I ran across a website www.dirtcheapbuilder.com which is an excellent resource for building with traditional and green materials. Their bookshop is quite extensive, I have (a photocopy)the back issues of "The California Plasterer" from the 1930's and it is the most comprehensive source as to the history of plaster and lime, including excellent sections on the frescoes of Italy and India.

Please also note that my new email address is gary@mozaya.com - I haven't had the time to figure out how to change it on this user profile.

Gary & Community:
good morning! I am new to this site, as of 2 minutes ago. I am in southern Arizona, U.S.A.

I am interested if in the book on California lime plaster history if there is any information about sealing the plaster.

I have finished the first coat of lime plaster in a shower stall that is constructed of 2x6 wood frame with straw-earth in-fill between the studs. Definitely learning about its requirements as I go.

ONe of my teachers (Bill Steen) gave me the instructions for this process, though, he didn't give me the sealing technique, told me to wait until I was done with the final coat and finished painting and then he'd pass on his technique. Unfortunately, he's now off teaching in rural Mexico I believe, and not reachable.

I want to begin the second coat tomorrow morning, and I'm desperately searching for information about a safe and sound sealer. I realize I may be doing some repair work down the road, with all the splashing of water on the surfaces. I accept that. The shower stall I used up at my teacher's place a few months back, is beautifully frescoed, with minor softening in certain areas (the soap holder that is sculpted from the wall) that collect more water.

Do you have any recommendation(s) of what I should use to make the surface more repellent to water?

(Will have information to contribute to this forum on what I will and what I won't do on the next bathroom project down the road a few months...another earthen-straw project.)

thank you & community for any advice,
Margo

Welcome Margo!

You are in luck! Gary just got back from Mexico and has acsess to computer. So if he will not reply in a day or two. Do not hesitate to send him an email - use the email icon here.

Also use subscibe to topic function to get automated emails when someone replies to your posts/forums

Good luck and keep us updated!

<<<copy of reply to forum>>>

There should be no panic with the lime plaster - thats one of the problems with it in modern construction, it needs lots of time to absorb the carbon dioxide from the air, when you seal it you stop or least slow down the cure.

Some old time books advise waiting up to year before painting or sealing the plaster. The other problem is that if it is still damp, the alkilinity will effect many modern paints.

The best solution, if you are building a "300 year old" house (designed to stand the test of time - somewhat unusual in Canada and USA), is to make
sure the whole structure can pass moisture somehow - instead of sealing you put on something which makes it easier to clean (soap scum, fingerprints,etc.) without completely stopping the air and moisture. There are many strategies. The ancients would use beeswax, heated onto the surface and then burnished out. They might also use olive oil, which reacts with fresh lime
to form an olive oil soap. What I recommend, and has stood the test of at least 100 years, is a type of "water glass" called potassium silicate (kaosil). This is not the sodium silicate water glass. The problem is that it is available in huge, incredibly cheap quantities or in small, expensive quantities. To see how this works, checkout the website
www.keimmineralcoatings.com. I have had excellent result waterproofing fresco with this solution, and you can mix in your fresco pigments and actually paint concrete and lime plaster with it.

All these solutions are difficult to advise because so much is an organic process, a skill which comes with age and experience, difficult to predict what will happen without seeing the job. Sort of like the old water witchers, or the old pros which can find a leak in a roof many yards away from where everybody thought it was.

Sometimes, like old plaster and old wood, the wear and tear actually adds a beautiful patina to a piece, which modern plastics, paints or glass never
seems to develop. This is the best goal in design.

Lime washes would have to be replaced constantly in a shower stall.

Sorry, I have written this quickly. No problem at all if you have more
questions.\

Gary Waller

<<end of message>>

Gary:
thank you for your detailed reply!

(and for confirming that this is a mind-soulfull process)

I had trouble getting onto that link you gave, though found many other links for POTASSIUM SILICATES and its a little overwhelming figuring out where to go.

I'll look to see if I can find a source locally in the Phoenix area.

Being optimistic that I do find a local source within a week or so, do you have a recipe that you prefer to use? If so, can you share that with me, the proportions of ingredients, etc.? I am very appreciative of anything you can contribute to my domestic project. I do enjoy the physical part of plastering the walls, sculpting them to my sensibility, and I'm very much looking forward to painting the colors of my childrens' and my own dreams on them as well, in the weeks to come, thanks!

all the best,

I lucked out with a sympathetic salesman, who sent a 'free evaluation sample' - about five gallons! So you have to mix it about one part silicate to about three parts water - so I have a big supply. You have to mix in water because it carries the silicate into the substrate. This is basically 'liquid silica sand' which reforms into very fine silica crystals. There is a book called Painters Handbook by Mark Gottsbergen, it has a long section on fresco and he tries out all the other silicates except potassium. I recommend this book though - you should be able to get it from a library in Phoenix.

This silicate is used extensively to make high strength concrete. There are small quantities available from kremer-pigmente.com It turns out that potassium silicate is the solution to the 'lost' sound of stradovarias violins.

It is remarkable stuff, has no smell, but is high alkaline. The wierdest discovery was when I was mulling pigments and silicate on a piece of frosted glass. Some of it dried overnight and it had bonded to the glass (another form of silica sand) so hard that I could only sand it off.

The key is apply enough to protect the wall but not so much that you get a glossy buildup - this, again is an experience thang.

sorry on the link

Try http://www.keimmineralsystems.com

Another thought - on the Keim website check under waterproofing - there are two other products which also would work, one is based on a type of silicone and is used extensivelly in the tile industry to waterproof and as a stain resist for grout. The water splashed on it beads up and runs away. You have to renew it every once in a while.

Gary:
You've been very generous.

Thought I had a local link for the potassium silicate-- that didn't pan out after all . . . .

I checked out the Keim web site you provided, and thanks for that. Let's see where I get....

thanks!