Re: OT- Silica Gel

[David Mann]

On Jan 19, 2010, at 4:35 PM, Subash wrote:

> This has to be done because once
> the gel absorbs the moisture in the box, it doesn't work anymore.

Not long after I started an internal tech-support job at an electronics 
manufacturer we had to deal with an issue where the units we shipped would sit 
around in their boxes for a few months waiting for installation.  They would 
often be left sitting in some pretty humid environments as we exported 
worldwide.

The unit would be wrapped in a plastic bag within the box, with a bag of silica 
gel thrown in.  It turned out that the plastic would slowly leach moisture.  
Given enough time it'd saturate the silica gel to the point where it'd cause 
rusting where its bag contacted the metalwork.

I'm not sure how that particular one was solved as someone else dealt with it.  
I think the solution was to find a different type of plastic.

Dave
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Re: OT- Silica Gel

[John Sessoms]

From: Bong Manayon

On Tue, Jan 19, 2010 at 1:23 AM, John Sessoms  wrote:

> From: Bong Manayon

>>
>> Anyone know anything about recharging silica gels/desiccants?

>
> Put 'em on a cookie sheet in the oven at low heat for a couple of hours;
> about 95 deg C or 200 deg F seems to work.
>

You've done this?  I suppose you take them out of their bags?


Been a lot of years, but I have done it.

Used to have a bunch of reusable ones, and that's what the directions 
said to do with 'em; stick 'em in the oven at low heat for a couple hours.


Turned pink when they absorbed moisture, and turned blue again when they 
were dried out. Instructions didn't say to take it out of the bag, so I 
didn't.


With low heat, it shouldn't be a problem.

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Re: OT- Silica Gel

[Bong Manayon]

On Tue, Jan 19, 2010 at 11:35 AM, Subash  wrote:
>
> Bong, actually i happened to ask the guy a while back how he went
> about it and i still have his reply. quoting verbatim (and i have never
> done this myself):
>
> 
> from a chemist I bought half a kilo of silica gel. I keep the silica
> gel wrapped up in a handkerchief in the airtight box along with my
> equipment and secure the lid. This is very very effective. About once a
> week (when I'm not using the equipment, i.e, when I'm not opening the
> box too often) I remove the silica gel and put it in an oven, set to 50
> degree celsius for about half an hour. This has to be done because once
> the gel absorbs the moisture in the box, it doesn't work anymore. When
> the gel is dry, it is a beautiful, deep blue in colour. Once it has
> absorbed moisture beyond its capacity, it turns pink. If you heat it at
> a low 50-60 C in an oven or microwave, it'll turn blue again.
> 
>
Thanks!  This is very useful!

Cheers!

Bong
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Re: OT- Silica Gel

[Subash]

On Tue, 19 Jan 2010 10:38:32 +0800
Bong Manayon  wrote:

> On Mon, Jan 18, 2010 at 7:32 PM, Subash  wrote:
> > i have friends who periodically micro-wave it... :)

> Yeah, I do the sunshine thing too, but this is the first time I heard
> about microwaving them (I know about putting them into an oven).
> 
> You would not happen to know how they actually do it?  I.e., take them
> out of the bag?  How long...?

Bong, actually i happened to ask the guy a while back how he went
about it and i still have his reply. quoting verbatim (and i have never
done this myself):


from a chemist I bought half a kilo of silica gel. I keep the silica
gel wrapped up in a handkerchief in the airtight box along with my
equipment and secure the lid. This is very very effective. About once a
week (when I'm not using the equipment, i.e, when I'm not opening the
box too often) I remove the silica gel and put it in an oven, set to 50
degree celsius for about half an hour. This has to be done because once
the gel absorbs the moisture in the box, it doesn't work anymore. When
the gel is dry, it is a beautiful, deep blue in colour. Once it has
absorbed moisture beyond its capacity, it turns pink. If you heat it at
a low 50-60 C in an oven or microwave, it'll turn blue again. 


hth, subash


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Re: OT- Silica Gel

[Bong Manayon]

On Tue, Jan 19, 2010 at 1:23 AM, John Sessoms  wrote:
> From: Bong Manayon
>>
>> Anyone know anything about recharging silica gels/desiccants?
>
> Put 'em on a cookie sheet in the oven at low heat for a couple of hours;
> about 95 deg C or 200 deg F seems to work.
>
You've done this?  I suppose you take them out of their bags?

Bong
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Re: OT- Silica Gel

[Bong Manayon]

On Mon, Jan 18, 2010 at 7:32 PM, Subash  wrote:
> On Mon, Jan 18, 2010 at 4:06 PM, Bong Manayon  wrote:
>> Anyone know anything about recharging silica gels/desiccants?
>
> i have friends who periodically micro-wave it... :)
>
> i just keep them out in the sun all day once in a while. don't know
> whether that answers your question. :)
>
> regards, subash

Yeah, I do the sunshine thing too, but this is the first time I heard
about microwaving them (I know about putting them into an oven).

You would not happen to know how they actually do it?  I.e., take them
out of the bag?  How long...?

Bong
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RE: OT- Silica Gel

[Bob W]

> 
> Put 'em on a cookie sheet in the oven at low heat for a 
> couple of hours; about 95 deg C or 200 deg F seems to work.
> 

Has this leaked over from the squirrel thread?



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Re: OT- Silica Gel

[Cotty]

On 18/1/10, John Sessoms, discombobulated, unleashed:

>Put 'em on a cookie sheet in the oven at low heat for a couple of hours;
>about 95 deg C or 200 deg F seems to work.

heh heh heh



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Re: OT- Silica Gel

[John Sessoms]

From: Bong Manayon

Anyone know anything about recharging silica gels/desiccants?


Put 'em on a cookie sheet in the oven at low heat for a couple of hours; 
about 95 deg C or 200 deg F seems to work.


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Re: OT- Silica Gel

[P. J. Alling]

I've never done this, but I've been told that if you place them on a pan 
and heat them in an oven at no more than 200° F they will be as good as new.


On 1/18/2010 5:36 AM, Bong Manayon wrote:

Anyone know anything about recharging silica gels/desiccants?

Bong
   



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{\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{\f0\fnil\fcharset0 Courier 
New;}}
\viewkind4\uc1\pard\f0\fs20 I've just upgraded to Thunderbird 3.0 and the 
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Re: OT- Silica Gel

[eckinator]

Example of those who can't:
http://www.drierite.com/default.cfm?gclid=CPjWnMvrrZ8CFc0SzAod_juP0Q
Also: (Google is my friend)
http://www.ashirwadchemicals.net/faq-s.htm
Hence, it is actually 100-120°C for silica gels

Sounds like an insane waste of energy... nuking is probably the better
idea if you can control the temperature

The McGyers amongst us should look here =)
http://www.thaiscience.info/Article%20for%20ThaiScience/Article/3/Ts-3%20the%20regeneration%20of%20silica%20gel%20desiccant%20by%20air%20from%20a%20solar%20heater%20with%20a%20compound%20parabolic%20concentrator.pdf

Cheers
Ecke

2010/1/18 eckinator :
> 2010/1/18 Bong Manayon :
>> Anyone know anything about recharging silica gels/desiccants?
>>
> As far as I know the vast majority can just be put into the oven at
> 80°C, bake till dry
> Cheers
> Ecke
>

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Re: OT- Silica Gel

[eckinator]

2010/1/18 Bong Manayon :
> Anyone know anything about recharging silica gels/desiccants?
>
As far as I know the vast majority can just be put into the oven at
80°C, bake till dry
Cheers
Ecke

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Re: OT- Silica Gel

[Subash]

On Mon, Jan 18, 2010 at 4:06 PM, Bong Manayon  wrote:
> Anyone know anything about recharging silica gels/desiccants?

i have friends who periodically micro-wave it... :)

i just keep them out in the sun all day once in a while. don't know
whether that answers your question. :)

regards, subash

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