Greetings,

I am very much an amateur in the art of fresco, having jumped into it headfirst last summer when I plastered our entire basement armed with no more knowledge than I could gather from combing the internet (ah, if only these forums had been around then!) Now I am moving up in the world - I am now plastering and frescoing the front staircase of our house.

Now, this house was built in 1779, and has settled a bit since. This results in the plaster along the staircase wall buckling in places - picking up giant cracks and pulling away from the wall. It looks as if it has been replastered once since the colonial era, but what I think may be the original plaster is still visible underneath. It's a sort of tan-brown,quite rough, with what appear to be hairs mixed in it. Maybe there was also a top coat, too - there appears to me more than one layer in the chips that have pulled away.

And now for my questions! Does anyone know anything about the sorts of plaster that would have been used in colonial America (the Connecticut River valley region, if you want specifics). Would they be suitable for fresco?
What steps ought to be taken to restore the wall?

I found an old Essex County recipe for a lime finish designed for whitewash, which included rice flour and common glue besides the lime and hot water. The book in which I found it (American Decorative Wall Painting 1700-1850) when speaking of fresco itself, says, tantalisingly, that "directions for this process are found in many of the old English recipe books, but this method does not seem to have been used by the itinerant decorators whose work we are considering." And that's all it says about fresco. Does anyone know what those directions might have been, or if they differed substantially from the ones available today?

Also another question, not really relating to the colonial era: last year, when I was experimenting with fresco in the basement, I tried something called "autoclaved finish lime". It said to use immediately if mixing by machine, and I did. The paint went onto it very nicely, but later the plaster began to crack. Not too seriously, fortunately - indeed, now the fresco has the antique look that has been sought with so much labor by other painters. But I was wondering - what does "autoclaved" mean, and is it really suitable for fresco, and if so, what are the proper preparation steps? On the back of the package it said to mix with gauging plaster, but I do not think that the instuctions were directed towards one who wishes to create a fresco. I've never heard gauging plaster mentioned in all my reading on the subject of fresco plastering; what is it?

Thanks for the wonderful forum,

Katherine Nehring

Hi Katherine!

Plaster for fresco consists of 5 parts of lime putty and 8 parts of fine river sand.

We have several topics in the Cafe of fresco plaster and how to,
please read them - look for Gary's posts, especialy on how to prepare lime putty from regular hydrated lime.

What gets you confused is the word "fresco" in the adwertisings.
They just use it as a "hot" word. At the moment NONE of the merchants in US big or small has anything for fresco, they might have basic ingredients though but they would have no idea on how to use them for fresco.

Basic ingredients

river sand (sea sand has salts - bad)
lime putty (slaked quick lime)
natural pigments (oxhides and mineral pigments only)
water
brushes
walls or panels
trowels
You

Post your questions we will be glad to answer!

concider taking our workshop
http://www.truefresco.com/workshop

Good luck with your repairs Katherine.

You have raised many questions.

The autoclaved lime I have never used, but I have heard that it is very strong in plasters and mortars, and, as you write, it is usable immediately. The gauging plaster is a US Gypsum product available from specialty suppliers. If you are really interested in becoming a plasterer you will have to read some books, take some courses, and hang out with some experts. Be forewarned that this is the most physically demanding of all the construction trades but the most creatively rewarding - yes even more than painting. You might have to get a quote for your cracks, this is a job requiring experience. I just fixed extensive cracking in a 1912 building, you never know what you will find underneath the top layer.

You will have problems at 100% lime, because the lime will shrink slightly - this is why we add sand for fresco, or gypsum plaster for decoration (gypsum slightly expands). My own mix for fresco is often high calcite lime putty, white dolomite/marble sand (of various sizes) and white cement. This is tricky because white cement also shrinks. I am also using concrete bonder, a type of glue from stucco suppliers, it is used to make sure the layers stick together and onto metal lath. I was worried that it might interfere with water flow between the layers, but I have found no difference in side by side tests. I try to make sure that the bonder is limited to the surface, that it does not become mixed in the general putty. I am interested in exterior frescoes, that can go out in the gardens in summertime, under cover for the winter, so I am more concerned with long term wear. It is amazing how tightly the pigment bonds to the lime - I have had some painted scraps underwater (!!!) for three months now and the colors do not wash out and the cured sand/putty (no cement in this one) still stays together - amazing. I think the biggest killer of outdoor fresco will be frost - freeze thaw damage.

A lime by itself would have to applied like a paint over many years - this is like the Greek villages where 1000's of years of an annual lime paint have built up a hard thick shell.

To all those who asked for scans of lime paint recipes, please bear with me, my scanner is down. I might just send it to Ilia in PDF format, via email, and let him figure how to post it. I have many more old recipes too.