dehumidifying

[Allan Fyfe]

I have a shed which I store tools in - winter is coming and to save removing the tool chests and taking them in to the "heated" workshop ( some bits are none too warm!) I am going to put a container of dehumidifying crystals in each one and see how that works. I have used these before and been impressed by the amount of water that these crystals attracted.
I found this on the internet and thought it was quite helpful;

Chemicals that absorb moisture — silica gel, activated alumina, anhydrous calcium sulfate and molecular sieves may be used to absorb moisture from the air. These chemicals are not likely to be found in department stores, drug stores or hardware stores. In metropolitan areas, look in the yellow pages of the telephone book for scientific supply houses and suppliers of industrial chemicals. In rural areas or small towns, contact your local University Extension center, high school chemistry teacher or the chemistry department of a college or university. Some of these chemicals are sold under various trade names by several companies, and others are produced by only one company.

These chemicals are not harmful to fabrics and feel dry even when they saturate the cloth. Hang cloth bags of the chemical in clothing closets. Or place an open container of it in the closet — on a shelf, preferably, or on the floor. See that the door is well-sealed and kept closed so that moisture from outside air will not get in. You may scatter the dry granules through layers of clothing and other articles that are to be stored in tightly closed chests or trunks.

All of these chemicals can be used over and over if you dry them between uses. Simply place the granules in a vented oven at 300 to 350 degrees F (149 to 177 degrees C) for several hours. Then put the hot granules in an airtight container to cool. Silica gel and anhydrous calcium sulfate (specially treated with a color indicator) are pink when full of moisture, blue when dry.

Another chemical that absorbs moisture from the air is anhydrous calcium chloride. Calcium chloride is used in some states for melting snow on the highways, so your local road department may be able to furnish names of suppliers. The chemical is available in small, white granules that hold twice their weight of water. But it liquefies as it absorbs moisture. So do not let this chemical touch clothing or household textiles; it can make holes in them.

To use anhydrous calcium chloride, place the granules in a simple, cup-shaped container made from nonrusting screen or waxed cardboard (milk carton) perforated with small holes. Support the container in an enameled pot so the liquid can drip away from the container, leaving the calcium chloride to take up more moisture. Then place the pot in the closet, preferably on the shelf, and keep the door shut and sealed. One pound (454 grams) of calcium chloride will last from 2 weeks to 2 months, depending on the humidity. When only liquid is left, discard the liquid and start over.

Caution: Add water to the liquid before disposing of it.


I looked for a branded container and supplier of the crystals on the Internet and quickly gave up - they all wanted to sell me machines ! but, as I said earlier,I have bought one of these before. I'll make something up