What is the cause of dark spots that sometimes appear on the paper of drawings and paintings? Reddish-brown spots are known as "foxing", caused by mold or the deterioration of the metallic impurities left in the paper from the manufacturing process. Other colors of spots may be one of many types of mold damage. Mold spores are everywhere in the environment, and mold thrives on cellulosic materials, especially in conditions of high humidity (above 65% of relative humidity). Keeping artworks out of high humidity areas like bathrooms artwork by famous artists and artists or exterior walls, can help reduce the development of such stains. if i have a work of art on paper that appears to not be flat, should i be concerned? paper is hygroscopic, reacting to changes famous in climate by expanding when it is humid and contracting when it is dry. a gentle undulation in the paper called "cockling" occurs under these conditions, especially with larger works. this may impair the work artists aesthetically as well as cause mediums such as gouache to crack or flake as it is unable to expand and contract as the paper itself does.

bronze is an alloy of copper with other metals that modify its hardness, color, and ability to be cast into a detailed mold. when bronze is cast it is usually a gold color. after the casting and finishing is completed, the surface is often treated with chemicals and heat which patinates the metal, coloring it green, brown, black, or a combination of the colors. foundries usually apply waxes or other coatings to the surface of a patinated outdoor bronze to protect it from pollutants. this wax may wear off in time. we recommend annual maintenance by a professional conservator. the surface of the sculpture may be washed to remove pollutants and dirt, and waxed. if done annually, the rate of corrosion will be retarded (though not totally eliminated), and disfiguring rain streaks will be minimized. famous and artists i collect twentieth-century furniture. how can i best preserve it? some twentieth-century furniture famous was created from non-traditional materials, such as foam, plastic, artists and cardboard.