This is the fresco index.
I have it in my mind to do a fresco. SteveL of the Painting on Location with Color Forum, in the Fresco Category asked if the Real Color Wheel would work in fresco. This fresco set of tests will show you how to make a buon fresco and use the RCW. All pigments show their lime test results.
What I've learned about making a fresco panel and painting it.
Today I made the outside studio area to paint fresco here at my friend Piero's Villa in Kaupo.
I mixed a 20 lb. bag of hydrated lime in 2 five gallon buckets, sifted and stirred it up real well and put a top on them. In two months there was 4 inches of lime water on top and the lime was just as thick as the 2 year old lime.
I still have the 2 year old slaked lime to compare this lime to. SteveL has 9 year old lime.
In some prepared mortar I added 25% lime and enough black pigment to give me a black base coat. While it was drying I scratched in some deep texture lines to give the new lime something to get a good hold on. I'll scrub it good and paint on some casein where I'll be putting the next layer. I plan on layering on a few wet lime coats to paint on and leaving a decorative boarder black.
There is a comparatively new product out now, it's an acrylic based adhesive/bonding agent. Use it between layers for a tighter bond.
Here's a little about lime.. It's the weakest part of your mortar, sand is strength. Rough crushed sand, limestone, lava or marble is better than smooth sand. Three sand to one lime is stronger than 1:1 sand to lime. Mortar not locked down will shrink, a 1/8 inch thick layer of mortar on a 12"x12" glass will shrink a fat 1/4 inch. That amount of mortar is a 2.5 inch square, one pound of mortar, and should be just firm enough to form one tile. I think the best mortar I've made was with what is called crushed white marble from the cement dealers, it's really crushed limestone and it's used by the pool building trade. I sifted it with a common strainer, not the fine flour strainer I used for sifting the lime into the store bought morter, use the next larger size. The larger grit sizes I used in the brown coat / rough coat / first layer. For fresco panels only two coats are needed, and the first coat should be dry before applying the thin intonico (less than 1/8th inch) coat or top layer.
The reason for using white limestone in the pit lime is big. Seeing the colors used clearly is very important, so you need a white base. Using lime paste and lime pigment as white is Ok but not the greatest. I like WYSIWYG. Use titanium white instead, and don't paint with washes. Lighten your tints with titanium white not limewater. True, all colors lighten as the fresco dries but it's really not that much. It's about the same as wet and dry watercolors, maybe twice as much if you use washes instead of mixed tints. Mixed tints change less than watercolors do, so it's not much.
Everything I'm saying here is backed up with photographs.
Lime water does not seem to dry white as I first thought. I made 4 batches of lime to slake, two small ones from a bag of hydrated high calcium lime sifted and mixed until it was smooth and one from the lime sifted into the water. The third sample of lime water came from lime that had slaked for more then two years. All slaked lime is also called pit lime.
None of the lime water tested turned white after drying on wood, metal or my black pigmented lime mortar base coat. Everything I read said it should but it didn't. As long as the water is clear and has a floating crust of carbonate I know it's good.
Fresco on Location
This first photo is the fresco right after it was painted, the second photograph shows how the colors changed in three days. The sides were plastered also and painted in a continuation of the scene, it's one inch thick total.
Three days later it cracked, because the top dried out before the insides. Perhaps I should have let the lower coats dry first which I'll do on the Little Bella fresco. Notice the color changes in the ultramarine blues at the tops of both mountains. The left mountain was mixed with ultramarine blue and burnt sienna to make a green dark. The next fresco will be using cobalt blue deep instead of ultramarine light because I use that hue to darken burnt sienna and orange. I've since learned that cobalt blue deep turns a dark blue gray in fresco but not in secco.
Also the Ultramarine's turn white when mixed into the mortar but not when painted on as fresco.
Here is the lime in a jar with pigments tests. Ultramarine is very safe in secco only, glue the secco pigment with casein medium or egg.
Here is the picture of the cracks, since it was still moist and pliable, I pressed out the cracks and ruined it.
Today Jan. 9th, 2004, I did the same painting test on the same type of brick tile with
Three Weeks later, the cobalt blue deep pigment in the sky turned gray and the
Kaupo from Johnny's place.
I took a bucket of 1:1 sand and lime plus a 1/2 inch thick brick with the first rough coat already dry. Plus my pigments, lime water, a #8 squirrel hair brush and trowel on location. Applying the top coat and painting took a hour and ten minutes. The painting took an hour, 01-15-04.
Here it is 16 days later. All thinly applied colors appear lighter mainly because the underlying lime changed from translucent to opaque white, changing the darker color of the sand. The purple became more purple. My next mural will have white marble instead of sand mixed into the lime. That way I think I will be able to see the final colors as I paint. Later I discovered that using titanium white lime paste tints is better, a lot better.
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