Types of Reactions in Art and Artists’ Materials

Lajeunesse, Spring, 2012

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Synthesis• Using acids to help egg dye adhere to eggs

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Double Replacement

Producing Acid-Free Paper

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

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

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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.

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

Sizing

• Another 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.

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

More Double Replacement

• When acids in acid rain react with the stone/rock in statues, salt, water, and carbon dioxide.

• 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

• Copper patina • Plating metals on jewelry

•

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Copper Patina (it turns green!)• Patina on statues (most notably the Statue of

Liberty [1] that 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_…

http://www.destination360.com/north-america/us/new-york/nyc/statue-liberty

Copper Patina Continued• The composition of patina varies dramatically with

location and may contain significant amounts of copper sulphate (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.

Combustion

• Using torch in welding• Using oven in glass blowing• Wood burning ehow.com

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Synthesis• One dye forming reaction involves a “coupling” reaction with either an

aminocontaining 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, the dye used in making American flags.(Figure 7)

• Figure 7

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Decomposition

• I didn’t find a good chemical reaction, but…

• Chinese artists decompose their art into brush strokes

• Some artists specialize in artwork featuring decomposition and decay.

• Sunlight breaks bonds in color molecules, causing them to fade.