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Full Version: DampRid, Dri-Z-Air, etc Question
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When van people talk about insulation, they also seem to worry about moisture.

I was wondering about the use of silica gel granules.  You do have to dry them out again when they change color.  And then I remembered that I forgot to check my dollar store brand of DampRid.  I bought them during the summer.  Our W. WA rains have started, so I checked them in my leaky unused bedroom...  well, once I started to think about the silica gel...

The stuff I have is called Moisture Eliminator (from the Dollar Tree).  A couple of other brand names are DampRid and Dri-Z-Air.  All of these products contain Calcium Chloride, a salt (this is not table salt, which is Sodium Chloride).  My units are smallish (maybe 2 cups) plastic containers with a perforated rack about halfway up, with some calcium chloride granules sitting on the rack.  There is a fabric-like material sealed across the top of the container, covered by a seal of foil, and a pull-off plastic grid on the top.  When you want to put it in use, you pull off the black grid, peel off the foil, replace the grid, and set the unit where you think it would be useful.

After it's been sitting for a while (exposed to moisture), the granules clump together.  Then, as they absorb more moisture from the air, the excess moisture drains through the rack to the bottom of the container.  The instructions say that when the granules  have dissolved, to pull off the faric top and pour the liquid down the drain.  This stuff is corrosive to metal, so they warn to have the water running while you're doing this.  Then you discard the container and buy another one.

Okay, this is fine.  I might even put one in my van, when I get it.

[I'm leading up to a question...  Big Grin ]

It's been about five months since I opened the seal and put them in place.  Today, I took the cloth top off one of them, poured out the contents, rinsed it, noticed the knob on the rack and pulled up on it.  The rack lifted out quite easily.  But, below the rack, sitting on the bottom of the container was a solid crystal-like mass about 1/2" thick.  I turned the container upside down and whacked it on the bottom of the sink.  The clump fell out in three chunks.

It looks like salt.  It must be salt.  It must have absorbed moisture, liquified, dripped through the rack, and eventually (don't know the time frame) reformed into salt again -- the same stuff that made up the granules on top of the rack.

Just as a possible cash-saving experiment, I dumped all of the clumps out of the four containers after draining them of liquid, replaced the racks, and then put the broken pieces on top of the racks, and replaced the plastic grid and put them back in the leaky bedroom.

Here's the question:  as long as the salt granules are supposed  to clump together, and they've now been elevated above the bottom, and the container is reasonably dry, do you think this will work?  I've looked online, and no one refers to the lump on the bottom.  Do you think this will continue to work as a dehumidifier?

How long do you think it took for the salt to re-solidify in the liquid?

If all the above sounds reasonable, these things seem to be able to be recycled for the original purpose, rather than discarded.

Is my thinking reasonable, or am I missing something obvious?
Almost any suspended solid will eventually fall out of suspension and reform into a solid.

Try it is all I can say. What is there to lose?

If you are concerned about the moisture, put a new one in with the old recycled one and see what happens.

Djkeev: That's too obvious!
Can't say for sure the answer to your question, but if you're looking for this stuff on the cheap then you can save money buying it in bulk. Calcium chloride is sold both as ice melt and as a spread to keep dust down on dirt roads. It is available at any hardware store or agricultural supply in these forms. SuperMelt is one brand of calcium chloride ice melt.
TMG51 -- If it takes too much time to turn back into salt, that might be a cheap way to refill the containers!
also I would recrush the clumps. more surface area. a simple mortar and pestle will take care of that. highdesertranger
HDR: Actually, I thought of that, but they were wet, and the first thing the granules do when exposed to moisture is clump together. Also, the rack they sit on would let any fine stuff sift through. I'll try it in lumps first, and see how that goes. Then, I guess there might be more experiments on 'My List'. And it's getting longer by the day.....

Thanks for the suggestion, though!