Silica Gel Question

westclox · 13th April 2007

Hi,
For those really good in Chemistry, is silica gel a plastic? Cos I scared that if I heat too strongly it will melt and catch fire.

ipin · 13th April 2007

It's not a gel, but crystaline in structure. The Freezing/Melting Point of the kind of Silica Gel Desiccant Grade (Blue indicating grade) is 1710ºC!

I doubt most of us can have access to euqipment to heat stuff to this kind of temperatures!

I have heated them to 120ºC in an oven before and they've been regenerated for re-use.

Do take note : The Silica Gel Desiccant Grade contains Cobalt(II) Chloride as an indicator (Which is why the color changes from blue to pink whan saturated with H2O and a prolonged exposure to respirable crystalline quartz may cause delayed lung injury/fibrosis (silicosis). Cobalt compounds may cause cancer based upon animal studies.

PhotoTime · 13th April 2007

Originally Posted by ipin

It's not a gel, but crystaline in structure. The Freezing/Melting Point of the kind of Silica Gel Desiccant Grade (Blue indicating grade) is 1710ºC! I doubt most of us can have access to euqipment to heat stuff to this kind of temperatures! I have heated them to 120ºC in an oven before and they've been regenerated for re-use.

Do take note : The Silica Gel Desiccant Grade contains Cobalt(II) Chloride as an indicator (Which is why the color changes from blue to pink whan saturated with H2O and a prolonged exposure to respirable crystalline quartz may cause delayed lung injury/fibrosis (silicosis). Cobalt compounds may cause cancer based upon animal studies.

Wow! This is the first time I get the information on Silica Gel.

Do you mean that we will get intact with the Cobalt(II) Chloride even if we touch the Silica Gel? Is it safe to use microwave to reheat the Silica Gel to dry it?

skopio · 13th April 2007

no, don't reheat. its so cheap, just replace it.

ipin · 13th April 2007

Originally Posted by PhotoTime

Wow! This is the first time I get the information on Silica Gel.

Do you mean that we will get intact with the Cobalt(II) Chloride even if we touch the Silica Gel? Is it safe to use microwave to reheat the Silica Gel to dry it?

I wouldn't use the microwave as it is in an enclosed space. U'll come into contact with the fumes when you open it. Besides, u'll and your loved ones would be using the same microwave to heat up food. I rather not take the risk.

If you want to regenerate it, do so in a WELL ventilated area with a pan used solely for this purpose only. Try to minimise cross-contamination with your silica gel regeneration activities.

Yes, you'll come into contact with Cobalt(II) Chloride when you touch/handle it.

antitrust · 13th April 2007

I heat them up using an old, unused pan in a well-ventilated kitchen.

After a few cycles of heating it up and reusing it, the pink indicator might wear off and become a very faint pink or sometimes transparent. However, when you heat it up again, It will turn back to the dark blue colour as in the case of a dry silica jel bead.

13th April 2007	#1
westclox Member Join Date: Jan 2007 Posts: 475	Silica Gel Question Hi, For those really good in Chemistry, is silica gel a plastic? Cos I scared that if I heat too strongly it will melt and catch fire.

13th April 2007	#2
ipin Senior Member Join Date: Nov 2005 Posts: 5,449	Re: Silica Gel Question It's not a gel, but crystaline in structure. The Freezing/Melting Point of the kind of Silica Gel Desiccant Grade (Blue indicating grade) is 1710ºC! I doubt most of us can have access to euqipment to heat stuff to this kind of temperatures! I have heated them to 120ºC in an oven before and they've been regenerated for re-use. Do take note : The Silica Gel Desiccant Grade contains Cobalt(II) Chloride as an indicator (Which is why the color changes from blue to pink whan saturated with H2O and a prolonged exposure to respirable crystalline quartz may cause delayed lung injury/fibrosis (silicosis). Cobalt compounds may cause cancer based upon animal studies.

13th April 2007	#4
skopio Member Join Date: Nov 2006 Posts: 745	Re: Silica Gel Question no, don't reheat. its so cheap, just replace it.

13th April 2007	#6
antitrust Member Join Date: Sep 2004 Posts: 318	Re: Silica Gel Question I heat them up using an old, unused pan in a well-ventilated kitchen. After a few cycles of heating it up and reusing it, the pink indicator might wear off and become a very faint pink or sometimes transparent. However, when you heat it up again, It will turn back to the dark blue colour as in the case of a dry silica jel bead.