Types of Reactions in Art and Artists’ Materials

Fall 2014

Double Replacement

Producing Acid-Free PaperWood pulp has natural acids; during production, acid-free paper may be treated with a mild base -usually calcium or magnesium carbonate -which neutralizes the acids and prevents the formation of additional acids.

H2SO3 + CaCO3 CaSO3 + H2O + CO2

http://www.catalogs.com/info/technology/what-is-acid-free-paper.html

Paper Making Continued

Much of the commercially produced paper today is acid-free. This is not due to the neutralizers added, but is largely the result of a shift from china clay to chalk as the main filler material in the pulp. Chalk is cheaper. It also reacts with acids and requires the pulp to be chemically neutral or alkaline.

china clay

http://www.catalogs.com/info/technology/what-is-acid-free-paper.html

Paper Manufacturing Process:

Paper Making ContinuedAnother feature is sizing. Paper can absorb ink. Sizing is used on fibers in order to reduce their tendency to absorb liquids; so ink stays on the surface of the paper, instead of being absorbed. The sizing additives mixed with the pulp must also be acid-free. Until 1980 mainly a rosin in combination with alum was used. When the paper industry started using chalk instead of china clay as filler, the paper chemistry had to switch to a neutral process. Today mainly AKD (alkyl ketene dimer) and ASA (alkenyl succinic anhydride) are used.

More Double ReplacementWhen acids in acid rain react with the stone/rock in statues, salt, water, and carbon dioxide are formed:

H2SO4 + CaCO3 CaSO4 + H2CO3 then

H2CO3 H2O + CO2 Marble statues are made of calcium carbonate.• When carbon dioxide and sulfur dioxide are in the air as pollutants, paintings can be damaged.• Some solid precipitates from double replacement reactions are used as pigments.

Single Replacement

• Rust gets its brick-red color from iron (III) oxide, Fe2O3:

• Fe + H2O Fe2O3 + H2

Synthesis

• Using acids to help egg dye adhere to eggs

Synthesis continued

• Copper patina: 2Cu + O2 Cu2O then 2CuO + CO2 + H2O Cu2CO3(OH)2 (green↓)

• Plating metals on jewelry

Copper Patina (Why it turns green!)

Patina on statues (most notably the Statueof Liberty [1]) is made of copper sheet: "The formation of patina varies with atmospheric conditions and may not even form in exceedingly dry conditions. Typically however, the “Statue of Liberty" tint does not make its entrance until around the 15th year or later. [2]”

Sources:[1] http://www.unc.edu/~jnrandal/sol.pdf[2] http://www.copperliquidpaint.com/Copper

Copper Patina Continued

“The composition of patina varies dramatically with location and may contain significant amounts of copper sulfate (CuSO4). One investigation (1932 [3]) of a 13 year old marine specimen found a composition of the patina to be (CuSO4) 2.5%, copper carbonate (CuCO3) 12.8% and copper hydroxide (Cu(OH)2) 52.5%.“

Source:[3] Handbook of Copper Compounds and Applications, H. W. Richardson, ed., CRC Press, Boca Raton, FL 1997, p 156.

Synthesis

• Para red dye is used in the making of American flags.• The final step of the reaction involves a “coupling” reaction with either

an amino containing aromatic ring or an alcohol-containing aromatic ring (phenol – aromatic ring with a hydroxyl group). For example, we can take the diazonium salt from p-nitroaniline and base-treated 2-naphthol and form para red.

• Figure 7: Synthesis of para red from p-nitroaniline and 2-naphthol.

Combustion

• Using a torch in welding• Using an oven in glass blowing• Wood burning

Decomposition• Sunlight breaks bonds in color molecules, causing them to

fade.• Concrete is a durable building material for sidewalks,

paths and driveways. The pitted surface of concrete can collect debris such as those from fallen leaves. As the leaves decompose, they may leach plant dyes and stain the concrete's surface. Carbohydrates in the leaves break down, aiding in the carbon cycle.

C6H12O6 CO2 + dyehttp://www.fs.fed.us/wildflowers/ethnobotany/dyes.shtml

• Several dyes are obtained naturally from plants decomposing:

.)

Dye Color Plant Common Name (Additional Colors)Yellow Dyes Yarrow (green, black)

Honey LocustGolden wild-indigo (green)Tall cinquefoil (black, green, orange, red)Pecan (brown)Indiangrass (brown, green)

Orange Dyes Western comandra (brown, yellow)Prairie Bluets (brown, yellow)Bloodroot (brown, yellow)Sassafras (black, green, purple, yellow)Eastern Cottonwood (black, brown, yellow)Plains Coreopsis (black, green, yellow, brown)

Red Dyes Ozark chinkapin (black, yellow, brown)Sumac (yellow, green, brown, black)ChokecherryPrairie Parsley (yellow, brown)Slippery Elm (brown, green, yellow)Black Willow (black, green, orange, yellow)

Purple / Blue Dyes Indian blanket (black, green, yellow)Hairy coneflower (brown, green, yellow, black) Red Mulberry (brown, yellow, green)Mountain alder (brown, red, orange)Summer Grape (orange, yellow, black)Black Locust (black, green, yellow, brown)

Green Dyes Butterfly milkweed (yellow)Texas Paintbrush (green, red, yellow)Basket flower (yellow)Sagebrush (yellow, gray)Stinging nettle Goldenrod (yellow, brown)

Gray Dyes Iris (black)Butternut (brown)Canaigre Dock (yellow, green, brown)

Brown Dyes Prickly poppy (green, orange, yellow)Texas Paintbrush (green, red, yellow)Elderberry (yellow)Downy Phlox (brown, green, yellow)

Black Dyes Northern Catalpa (brown, yellow)Sumac (yellow, red, green, brown)May-apple (brown, yellow)Sand Evening Primrose (green, orange, red, yellow)