From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Newsgroups: sci.chem
Subject: Re: Redrying silica gel
Date: Sun, 29 Aug 1999 09:27:56 GMT

oligarch@my-deja.com wrote:

>By the way, I don't know if SG can be reactivated in a microwave oven.
>does anyone have that info?

Yes. In fact a good experiment is to take some indicating silica gel,
place it in a humidity chamber until pink, and spread it on a plate in
a microwave, It will clearly show the uneven distribution of heating
as the blue patches appear.

We use an oven at 50C to dry silica gel, just leave it longer (
overnight if spread thinly ). 100C does work quicker ( 1 - 2 hours ),
but if the silica gel is wet the crystals tend to fragment.

     Bruce Hamilton

From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Newsgroups: sci.chem
Subject: Re: Redrying silica gel
Date: Fri, 3 Sep 1999 17:09:06 +1300

In article <37CDA4D3.F4CB1AA4@enteract.com>,
>    Fred Kasner <fkasner@enteract.com> wrote:
>Didn't you ever dry a precipitate on filter paper in an oven when you
>weren't going to ash it? Drying at 105 deg C or 110 deg C is very
>common and safe and the filter paper is almost always paper.

Maybe you have different paper, but here, the paper becomes quite
dry and brittle after being overnight at 110C, so the sachets of
silica gel beads can fracture if moved before they rehumidify.

We've gradually standardised on 40-50C overnight in an air-circulating
oven for drying silica gel, seem to work fine whether in paper sachets
or loose.

Many of the silica gel sachets people bring in to dry these days don't
seem to be paper, but some sort of perforatred fabric material. No idea
if it has the same thermal reistance as paper.

         Bruce Hamilton