Drying out/dehydrating silica gel bags

[mental4astro]

Hi all,

I've got a few bags of this silica gel stuff in with my scopes. Some of which is a few years old. I've heard about 'recharging' them by heating, but I'm just not sure how or where to do this. Out in the sun, or a warm oven (<70*), and for how long to dry them out for.

Any one have more of an idea?

Cheers,

Mental.

[GeoffW1]

Hi Alex,

I recall looking this up on a gel manufacturer's website, and the result was to place them in the oven at 120 deg C for 3 hrs. Much above that apparently, some types of gel can be made ineffective.

Cheers

[mental4astro]

Ta, Geoff.

[multiweb]

I just microwave them for 10-15s. Gets all the water out real quick.

[coldlegs]

This article might help reveal some tricks used.
http://www.agmcontainer.com/desiccant_reactivator_unit/PDFs/reactivatorUnit.pdf

cheers
Stephen

[Barrykgerdes]

When I used to work at the DRC we had silica gel packets in lots of equipment being maintained like portable radio packs and submarine bouys . If I remember rightly we had a smallbox with a 60 watt lamp globe in it. All the silica gel satchels and plugs got thrown in it to be dried out.

Barry

[allan gould]

We used silica gel all the time in the lab and used a vacuum oven at 140 C for several hours or 30 sec bursts in a microwave and rest for 30 secs in between until turns blue, about 5 bursts ( had a colour indicator in it).

[AstralTraveller]

The blue silica gel is now out of date because it is considered unsafe. The indicator was CoCl2. The cobalt is toxic and the stuff did tend to power up. Newer silica is orange when dry and clear(ish) when wet and the beads don't tend to turn to powder.

[George Ionas]

In the lab we heat the silica gel in a laboratory oven to 180 degrees C for 3 hours. DO NOT do this in the home oven or microwave as CoCl2 (the blue dye) is a carcinogen.

George

[GrahamL]

We used to dry them out in the pie warmer in the lunch room
not a good idea eh ?:confused2:

[mental4astro]

Sounds like its a job for a solar heater: a black recycling box with an old glass window covering it, and chuck the silica gel bags into the box. These solar heaters get real hot in the sun. Left out in the sun over a day or two should do the job then. I won't be licking the inside of the recycling box any time soon either, :P.

[ZeroID]

Now THATS a good idea !!
Might need some small vents in the box to let the moisture out. Other wise you might have to chuck in some Silca Gel to dry it out after ... :question:

(I get quite a few of these wee packs. Might build one to see how it works. Use them with the camera gear mainly.)

[multiweb]

I use the dessicant strips which don't hold the blue/pink die. Is it still safe to microwave them?

[George Ionas]

The carcinogen is the indicator dye Cobalt chloride.

George