If you can do just one thing to protect your collections you would be wise to choose controlling the environment. What does that mean exactly? In Preservation terms, it means 60-70 degrees Farenheit and 40-50% relative humidity with minimum fluctuations in either. It also means keeping light and pollutants out of collection areas as much as possible. Providing this environment reduces the rate of organic deterioration, keeps bugs and mold at bay, and limits exposure to potentially harmful light and dust.
We live in the real world and understand that not many people (let alone institutions) can maintain such strict conditions. So what can we do at home?
Keep your materials in a stable environment.
Large fluctuations in temperature and humidity (more than 5 degrees or 5% rH) are worse than being in a slightly warmer or wetter environment that is stable.
Store your materials where you live.
Do not store important items in the attic or basement, and definitely not out in the shed or garage unless these environments are controlled.
Keep materials off of the floor.
Store items at least six inches off of the floor to avoid water damage from water and insects.
Monitor for environmental damage.
Watch for fading and warping, or evidence of pests and mold.You can purchase inexpensive monitors at your local electronics store that tell you the temperature and relative humidity. If you discover a problem, contact a professional conservator for advice immediately.
Tip 2: Provide Proper Enclosures
Enclosures provide protection from light, dust and handling. We think they may provide a microclimate that can may mitigate small fluctuations in temperature and relative humidity. We have also seen boxes that have gotten wet wherein the contents have been dry, the box having soaked up the moisture before getting to the contents (do not count on this as your disaster plan, however).
An enclosure can be a box, envelope, folder or picture frame, anything that provides protection from the elements. What makes a "proper" enclosure?
Fit is important.
An enclosure should be just slightly larger than the contents. If it is too small, it may cause damage (think of shoes that are one size too small, ouch). If the enclosure is too large, the contents can move around and bash into the sides. This is particularly bad for brittle and fragile items.
What the enclosure is made of matters, too.
Enclosures are usually made of paper or plastic, choose based on whether you need rigidity and light protection (paper) or need to see through the enclosure to reduce handling (plastic).
Enclosures made of paper such as folders and boxes should have a pH between 7.0 and 8.5 and be lignin free.* Acidic and lignin-containing enclosures can cause paper to become brittle and discolored.
Plastic enclosures such as slide or page protectors should be made of stable, preservation-quality plastics. These are polyester (trade names Mylar and Melinex), polypropylene and polyethylene. If you can't determine what type of plastic it is, don't buy it. Avoid vinyl because it offgases and causes discoloration and brittleness.
*Warning: When choosing enclosures from vendors you must be an informed consumer. The term "Acid Free" is a marketing ploy and does not tell you if the chemistry of the materials will harm or protect your artifacts. Think about it...would you put your priceless artifacts into a bath of drain cleaner? After all, most drain cleaners are "acid free" because they are very strong bases. So strong they can dissolve whatever they come in contact with. If you are unsure of the actual pH, ask the manufacturer or choose something you know is safe. When in doubt, choose a pH neutral (pH of 7.0) container.
Resources
NEDCC "Storage Enclosures for books and Artifacts on Paper"
NEDCC "Temperature, Relative Humidity, Light and Air Quality"
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