A Beginners Guide to Desiccants

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Packets of SeedsThe concept of using desiccants has always been a bit confusing to me.  Conceptually, I knew what they were, namely little packets of gel  that are packaged with electronic gizmos, new shoes, pill bottles and even clothing purchased over the internet.  I also knew that  many articles, books and websites with information about long term food storage also talked about desiccants.

But what are they?  How are they used?  And are they really necessary?  It seems that depending upon who you consult, they are absolutely 100% necessary or a waste of time and money.  Talk about being confused.  Still, about three months ago I started saving all of those little packets thinking that at some point, I would try to figure out what to do with them and why.

What is a Desiccant?

Starting with its most basic definition, a desiccant is is a substance that absorbs water. It is most commonly used to remove humidity that would normally degrade or even destroy products sensitive to moisture.

Okay. Now I get it.  As an oxygen absorber is to air, a desiccant is to moisture. That means, if I understand correctly, items that may be subject to mold and mildew if left unprotected in a damp area will be safe from those nasties if stored with a little desiccant packet on board.

There are many types of desiccants.  Wikipedia has a fairly lengthy list of desiccants but instead of burdening myself with figuring them out on my own, I asked my friend Ron Brown to share his knowledge of desiccants as well as the results of his experiments using various types of this magical stuff.

silicagel 2

Here is some of what he shared with me.

Some Common and Not So Common Desiccants

silicagel 1Silica Gel:  Silica gel is one of the more common desiccants.  Crafty types use it to dry flowers and in other projects.  As with other desiccants, as water evaporates from the flowers, it’s soaked up by the gel, thus drying them out for posterity.  Packets of silica gel are also found packaged with pills, over the counter remedies and vitamins.  What many people do not know is that these can be reused if you dry them out using low heat in the oven.

Salt:  Salt is a desiccant. If it cakes in the shaker and won’t come out, that means it’s soaked up moisture from the air and the little grains of salt have glued themselves together. To prevent caking, calcium silicate is added to table salt.

Rice:  Rice is added to salt shakers to keep the salt flowing freely. So if salt is a desiccant, maybe rice is an even stronger desiccant.

Calcium Chloride:  Ron indicates that he totally ruined a pair of leather shoes once, spreading calcium chloride with a shovel off the back of a flat-bed truck (to minimize the blowing dust) back in his college-student, summer-job, road-construction days.

Cement and plaster of Paris:  Both cement and plaster of Paris are “calcined” at high temperature and will gradually harden if left setting around the in the garage. They absorb moisture from the air. They are desiccants.

Powdered Non-Dairy Creamer:  A bowl of powdered non-dairy creamer will gradually harden if left on the table unused.  Yes, scary as this sounds, non-dairy creamer is a desiccant.

Plasterboard or Wallboard:  Ever heard of a Kearney fallout meter?  When building a Kearny fallout meter to detect radiation – a topic for another day – you must have a desiccant in the cell to keep the atmosphere as dry as possible. Kearny himself recommended a piece of wallboard or plasterboard that has been broken into half-inch cubes and dried in the oven.

So Which Desiccant is Right For You?

Now here is where things get interesting. Ron ran some experiments testing various types of desiccants and was kind enough to share the results and a tip for making your own desiccant packets below – in his words.

So which desiccant is best?

To answer that question, I took one cup each of silica gel, salt, rice, calcium chloride, plaster of Paris, and non-dairy creamer, poured them in separate bowls, then lined the bowls up on a table in the cellar. Relative humidity was in the 65-75% range. I weighed them in the beginning, gross and tare, and at the end of 40 days.


And the winner is . . .  Calcium chloride!

The net start weight of the calcium chloride – CaCl2 – was 224 grams. The net finished weight was 349 grams. So one cup of calcium chloride picked up 125 grams of water in 40 days, a gain of 56%. (It also doubled in volume.)

CaCl2 - after

The non-dairy creamer was first runner-up. One cup of non-dairy creamer picked up 20 grams of water, an increase of 16%.

None of the others (including the store-bought silica gel) picked up enough moisture in 40 days to measure. The silica gel had a net start weight of 225 grams and an end weight of 225 grams. That’s for 40 days. No doubt a year would tell a different story.

Even so, calcium chloride was the clear winner. Please note that a hard, half-inch thick crust had formed over the surface of the calcium chloride. The crust was almost like concrete, really quite difficult to chip away without breaking the dish.

So where can you buy calcium chloride? One place is in with the canning supplies, sold by Ball as “Pickle Crisp Granules” (5.5 oz. for $6). It makes the pickles crunchy and is used in commercial dills (Claussen, for example).

CaCl2 1

It’s cheaper to buy Morton Safe-T-Power ice melter in plastic cans, 9 lbs. for $5. People use it on their outside steps and sidewalks in winter to melt ice. If you buy pallets of calcium chloride in 50-lb. bags, you can get it for $12 a bag. Tractor-trailer loads are even less.

I put “packets” of desiccant in with my vegetable seeds.

packet type 1

I make the packets from coffee filters (Mr. Coffee-type), cutting, folding, and stapling as necessary. Don’t forget that calcium chloride can potentially double in volume from its original (dry) size. So don’t stuff the packets. More is not better.

Were I to use larger containers – 5-gallon buckets, say, or 30-gallon trash cans – for storing grains, flour, and the like, then I would not use fragile coffee-filter packets. I would use old vitamin bottles or mayonnaise jars (of whatever size seemed appropriate for the task at hand) with many small holes punched in the lid. Jars LABELED with what’s inside, thank you!

packet type 2

But whatever desiccant you choose and however you use it, it is crucial to the success of your storage program. Crucial, critical, important, essential, indispensable, all that stuff.

The Final Word

Clearly, we need a desiccant to put in with the vegetable seeds we’re storing for next year.  It also seems to me that it might not be a bad idea to include a desiccant in with the grain we hope to store for decades.  After all, who wants to go through the time and expense of storing grains for the long term only to have it get smelly, damp and moldy and further, making you sick when you eat it.

I would like to thank Ron for his help in educating me and also for generously sharing his experiment and as well as his method for creating DIY desiccant packets using coffee filters and a bit Calcium chloride or non-dairy coffee creamer.  Seems to me that the next task at hand is to ask him to show us how – in pictures – to build a Kearny fallout meter.

I would also like to put in a plug for Ron, who is the author of  Lanterns, Lamps & Candles.  This e-book on CD is a comprehensive handbook of non-electric lighting.  I have no financial interest in the product (no commissions or anything), just a huge fan of both the CD and Ron!

Enjoy your next adventure through common sense and thoughtful preparation!


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Bargain Bin: Thinking of making up your own packets of desiccants?  Here are some of the product that will get you started.

Ball Pickle Crisp 5.5 oz. Jar: You can make up a large batch of desiccant packets with this tub of “pickle crisp” and some coffee filters such as the Brew Rite #4 Cone Coffee Filters.

DampRid Hi-Capacity Moisture Absorber, 4-Pound TubThis is Calcium Chloride. This stuff has been used by boaters for years and is a popular item.  Seems to me that a 4 pound tube, used to make desiccant packets, would like forever.

Dry-Packs 3gm Cotton Silica Gel Packet, Pack of 20:  These premade packets of silica gel can absorb 40-percent of its weight in water vapor.   There are also these larger packets Dry-Packs 1-Ounce Moisture Absorbing Silica Gel.

20 – 300cc Oxygen Absorbers for Dried Dehydrated Food and Emergency Long Term Food StorageEven if you choose to take a pass on desiccants, oxygen absorbers are a must for preserving bulk foods and grains for ling term storage.

Zwipes Microfiber Cleaning Cloths, 36-Pack:  Thought I might remind you that microfiber cleaning cloths aka magic rags are my absolute favorite for cleaning. Although machine washable and dryable, sometimes I simply hand wash the cloth I am currently using and let it hang to dry.  I use the an napkins when eating and as a bib when I want to protect my clothes from messy spills.  I love these things – I just wish they would wear out so I could get some new ones in different colors.

Soft White WheatShop the Emergency Essentials Monthly Specials: The monthly specials at Emergency Essentials feature discounts of up to 35% off sometimes a bit more. Even if you are not ready to buy, take a look at their robust list of Food Storage Recipes – yours for the taking.

Specials that I like this month are their SUPERPAIL of Soft White Wheat, a Deluxe Grain Mill and Motor and the Provident Pantry Freeze Dried Meat Essentials Combo. The grain mill is on sale for $123.98 (normally $189.99).

Want to try something different?  How about some Freeze Dried Banana Dices?

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A Beginners Guide to Desiccants — 7 Comments

  1. Thanks to Gaye & Ron for such a great article! I knew basically what desiccants were and what they were used for, but had never gone the extra step to what I needed to do with them.

  2. Great simple explanation of desiccants. Proper protection from moisture is important. To that end, combining our moisture barrier bags with a desiccant is one of the most efficient ways to protect your goods. No matter how effective a moisture barrier bag may be, there is always a possibility that a minute amount of moisture may seep in. The use of desiccants is a smart preventive measure for added protection.

  3. Gaye,
    Wow the timing for this article is awesome. We were just discussing this the other day, Thanks again for all you do, and thanks for info on this subject as well.

    • @Billy – I do not have personal experience with kitty litter but I did find this on Wikipedia:

      “Silica gel is also used as cat litter by itself or in combination with more traditional materials, such as clays including bentonite. It is trackless and virtually odorless. Purchasing silica in the form of cat litter can be an easy and cost effective way for retail consumers to purchase silica gel for use in other applications, such as maintaining the desired relative humidity in humidors, keeping tools or other materials rust-free in damp environments or long-term storage, and preserving dried food.”

      So I would say yes.

      — Gaye

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