I need the recipe for tadelakt

I want to use a waterproof plaster on cob called tadelakt. I know it's a lime plaster that can be made waterproof using black soap or olive soap. However I am unsure how to make it. Does anyone have the recipe for tadelakt?

Here is one from a web search I just did.

http://lacumbreverde.com.ar/TadelaktEnglish.htm

Yeah I found that one also. He says it's an imitation and should have the same result. I am trying to find the traditional recipe. I suppose if I can't find the original I will be stuck with that one.

Hi Christian,

Be careful with this as you can trap moisture in a wall assembly if you are not well versed in it's use and application. I like that you are trying to do this traditionally, but the best teachers are in the Middle East and Mediterranean region, few speak or write English. Here are some links that may be useful. You can also try searches with": التدلكت التقليدية or tadelakt tradizionale

http://www.puretadelakt.com/

http://www.earthpigments.com/products/index.cfm?product_id=129

http://www.mikewye.co.uk/Tadelakt_Training_Course2.htm

http://tadelakttradizionale.blogspot.com/

http://www.tadelakt.it/

http://limeworks.us/

http://www.rosendalecement.net/index.html

Regards,

jay

Thanks for the links. I have been busy digging through the web also. This is one hard to locate recipe. It seems most westerners buy their tadelakt plaster and learn how to apply it. It just doesn't seem as fun to me.

I found this http://ecobrooklyn.com/tadelakt-moroccan-plaster-technique/

"The key ingredient of Tadelakt is 95% burnt limestone, with the other 5% being the sand and ash resulting from the burning process."

Update:
I looked up the book they that they took this from. The reviews say there is nothing in the book that tells you how to make it. That's strange.
http://www.amazon.com/Tadelakt-Michael-Johannes-Ochs/dp/0393732959

I looked up burnt limestone and found out it should be Calcium oxide. I am looking for a local source now to test it out. If your going to try this make sure you know what you are doing as adding water to calcium oxide can cause a caustic reaction.

Update: It looks like I can just skip a step and get Calcium Hydroxide mix it with water and apply it. I expect i will add the 5% the author suggested in his book. I will let you know how it plays out.

What you are proposing to do is basically the imitation that you mentioned in your second response in the thread. You can do an imitation tadelakt - which is basically lime plaster treated with olive oil soap (and hand rubbed with a smooth stone). What makes tadelakt is the particular type of limestone that is burned and slaked. The lime that is typically sold (type S, type N, etc.) is much much purer than tadelakt lime. The large amount of impurities in tadelakt lime is why you don't have to use much or any sand in it. The impurities essentially act as aggregate. If you use store bought lime you will probably have to add quite a bit of sand to get a durable surface.

Hi Christian,

I still have not found my mother's recipes for this.

I also have not read you reference to 'Black Soap,' which is a key ingredient.

I also agree with Ardilla, about the type of lime and not skipping steps or substituting, as this can greatly affect outcome results, if you want a true Tadelakt finish that is very durable.

Regards,

jay

I don't want to make artificial tadelakt. Where do you go when you don't have the recipe? You have to improvise until you get it right. I don't know any other way than to keep trying.

Hi Christian,

I understand your frustration, (not finding my mother's is driving me a tad nutty.) She made her lime from burned oyster shells while on the beach the few times she made it, so whatever lime you use, it needs to be a facsimile of that. Then the black soap was part of the burnishing process from what I can recall in helping her. I will keep looking and please keep us updated.

Regards,

jay

If needed, here's a how-to on burning shells for lime from Turkeysong: http://turkeysong.wordpress.com/2011/03/06/lime-squad-i-a-photoessay-on-lime-burning/

Christian McMahon wrote:I don't want to make artificial tadelakt. Where do you go when you don't have the recipe? You have to improvise until you get it right. I don't know any other way than to keep trying.

If you don't want to purchase Morrocan lime that has been exported or mix an artificial recipe, you are stuck. You probably won't be able to find gradational and chemical analyses of the real thing. Even then you would have to try to replicate it by analyzing the source materials for your mix. When you are dealing with natural materials (i.e. limestone) but need a specific performance you need to accept substitutions and adjustments or get the real deal. By choosing any other sources of lime, limestone, oyster shells, etc. you are making an artifical mix - which means there is trial and error involved. The recipe you are looking for assumes that the materials listed in the recipe are consistent location to location which they are not.

Personally, I am not willing to pay the high price for Morrocan lime. The mark-up for this 'designer' product is too high. So I make recipes like the link that was already included. The sand, cement, marble dust substitutes for the silicates and unburnt carbonates in tadelakt lime.

Hint: If you are going to make lime putty from bag lime get the putty soaking as far in advance as possible. The longer it soaks the better. I have lime putty that has been soaking for more than a year that is really nice to work with, however, a month or two is almost as good. Also, many pottery supply stores will carry the marble dust (sometimes called whiting or calcium carbonate powder).

Just a suggestion here, folks.

What we are talking about here are impurities in the lime plaster and what they end up doing to the eventual dried surface. Put organic molecules in any sort of aqueous slop (like plaster) they are not soluble in, and are going to separate into a different phase. When this happens slowly while you are plastering a wall, the soap/oil/wax/bear fat rises to the surface and ends up making a waterproof coating. Modern water-based paint technology is based on latex, an insoluble organic molecule, but when it is smeared on a wall and the water dries, it leaves an organic, non-polar surface that is easy to clean up. A similar waterproofing effect I have seen is where little balls of beeswax are shot out of a spray gun and each one deposits a little bit of wax on the wall before it falls to the floor. You sweep the floor, reload the spray gun and after 2 or 3 passes, you have a nice surface coating that keeps friable plaster from flaking off or becoming airborne dust.

I wouldn't advise getting obsessed about replicating a particular recipe. Remember that these techniques have been passed down through the ages and they were developed by people who worked with what was available around them. Around the Mediterranean, olive oil is plentiful, so adding olive oil soap to the plaster mix was tried, maybe purely by accident, and they noticed that there was a nice effect. In the Sonoran desert where olives are not so plentiful, but jojoba beans are, maybe you can get a similar sealing effect by letting your plaster dry and then giving it a good massage with crushed up jojoba beans.

The key to a taking a locally available material and making good building material out of it is to be observant. Make a few small batches, try them out. Experiment with additives. Know the chemistry of the mix and what adding each ingredient does to the overall properties.

I agree with with you John about not getting obsessed about recipes and also knowing what the substitution does to the properties of the material. This is very important in this case.

The fats in the soap actually form a chemical complex with the lime in the layers of plaster. It isn't just a coating. So less mobile or non-soponified fats applied to the surface won't do the trick. It is important that the soap be applied after the plaster goes on the wall. If you mix the soap in with the plaster before applying the plaster you will not get good results. The soap does have to be applied before the plaster cures as well.

You shouldn't substitute for non-soponified fats either because that is important to the chemistry that forms the lime-fat complexes. If you tried to apply olive oil instead of olive oil soap - you get something altogether different (a softened, darkened plaster prone to sloughing and going rancid).

There are all sorts of olive oil soaps on the market. I have used the Kiss May Face brand of olive oil bar soap. It just gets diluted down and put in a spray bottle. Since it is readily available - I don't try to reinvent the wheel with a different substitution. Other types of oil soap may work, but I've never tried them.

I have done some more digging, and though mom's recipe eludes me still, I have gotten a few craftspeople to give me some insight. (Very proprietary bunch...but I like them.) Here are some clear recommendation, let me know if you test it, and post some pictures if you do.

Buy one of http://limeworks.us/ecologic_more.html lime plasters and mix accordingly to their directions.

With the finish coat, add 2oz. per pound of plaster, (experiment here as I got from 1oz to 5oz from sources) of black soap. http://www.earthpigments.com/products/index.cfm?product_id=129

Now, one of the folks is also a timberwright, and tells me that a single application of 'Land Ark' (exterior grade) http://www.heritagenaturalfinishes.com/ applided just as drying is complete and buffed and burnishded out (maybe with a bit of rendered beeswax as you buff) has the same effect, and conditioning.

I am confident that you will find a formula that works for you. Please share and post pictures.

Regards,

jay

Thanks everyone for your posts. There is some really good information here. I expect a traditional tadelakt could be possible now.

Here is the recipe and basic instructions I learned from Ryan Chivers during a tadelakt workshop this spring in Portland. (http://www.artesanoplaster.com/ryan-bio.html) He works out of Boulder, CO and traveled to Morroco to learn the traditional way. We used both NHL and Type S lime for our project, and the Type S was much easier to work with. A slower setting time, and it seemed slightly less caustic as we mixed and applied it without worrying about gloves.

Here is your mystery ratio... 1:1
type s lime : calcium aggregate (i.e. crushed marble, swimming pool sand)

it is important that your aggregate have at least 10% volume that fits through a 200 mesh screen (fine enough to fit through a window screen) and not exceed a size of 20 mesh. You can get fact sheets given to you by your local builder supply store that supplies aggregate on the particle sizes. They are a bit tricky to read, but ask for help and describe the size of what you need and they can work with you. I know a marble tile layer who cuts many tiles and is left with a lot of powder. I use this marble powder to amend my swimming pool sand. Without these very fine particles, your burnished plaster does not come out as smoothly.

The famous black soap that you speak of is this one. http://www.marius-fabre.com/fr/17-savon-noir-a-l-huile-d-olive/112-savon-noir-en-pate-1-kg.html A little goes a long long way. One order of this might be enough for a lifetime of tadelakt projects.

Up to 10% of a lime plaster mix can be pigment by volume. This will give you room to play with colors. Adding more than 10% by volume can cause structural failure to the curing of your lime plaster.

In my experience, tadelakt is all about timing. You have to know your substrate, how much water it will absorb, how many layers to put on, when to burnish it with your stainless steel trowel, and when to burnish with a stone. Start with a cob ball. Let it dry, then remove the straw with scissors or a torch, or rub smooth to the shape you want it with a brick or file. Dip your cob ball in a bucket of water, very quickly so that only the surface absorbs moisture. Take tadelakt mixture and apply first layer with a damp sponge to your cob ball not worrying about your finger tips touching the lime plaster. Allow to begin to stiffen up. After 5-10 minutes apply another layer. Do this 2-4 times depending on the thickness of your layers. Burnish intensely with a yogurt lid cut into a circle, or other smooth plastic. After getting it very very smooth, and it begins to harden to the point where the yogurt lid is no longer effecting it (1-4 hours after burnishing, depending how wet your tadelakt mixture is) switch to a smooth stone. The stone should be a 7 or harder on the MOHS geological hardness scale with rounded edges to prevent gouging of your plaster. Burnish until it sparkles. Apply thin layer of soap dissolved in warm water with a paint brush and burnish with stone for another 10 minutes. There you have it. Good practice before you spend hours on a wall or bathtub or something that might fail.

Try to take one of Ryans workshops, or get him to teach in your area if there are enough people interested around your community. Good luck and let me know if I can answer any more questions.

I posted this on our Facebook page we are getting some answers there

Ryan Chivers Well... Tadelakt is basically simply a combination of lime, ( I use a good Type S) NHL 2.0 works too. and a crushed marble or limestone aggregate. The marble should be screened in such a way that the biggest pieces just pass a window screen and at least 15% is smaller than 200 mesh. The lime and marble should be mixed 50/50 by volume. The soap can be any simple vegetable based soap. Marius Fabre savon noir is the real deal. You can use " kiss My face" olive oil soap. So that s how to make it. As for to how to do successful tadelakt. Lots of practice!!

If you are on Facebook it is recommended that you join this group Talking Natural Homes

Ardilla Esch wrote:
The fats in the soap actually form a chemical complex with the lime in the layers of plaster. It isn't just a coating. So less mobile or non-soponified fats applied to the surface won't do the trick. It is important that the soap be applied after the plaster goes on the wall. If you mix the soap in with the plaster before applying the plaster you will not get good results. The soap does have to be applied before the plaster cures as well.

You shouldn't substitute for non-soponified fats either because that is important to the chemistry that forms the lime-fat complexes. If you tried to apply olive oil instead of olive oil soap - you get something altogether different (a softened, darkened plaster prone to sloughing and going rancid).

And that chemical complex is a soap. Specifically a calcium soap. The reason that lime is caustic to the skin, why it feel slippery to the touch, is that it is saponifying the oils in your skin. Lime is not as caustic as lye, hence the saponification takes longer and unless you cook it, it is not going to go to completion, which is why you get a plaster that is prone to going rancid.

Ancient people that had to use bear fat and burnt shells to make their plaster had to put up with the rancid smell, but in time, their softened, darkened plaster would cure some more, the unsaponified fat molecules would decompose and at least the plaster would be somewhat waterproof.

I ran across this webpage on Facebook. Tadelakt Instructions It has some good information on it.

Christian, that is a wonderful link to include here...I can't believe I left it off my list above. Great job adding!

Regards,

jay

i'm also on my way to tadelakt found this, quite useful i think - http://www.caneloproject.com/tadelakt-in-france/

Tadelakt, is one of stucco. It is a coating of lime water, shiny and waterproof. It can be used both indoors and outdoors.
i just use Moroccan Tadelakt for my bathroom, realy it's fantastic.

So much great information, but I didn't read about the actual reaction in a typical tadelakt which is; free calcium in the plaster reacts with soap to create calcium stearate aka soap scum, just like in your shower.

The real key here is application of the plaster must be super smooth in order to polish the soap scum evenly ensuring that the entire surface becomes waterproof.

To get this we first apply the lime plaster (I recommend some sort of hydraulic lime mix) with a wood float, then scuff out the high spots, apply the next coat with a steel trowel and burnish heavily. This second coat might be multiple coats in order to get the super smooth finish that you need. Then mix the soap into water and apply the bubbly stuff (keep whisking as you apply) with a big mason's brush. Burnish this with a steel trowel and then repeat the process using a good, hard smooth stone and repeat and repeat.

We sometimes mix soap into a final coat that has no aggregate only lime, color and soapy water, but not for a waterproof tadlakt only a highly polished wipeable surface.

All Blessings,
Bill

What part of the process makes the walls waterproof? The soap or oil at the end? Or are there ingredients in the lime plaster that create a water proof barrier? Thank you!

That is not the recipe