In general, works of art and antiques require some special attention, preventive conservation measures, to guarantee their preservation and prevent any loss of value. Artworks and antiques are usually a combination of different materials joined together. Precisely this characteristic is what makes them fragile and susceptible to damage. Pigments, binders, varnishes and a main support –fabric or wood panel- are main components in paintings; paper and different types of inks are elements in documents, prints, watercolors, etc.; alloys of diverse metals are present in metal sculptures; ramie, feathers, threads, beads, etc., can be found in ethnographic materials, and so on. It is the presence of all these different materials, with the diverse responses to environmental factors as humidity, light and air pollution what gives them its idiosyncratic fragility.
- Effects of high relative humidity on paper. The proper preventive conservation measures would have prevent the damage.
Relative humidity (RH) is a decisive factor in the preventive conservation field. High RH causes the development of mold and fungi as well as the corrosion of metals. Low RH causes the embrittlement and breakage of moisture containing materials such as wood, bone, basketry or leather. With these considerations in mind, the choice for the relative humidity level would depend on your collection and factors that go with it but, as a general rule, it should be as close to 50 or 55% RH as possible, and what is more important, it should be maintained as leveled and uniform as possible. Continuous ups and downs of the RH will cause a repetitive expansion and contraction of the materials and consequently will contribute to the development of cracks and fissures, not noticeable at the beginning but that will aggravate with the passage of time. Usually RH is well controlled by air conditioning and no sudden changes should be expected unless the system is malfunctioning, but remember: Do not switch off the air conditioning because you are out of town, even if it is for a few days. The rise of the HR while you are out and the dropdown when you come back can cause struggles to your collection.
To be continued…
