really want to remove the entire surface and put a new (6 coats) back on, as that defeats the purpose of having the nice stuff there now, plus would be a huge mess.

I need to know how to get new lime wash to soak into old lime wash.


What you want to do is to "whitewash" it. The word means means something completely different nowadays, but long ago, before the advent of mass consumer marketing and infinite choices of paint colors, "whitewash" meant to rewhiten things by slapping another coat of lime on it.

But it's not as simple as it sounds. As you have discovered, there may be stains that not only don't get washed over, they come right back up through the new coat. What you need to do is to get the baby's handprints and the oil from the dog's fur off the wall first. This is usually done with trisodium phosphate (TSP), which still can be found at your local home center, but has gotten a bad rap because of overuse leading to polluted streams. A couple heaping tablespoons in a gallon of warm water should be good enough to get the oils off.

Once you have a clean wall, you can try applying a new limewash. However, adhesion may still be a problem if the surface is very smooth. The usual way of making paint adhere better is to create some surface roughness, so before you put the stiff brush away, maybe you need to use it to not quite gouge the surface, but just rough it up a little bit. The ideal is to take a lot of that 6th coat off, but very little of the 5th coat. Your wash is going to be the new 6th coat.

There are all sorts of things that have been added to limewashes in the past to create better adhesion: water glass, glue, egg white, Portland cement, salt, soap, milk, flour, and dirt. I like the using the salt and flour method. If you add enough salt to flour, the resulting dough is too salty to support any sort of bacterial life and you have a material that is even more lasting than a Civil War hardtack biscuit. You can either add the salt/flour raw to the limewash, or you can try cooking it until the starch thickens. With thickener in the limewash, you may find it easier to apply. Another factor to consider is not to apply wet material to a dry wall; if you let the wall dry after it has been washed, you may need to rewet it to get the best adhesion with the new whitewash.

There are literally thousands of recipes, but you are only going to find what works best for you by a little bit of experimentation. Do your experiments in a small area and after you finish, let it sit for a couple of weeks to make sure it looks like you want it to. If it doesn't, time to tinker with the surface prep or the recipe a little bit.
 
Jay C. White Cloud
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Great advice john...thanks for being more thorough than I was for your first run at this!

Regards,

jay

P.S. have you ever tried Vulpex soaps ( potassium methyl cyclohexyl oleate) if so, what do you think?
 
John Elliott
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Jay C. White Cloud wrote:Great advice john...thanks for being more thorough than I was for your first run at this!

Regards,

jay

P.S. have you ever tried Vulpex soaps ( potassium methyl cyclohexyl oleate) if so, what do you think?


I'm not familiar with that soap. The problem with soaps (as opposed to TSP) is that you need to do multiple rinses to get rid of soap. Sometimes when I clean a surface, I don't want any pesky soap molecules hanging around.
 
Jay C. White Cloud
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Thanks John, great observation. I have to record that one, "no rinse systems are often preferable to systems that require further substrate saturation." That makes good sense as well. I prefer "dry" cleaning systems to "wet" cleaning systems when working on vintage architecture as well.

Regards,

jay
 
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