picassoprints

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 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 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 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.

Glazing can be either glass or acrylic. Only glass should be used with any friable media such as unfixed pastels, charcoals, or graphite, never acrylic as it can damage the work by attracting these materials. There are many brands of acrylic glazing to choose from; one with an ultraviolet filter is recommended. The frame and the mat should be deep enough to prevent the artwork from touching the glazing. A stiff backboard behind the mat protects and supports the matted artwork. It is best to use non-acidic boards. A dust seal with paper or tape is also recommended. What damage results from using poor quality mat board? Avoid mat boards containing wood pulp which causes "matburn"--a darkening of the paper under the mat or at the bevel cut of the window mat. This type of stain permanently weakens the paper fibers and is not easily removed or lightened in conservation treatment.

Once a wooden sculpture has been dehydrated cracks will appear, where even exposure to high relative humidity will not make the cracks close up entirely. However, conservators can fill the cracks with a variety of materials to create a unified visual impression. What should I ask for when matting and framing works of art on paper? Mat board should be made from 100% rag or lignin-free cellulose. Sometimes those labelled as "museum board" or "conservation board" are not of the highest quality. Alkaline buffered boards are not sufficient if the board contains wood pulp. Photographs should not be matted with alkaline buffered boards as some prints are adversely effected by alkalinity. Hinges are used to attach the work of art to the backboard of the mat. They should be made of Japanese paper, and should be adhered with wheat starch paste. Pressure sensitive adhesive tapes and pre-gummed tapes should not be used. Photographs are often attached to the mat with photo corners.