Any information with step by step instructions for panel prep for portable frescoes. Which materials are used before arrechio is applied? How many layers of arrechio before intonaco?
Nathan

This is an area where I am just about to resume my experiments. It is a system which has evolved from my experience with plaster and concrete. I am not interested in 100% historical accuracy - I am after a system which works - the panels must be lightweight as possible, safely shippable by U.P.S., stable forever in a light exterior environment, and the final intonaco layer must be the real thing.

Where I am at so far. Review elsewhere in this forum for missing details.
1) I cut out pieces of "hyrib" expanded metal lath to the rough sizes I like. On a flat bench, and/or piece of plastic, a mixture of about 1 part white cement, 3 parts clean sharp sand, is trowelled onto the lath, making sure it goes through all the holes of the mesh. If the mixture is to dry and stiff, you can add some lime putty to loosen it up. This layer is usually pigmented with inexpensive (compared to fresco) concrete colors (Davis is a good brand), I like a chocolate brown - so that color is mine, pick you own :p. The thickness is about 3/4" - now make sure the surface of the slabs is "raked" like scratched with a metal comb, quite coarsely, before the slab cures. Now cover the slabs with plastic, keep moist for at least three days, heat is OK, but not dryness. It takes 30 days to fully cure, but you can start painting after three days.

2) I run a loop of stainless steel aircraft cable through holes drilled in the slab with a small masonry bit drill. Clamp the cable with copper ferrules. The tools and supplies are available at a local "rigging" shop or sailboat shop. A special cable cutter and clamp pliers will be very handy

3) When you know you will be painting in a few days, select slab(s) from your pile and soak in water, at least overnight (one of the blow up kiddie pools could be handy). The slabs should be damp but not dripping wet, get some concrete bonder liquid and brush it on full strength to the areas you will be painting. The next layer is a modified intonaco, use a coarse and medium sand about 2 1/2 parts to one part lime putty and I also add white cement powder about 1/2 part. Trowel it on, again leave a rough surface, but not as rough as the previous layer.
4) These curing slabs are different from normal fresco because we can more easily control the cure. If kept away from air, the lime will not cure - the white cement will, just enough to stiffen up the putty. So these slabs you can keep around for at least a day or two, maybe much longer, as long as they are sealed with plastic wrap. When you are ready to paint and have time to watch the slabs, the final layer is a thin 1/8 to 1/4" layer of lime putty and fine white marble (or dolomite) sand approximately one to one mix. Trowel out smooth and you should have enough experience to know when to begin painting.

This is my defintion of portable panels. Diego Rivera's portable panels were 3" thick! I think this system could be used by both the professional artist, cranking out masterpieces on a daily basis, or for the part-timer. It may not be suitable for the first timer - its too hard to explain consistency and troweling and when the surface is ready to suck in pigment and when it is too late.

I realise that this may start more questions - but thats ok. Remember that I am learning too - but I did have some delamination problems with my first experiments. The batch prepared as above has been outside all winter (heavy exterior environment), the surfaces (not water glassed) degraded but these slabs are now strong enough that I can actually walk on them like a bridge.
I also wonder if the surfaces would have held up better if they were left a couple of years to cure, rather than a couple of months. Delamination is caused by different expansion ratios of the materials.

Please bear with the grammar

I use 3 different methods (one is yours Gary, modified though)

1) For Discover Fresco Workshops for Children introductory classes, presentations and "sample playing" 12X12 and 16X16 inch tiles are the most convenient for the following reasons:

a) Super Light (in fresco reference)
b) Enables you to go straight to the painting without missing much of the plaster part (most of it is "unconsumable" for the spectators, novice and kids anyway)
c) Gives an opportunity to walk virtually anybody through the steps of fresco painting without boring them to death.

setback - looks too easy.

8 parts sand 5 lime

2) For 2-day professional workshops and small frescoes I have adopted a modification of Gary's original method (details in student's forum) it really speeds up things since I need four panels for each student (do not worry, Gary, you get credit at every class).
This is perhaps a better choice for the museum - (I hope you will mention Gary and TrueFresco.com during the presentation)

3) For advanced Fresco Workshops and portable exhibition size frescoes, I use metal frames with earthquake resistant fastening system of my design the plastering methods are the same as above - they did it this way (plaster) for thousands of years and I do not see the reason to change.

About delamination - after 10+ years of my own and Ian's experiments and discussions/consultations with pro plasterers and especially after a few of the plasterers have attended my workshops and being third and forth generation plasterers had to straggle with the high calcium mortar (only thanks to Ian, he is an old English trained plasterer, they did not tell me to "go jump in the lake" before we understood the problem). I have come to a conclusion that the main reason for that is improper moisture control, wet mixes, thicker "topper" coats, faded knowledge of high calcium lime mortars and... (Gary, I am already ducking...) love of cement.
(more in student's forum)

lastly - the wall is plastered in the same way.

I know, Gary, we can not all "wear the same shoes" and perhaps your way could be much more outdoor resistant.

(Nathan & Gary, check your private message inboxes for my message)

You make some very valid points.

I wanted to mention that I only experienced delamination in panels that had been left outside, in the rain, in the sun, in the snow and in the frost. I wanted to see what the worst would happen in Vancouver climate. My sgraffito in white concrete & lime is as strong and clear as the day I made it - for signage it is actually more durable than alkyd exterior paints.

I agree that your painting time is reduced because of the lower volume of fresh lime putty - but time has never been my enemy on a 1 metre sq. panel. 3-4 hours at least. The enemy unique to fresco painting is interuptions and distractions!

The concrete bonder does work, bonding concrete to concrete is an everyday problem in the construction industry. Make sure the acrylic doesn't work its way to the surface, so this requires a firm and sure hand when trowelling. Make sure you "scratch" the surface before coats- there is actually a special plasterers tool for this

Most of my fresco work has been done on old Italian walls, so my panel work has been limited to terracotta tiles. I've seen tiles laid inside wooden boxes(1" thick), chicken wire was fastened over this to hold 1 layer of arrechio. The intonaco was applied over this.

The panels seemed to hold up pretty well. Is this overly simplistic? Does it last? My presentation is only 2 hours, so most of my fresco will be pre-finished. I'll demonstrate how to apply a giornata on an unfinished bit (something interesting like a face or an angel wing). I'll mix the lime and show how to dovetail the previous giornata in order to fit the new section. After I paint on the wet plaster, I'll do some secco work to hide giornata divisions that may stand out, or other decorative embelishments. Egg tempura will probably be the best, as ilia suggested.( I know a cool secco technique using milk... let me know if you want to hear about it later... I've already digressed too much from panel painting....)

So... panel techniques. Again my experience is limited so bear with me. Gary, what your talking about sounds pretty involved and heavy duty. I don't know about hyrib metal laith, stainless steel aircraft cable, or copper ferrules, so it's hard for me to completely understand your process. I'm not going larger than 30x40" for this demo.... what size are your panels? Is it simply more durable for shipment, longevity, etc.? It sounds like you and ilia do this alot and it is very practical for you.
Also, the conservationists who taught me in Florence and the restoration supply companies (PHASE,and Zecchi) told me that cement and fresco do not agree. Humidity carries salt deposits through the cement too large to pass through the intonaco. The salt remains and destroys the matrix of the fresco from the inside, causing the surface to flake, fade and/or discolor.
I know these are panels, and natural moisture may not apply here, but does the wetness in the cement, arrechio, or intonaco ever affect your process?

Nathan

oh yeah, I'll be sure to mention truefresco.com at the presentation, as well as you guys.
Gary, if you have pictures of your process, I might understand it better being a visual person and all.
Thanks, nathan

I am sorry Nathan, I read your post in the context of the first post - that you were looking for portable panels. This is at the core of reintroducing fresco technique to Canada & U.S.A. Unlike Mexico, there is no real tradition of murals here and even then 99.9% of murals today will be in acrylic or enamel sign paints. So the challenge is/has been to come up with a fresco technique on smaller, easier to manage, easier to market panels. A panel of precast concrete or well cured layers of lime putty, pozzolan and sand would be extremely heavy without reinforcement. It would have to be two or three inches in thickness - a panel 24" by24" by 2" would weigh over 50 lbs, 25 kilos.

The ferrocement panel I decribe would weigh about 10 lbs, 14 with all the putty. The effect is have the white putty on a colored slab, and the slab is irregular cut - it looks like someone went to your country, chiselled a fresco off a wall, and smuggled it back home! This also allows me to paint irregular size sections, not "boxed in" to a visual square.

So, of course a buon fresco on a ancient or new stone built wall is the way to go. Here, nearly all walls are concrete and steel, or brick and wood. People move all the time, if a building or home lasts twenty five years it is most often torn down and rebuilt. Also,too many people want their art from galleries and festivals - to be seen buying art is important to them. These same people often buy homes, or I should say houses, as investments. An original work of art which becomes part of the architecture can be a very valuable thing to leave behind, or it could also be a stumbling block to reselling the house. Ours is a highly portable society, with very little experience in arts/culture - we want demand instant gratification in nearly every facet of our life.

I do have some standalone pieces, but generally I am doing reproductions of the classics, from around the world, in the scale they were originally painted - so I choose 'fragments' of larger frescos. A 24" by 24" "fragment" panel should sell for about $300 - $500. So I have an educational and also businesslike approach - not fine art. The fact that I am reproducing, also gives me the right to repaint and resell the same fragment theme. So this can be quite profitable - until I get tired of painting the same damn fragment each time just because thats what people want. I know, for example, I could sell a "fragment" of the two hands touching in the creation scene, Sistine chapel, about 500 times.

As far as concrete leaching salts (efflorescence) this is a problem solved many years ago in the industry, the salts are not a problem today. They are a sign of bad curing practises and inferior materials.

>I know
>a cool secco technique using milk... let me know
>if you want to hear about it later...
>

That would be great! Start a separate topic "Secco Fresco" and we can get a good bunch of articles in it!