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Painting on Location
by Donald A. Jusko

Little Salmon River, Buon Fresco Preparation

Texas, Mexico, NY, #51

82"x155' = 6'10"x13'

Texas, Mexico, New York. I arrived 5-25-4 and unpacked. The actual wall is 82"x155" and ready for some cement board, lath, a rough scratch coat, a middle brown coat and a top intonaco coat. The bottom 3' of the wall will be oak. If I paint three square feet per day, equal to a 18"x54", that's a month's work. I still don't know what I'm going to paint as subject matter.

Back yard view

Geese by the river

This is the 82"x155" wall we will attach the sub board and metal lath on to.

Bare fresco wall

This is my working space setup, all safely shipped here for $425 in one week. That plus thirteen five gallon full buckets. 4 slaked lime, 2 large sand, 2 medium sand, 2 small white sand, 2 white cement, 1 dry lime.

fresco setup space

This is the view out the back window. Beautiful, with the Little Salmon River just a stones through away. Two days later the cement backing board and lath were up. That's John Loyer helping me, he owns this great 200 year old house in little Texas, Mexico, New York. It's half of a mile from Lake Ontairo.

fresco setup space

Lath Attached with nails into the frame and stainless steel staples.
fresco setup space

Lath Detail
Soak the previous mortar's dry edge before adding new mortar. The larger the mural, the larger the surrounding wet area should be. Lower areas of the mural stay wet longer. Attached mortar sets and dries faster, so paint your edges first.
lath rough wet edge

Here are the 4x8 test tiles.
Top left, Floated, 1 medium sand, 1 small sand, 2 lime, alum (dry size, about 2 grains of rice). 1:2. This was a test to see if the small sand could be used in the 2nd coat, it can't, there is not enough grab unless you float it really rough.
Top right, a rough coat with intonaco on the top half as faux marble. The floated rough coat is 70% lime and 30% white cement, with 1 rough sand and 1 medium sand. The intonaco is, 1:1 lime and small sand, the pigment is indanthrone blue. These I will use for the fresco.
Bottom left, 70% lime, 30% white cement, 1 large sand, 1 medium sand. This seems to make a hard enough first Rough coat.
Bottom right, 1 lime, 2 medium sand, alum. This will be my Brown 2nd coat. It's a harder mortar with the alum added and will still emit calcium carbonate to the surface.

Mortar Tests
fresco mortar tests

5-28-4, the cartoon paper is up on this scale fresco and I'm drawing on it in chalk. There is a head molding and foot board of marble, a ventilation vent and two electrical plugins to contend with. We decided on a 1 inch white tile as a protective bumper. That is going to be the painted porch railing and the gate's railing, all across the mural. Aqua-Net hair spray is a good fixative for pastel on paper.

5-29-4 I completely changed my mind about the subject of the mural. Below the ceramic tile chair bumper guard I will make a faux marble base. Above this will be a river painting.
The fresco wall has been gridded in 1 foot squares with a wax based pencil.

5-30-4, I'm painting 'to scale' sized acrylics, in the morning and afternoon. One from 10 in the morning to 12 and one from 1:30 to 5 in the afternoon. Both on a 15x22, 1/4 inch plywood with cloth glued on it.

5-30-4, The top one I drew out with charcoal, the second with big washes of the local highlight color. With this technique you start with the big light areas and jump to the big darks. At the end it's very accurate. I'll use this technique on the fresco if I try to do the whole top 2/3 painting in one day. That's going to be some big brushes and sponges. The first technique lends itself to giornate cuts in the fresco to paint smaller sections each day. Deep down I want to use the second technique.

Test, baking soda hardens the skin of lime just like alum. Dentist tooth molds are cast with this baking soda salt. Baking soda seems to make the skin harder by moving the lime to the outside of the form. It did nothing about making the inside hard, in fact I think it was softer. Alum on the other hand made the mortar harder throughout.

White cement is used in pool building and it holds water a long time. It has no acrylic additives, only white pigment. My test was with Quick-set, which has an acrylic additive. Quick-set stuck to shiny marble but the white cement would not.

6-5-4, Saterday early afternoon. A very full day. The morning painting of the river was from 9 AM to 11 AM, lunch and lay the rough coat mortar. 16 oz. cup = 1 part.
3 parts lime = 66%, 2 parts white cement = 33%. That is a total of 5 parts.
5 parts of large sand and 5 medium sand is 10 parts. That's 1:2 mortar with a cement 2:3 lime.
it takes 2 hours to lay a 2.5x7 foot section. I'm almost half way finished with the Rough or Arriccio coat. At this rate I have six days to finish two scaled paintings, chose one for the fresco and re-attach the cartoon grid, transfer the paintings pattern outlines. That should take a day, the Brown coat should be dry and ready for the Intonaco.
(Eighteen days later I finished the morning painting.)

6-6-4, I worked on the morning painting, the previous url, scaled acrylic painting.
Mixed up another batch of Rough mortar, 5 large sand, 5 medium sand, 3 lime paste, 2 white cement, 1.5 water. That equals a 1:1 mortar. Mix the dry first, then add the wet lime, then the water.

Making Rough Coat Mortar Large Mural
making fresco Rough coat

I laid another 2.5 foot wide top to bottom section of Rough coat, my wrist hurts. I sprayed the old edges good with lime water before adding the new mortar and after floating the surface to work the mortar into the lath, I went over everything new with a wet sponge and feathered in the edge. Than I did something on my own, I can only call it shaving. I did it to level it closer to the level of the lath. It seems the 3 foot drop cloth is wide enough to contain all messes. Later I installed a white Tyvek building liner, Nice, light, water proof. Later, after I had worn it out, I relaid it and added another layer of clear plastic 5 feet wide, the same plastic that is to be my cartoon.

6-8-4, Tuesday morning, the acrylic painting session went well. The alcohol and pigment painting test are drying from yesterday.
I've been playing with color on the dry sections of the Rough coat, with alcohol and limewater. The alcohol makes the Thalo blue a cyan hue, water makes it more blue. That's on wet or dry mortar. Alcohol keeps it suspended finer. The pigment itself wants to stick to itself and will clump. It should be reground in limewater with the palette knife for each large stroke.

TIP: Thalo green is much harder to keep suspended, Thalo blue and transparent Indian yellow will make a more varied green that will darken nicely with transparent magenta PR122 or PR202. But, if you need a lot of that particular hue add lemon yellow. It suspends better.

I made another section of the Rough coat and painted a full color wheel with these colors and lime water. Zecchi Indian Yellow nickel complex, D.S. Quin Red PV19, D.S. Quin violet PV19, Thalo Blue, it's a perfect color wheel. Geez that Pigment Color Chart is messed up. It's just not logical to have a color on each side of magenta that both have the same Pigment Color Number.
That's also the same hue PV19 that was not lime proof from Zecchi, Daniel Smith's PV19 is lime proof. Zecchi's ultramarine blue was not lime proof either, Senopia's is.

Something is wrong with the current Pigment Color System, red and violet shouldn't be the same Pigment Color Number. Cadmium red is PR108 from red to brown. You just can't tell what color you have from the number. This is good only if you are a chemist.
This Pigment Color System labels by the pigment's chemical composition not the pigment's color. Other systems label the dried chip color, and it's not inclusive of any number of chemical pigment colors involved, and still other's follow the RGB/YMC color wheel from yellow down to black, matching the black subtractive light's photographic color to the pigment black.

Pigments are additive, the primary triad of three transparent colors mix a dark without black pigment.
The colors should be labeled as my RCW labels them, than each color section would have different pigments assigned to it. If two pigments were the same anywhere on a smear test the terms: transparent, translucent and opaque would be in the name, along with the chemicals involved.

The lightest yellows, hansa, cad lemon, and lemon yellow chromate would be 36RCW#01.00.05, the darkest burnt umber would be 36RCW#01.10.09. (color 01 to 36, value 00 to 10, cool-warm 01 to 09)
Yellow-green would be 36RCW#36.00.05, Raw umber's dark is 36RCW#01.10.01.
Colors are numbered from one to thirty six. The light to dark values of each color number from 00 to 10. They match each colors elements in crystals as they get darker.

Here is what tonight's colors look like.
Five days is all it takes to tell if it's lime safe but I know it's alright, I tested it. fresco8jarlimetests.htm

Brown Coat Large Mural

Tonight, after the afternoon painting session I wet the mural and laid the first twenty eight square feet of Brown coat on the 82x155 mural. Ten sixteen ounce cups of medium sand, five cups of wet lime, 1.3 cups of water. Three and a half hours labor, after using the float trowel I gave it the once over with a sponge to make it a full rough. I'm going to get a sponge trowel for my next mural. One section down, three to go.
It was a good choice to use the medium grit sand on the Brown coat, since I can't have my favorite, crushed limestone. The medium sand coat made good even depressions, great for holding the next layer. I can trowel the brown as thin as possible and still get a good 3/32nd's of an inch thickness. It's the intonaco that has the big thickness variance possible. I would like to use some kind of level for it but I won't.

The next day, Saturday, June 12th. Second section brown coat, adding 1/4 teaspoon alum, I forgot in the first section.
Trowled in 6" strips ceiling to floor. The whole four foot strip was pre-wet 2 hours before and up to the time of toweling. Four foot by seven foot, 5:30 hours including clean-up.
6-11-4, Sunday, The next morning I decided to work this end of the mural instead of painting as they are so close to being finished.
I'm wetting both the small panel and the large mural. I plan on finishing the Brown coat.

Wet wall first

I had to make a drastic change, I'm running out of medium sand and can't get more. The new Brown coat mix is 2 medium sand, 8 small sand, 6 wet lime, 1.25 water. It is a lot harder to get a grabbing surface, and it's very important to keep the wall wet. Sixteen square feet = 2 medium sand, 2 small sand, 3/4 water, 1/8th teaspoon alum. 5:00 finished the mural's Brown coat. Well done! Now it just has to set untouched for two days. My wrists hurt.

compare acrylic grid

If you don't lay the intonaco while the brown coat is still in it's wet setting stages, you must remove the dried extra lime and calcium carbonate from the surface and expose the sand, like the top third in the photo below. Any dry strong scrub brush will do, this one had a long handle and gave good leverage. This is an important step if you are working on ceilings.
This is 1:2 mortar, that's a lot less lime in it then an intonaco mortar.

Remove calcium carbonate

Testing the RCW color wheel and pigments

This is a test with lime water medium on lime mortar, 3 colors.

Primary color test, water

This is a test with alcohol medium, 3 colors. The only way to get a cyan hue is with alcohol as the medium, lime water makes a more blue color. D.S quinacridone PR202 magenta can be made with D.S. PV19 quinacridone red and PR122 quinacridone violet, quinacridone red is on the warm side for your only magenta but is still able to make reds and neutral darks with green to turquoise. It will also make an exceptable blue but not as good as quinacridone violet or quinacridone magenta will.
The colors will show up a lot better when the mortar dries. Notice how you can see the titanium white tint in the PV19 warm magenta against the gray mortar. The difference would not be noticeable on white crushed limestone mortar, which is a lot whiter. PY108 Nickel Complex transparent yellow Br/S and PB15 cyan round out the palette shown.
This mural will be made with the white sand available here on the East Coast, it's not as white as limestone but better than brown sand.

Primary color test, water

Faux Marble Base of Mural
I'm going to use white cement in with lime 1:1 for strength. There is no problem, my colors are lime safe and sulfur safe.
Into the mortar of 1 lime, 1 white cement and 2 small white sand. I'll add the color with lime water and cover it with a layer of cera colla water wax and buff it up. That's the way the Egyptians did it.

6-21-4, laid the first giornate of the faux marble base on the 12x24. I added indanthrone blue to the mortar. On the 82x155 mural I laid it 1/4 inch thick, 1 lime, 1 white cement, 2 small white sand, 2.5 water. I left it pure white, added color will be in secco, than wax cera colla as a gloss finish and binder for the pigment.
It's pure white. 2.5 water. Time: 3 hours 15 minutes. That's not counting two hours of wetting the wall before making the mortar.

6-22-4, It's raining this morning, I'll lay another section of intonaco on the faux base. 3:3:6:2.5. Finished, 1 hour forty five minutes. Plus wet-down 2 hours and 1/2 hour cleanup.
Now I have a 1/4" X 34" X 29" white section of white marble on each end.

first faux giornate

6-29-4, We decided this bottom area would be oak wood instead of fresco. The area needs some protection.

Small Test, big answer

6-17-4, Since I have been removing dry intonaco from my scale model I realize just how soft lime is. I wish I could test and scrape a little off a 10 and a 100 year old fresco. Just to see how hard the intonaco it was. I believe the crust is very hard and brittle, the inside is easy to turn to dust, it just seems like I have already done it because I remember my surprise popping through the shiny crust.
That thought provoked this test. The main reason one didn't use gypsum in wall murals is because the sulfur changed the colors and had no transparent carbonate crust. Today we have colors that don't change in lime or sulfur.

I'm going to use white cement in the intonaco mortar, maybe. I'll make a giornate area on the 12x24 scale model first.

(A, lower tile) 10:15 tile #1, 3"x8", 6-17-4, left side 1/8th thick, white cement 1:1 small white sand. Top = alcohol medium, I put a stroke of color with alcohol and color. The alcohol floated because it could not absorb yet, too much unabsorbed water. It left the surrounding surface shiny and the colored stroke matt. Alcohol and water only mix up to a point.
3:00 and the cement is still painting and absorbing immediately, perfect, and the shiny area is very shiny.
11:30, same tile, right side 1/4 to 3/8 thick, lime 1, white cement 1, sand 2, = 1:1. I made this too water soft. 12:00 still wet shiny, 2:45 both sides are set, cement is a little harder. Paint was applied every 15 minutes or so.
Two days later, the 3/8th thickness didn't crack. This is my faux marble mural mortar.Two months later, The thin white cement on the left did not stick to the tile. Regular cement would have stuck. Lime must be added to the white cement as the glue, 50/50 worked fine.
5:30 Finished
6:15, This right side is almost as hard as the 100% cement side. I'll check to see which gets the better gloss. Two days later they both looked the same. The cement side is the hardest.

Tile A and E

6-22-4, (E upper tile) tile #2, five days later I washed the upper white lime 1:1 sand tile (E). It's all good news. The 1/4 inch thick mortar did not crack, the lime I use on Maui would have cracked anything over 1/8 inch cracked. What I learned: Three hours after laying the intonaco it was still a little soft, in four hours crust was forming. This is when it should be re-troweled to paint with an even absorption. I painted on the tile for an hour and a half, no new crust formed and I sure I could have painted two more hours or more. It's not as hard as as the tile (A) which is white cement and sand on one side and 1 lime, 1 white cement and 1 sand on the other. All the colors are absorbed and permanent. The 5:00 line of copy with Sinopia ultramarine blue for fresco absorbed well where the lime crust allowed it to be absorbed.

6-19-4, Here is the tile (A) cement 1:1 sand. Washed two days later.

Tile A washed

6-22-4, Here is the tile (E) lime 1:1 sand. Washed five days later.

Tile E washed

(B) 6-17-4, 1, 8"x8", tile (photo). 1 cement 1 small sand. 50/50 water/additive instead of just water. Covered with alcohol after adding pigments and leveling. Next day, it shines in places, very hard.

8x8 tile

(C) 6-17-4, 1, 3"x8" tile (same photo). 1 cement, 1 sand, (2nd small area =) 1 added lime. Sprayed with alcohol after adding pigments and leveling. Sprayed with alcohol. = Next day, it is strong, white and shiny. The alcohol spray wasn't necessary.
(D) 6-17-4, 1b, 3"x8"-tile (no photo). 2 white cement, 1 small sand. No additive. Twice as much cement as sand made a hard smoother surface. This will make a good faux marble surface.
(D) 6-16-4, I painted a pigment on the dry tile with acrylic cement binder, it soaked in well and is permanent with a shine.

(F) 6-17-6, 1/4", 3"X8" tile (same photo), 2 cement 1 sand, made with alcohol, not water. Two days later I could not tell the difference between using alcohol or water made cement. Cement without lime does not shine.
I just cant seem to get the shine I got on cement with a line of color that spread and bled out shine while the color was dull. 6-21-4, On this dry tile F I painted with acrylic binder and indanthrone blue. It absorbed very well and bonded. A gloss can also be painted with this acrylic cement additive.

Related Information

Here is a link in the chemistry section, RCW Color Course - Pigments, Chemistry. final.htm#CHEMICAL,-CHEMISTRY That's where this info comes from.

Boric acid is a very mild acid, as is acetic acid.
Carbonates and sulfides of metals are sensitive to mineral acids. Acid vapors and weak acids bleach lapis lazuli and syn. ultramarine blue, a colloidal sulfur. Acid liberates hydrogen ions, an electrically unbalanced or charged atom, Hydrochloric acid is violently caustic on metals.
Sulfuric acid is weaker than hydrochloric acid.

Alkali or base, is caustic and reactive, sodium hydroxide is caustic soda or lye, both lye and ammonia are strong alkalis. Alkali yields to hydroxyl [OH] ions, an acid.
Sal soda is a sodium carbonate or washing soda or soda ash, it's weaker but it will still dissolve wool and react with oils, fats and wax.
Sodium bicarbonate or sodium acid carbonate is baking soda, the dry mix of alkali and acid neutralize each other when they are hydrated, and carbon dioxide is set free. Borax is sodium tetraborate, a mild alkaline salt that's used as a flux with glass and a lime setting and hardener for casting molds with hydrated lime.

ALUM- Alkali. A double sulfate of aluminum and potassium crystal, a 5% solution will harden hide glue, gelatin and all proteins. It makes gypsum and calcium hard. Alum is a mortar for dyeing textiles. It's an astringent. Brown beeswax can be whitened by boiling it in alum water.

Borax, like alum, is an alkali, in ancient day's it was called "tin-cal", a Chinese word. Borax is found in landlocked lakes in Tibet and in the Dead Sea, where it was gathered and used in India as a textile mordant and in Egypt as a flux ingredient to make frit, an isolated copper pigment in glass. It was also used to make a water varnish from stick-lac, the alcohol based tree sap pigments could also be made water soluble in a borax solution. There is more data in, LAKE-MINERALS


Limestone is a sedimentary mineral cemented by calcium carbonate and is made of once living organisms, the dissolved mineral is calcite.
Lime mortar will exude a carbonate glass-like crust over time, cement will not.
In this same category of sedimented rock is salt and gypsum. Powered and heated or "calcined" limestone calcium and/or gypsum make plaster of Paris.
Mural mortar historically should be all calcium, as it contains no sulfur as gypsum does. Gypsum is stronger, add it and lime together to make a slower setting mortar for brick laying.

Today, 6-28-6, we have pigments that are lime and sulfur resistant. Sinopia sells them. This is leaning me towards an intonaco coat made of commercial white cement and small white sand or small crushed raw limestone sold as crushed marble meal and dust.

Gypsum's are crystals of hydrous calcium sulfate, crystal deposits formed as precipitates from sea water.
Gypsum crystals are called selenite when there clear and alabaster when they are translucent and fibrous. Satin-spar is opaque and bendable gypsum,
Gypsum heated forms sulfur dioxide gas and sulfuric acid. Gypsum heated in the presence of lead, either with fumes or in a natural combinations, it will form basic lead carbonate, called lead white. Lead white will turn brown in lime and turns these colors [metals] black; tins, coppers and cadmiums [they are sulfur colors], ocher's and earth's if poorly washed will also contain iron sulfates and darken. Nickel yellow and nickel Naples yellow are also effected. They don't seem to make much antimony Naples yellow any more but it is lime safe. Arsenic will also turn black.

Gypsum, after being heated loses most of its sulfur and becomes plaster of Paris.

CEMENT, like in Portland Cement, is made from heated gypsum, sand and alumina, the oxide of aluminum present in clay. That makes cement hydraulic, it absorbs water and the gypsum cement sets quickly, even under water. The addition of Alumina, present in clay, is the reason cement dries underwater. Both white and gray cement harden under water by this chemical reaction. The white cement I tested took two days to harden under water.
I tested white cement I got from a pool supplier with lime and sulfur safe colors from Sinopia and other suppliers and had as much open painting time as I have had with lime mortar.
It is just as easy to use dry pigments and a liquid acrylic polymer as the medium on a dry white cement support. (Secco) Use water based cera colla wax for the gloss finish or both the painting medium and finish.

Heated gypsum burns off sulfur as it becomes cement, any traces left behind would be bad for some mural pigments. So don't use gypsum plaster of Paris for murals, use limestone lime.
Plaster of Paris can be painted on after it dries as a secco fresco. Soak, or slake the lime from three months to twenty years, the longer the better. Start slaking with a very loose mixture fresh or 'powered once', slaked once, dry caustic lime or hydrated dry lime and water. Only the first and second drying of limestone lime will hold together strong enough for mural work. The lime you buy and use should be 94% calcium hydroxide. 92% lime is weaker and should be used in thinner layers. By the fifth drying out period the lime will have no holding power. It will be used as a white pigment when glue is added.
Cement does not get a hard calcium carbonate crust like lime does.

The first Scratch Coat or Rough Coat is 2-3 rough sand to 1 lime mortar.
The second Brown Coat uses medium sand at 2:1 lime mortar. These first two coats need to be floated rough with a wooden trowel or today's new float trowles, metal will not do.
The third coat is the top coat or Intonaco Coat. Use 1:1 lime mortar and a fine white sand, a crushed limestone or 'lime marble meal' which is larger than 'lime powder' for the last 'intonaco' coat. Three coats are better than one coat and six coats are better than three, for containing water. 1/8 inch or less 1:1 intonaco coat will stay wet longer, and exude more calcium carbonate. I use only one 1/8 inch intonaco coat.
All the lime dry coats must be cleaned of their top calcium carbonate, this is clear shiny crust that forms as the lime is drying now and for a long time afterwards. This dry crust will stop all rising calcium between layers. It must be allowed to pass right up to the top where it will add to the intonaco's calcium carbonate crust. That becomes the lime murals shining jewel, a hard finish to follow. Gypsum doesn't do that, it remains matt, is harder, and will absorb moisture.
This makes me think Michaelangleo used some gypsum in his lime because the ceiling is not shiny.

CEMENT FONDU is a cement with a high aluminum content,

KEENE CEMENT has alum salts added and makes a very hard mass.

CASEIN CEMENT, casein added to cement makes it harder and set faster. Not good for fresco, paint chips off.

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