Desiccant sachets...

[Externet]

Heating these common sachets in an oven for a given amount of time is supposed to make them hygroscopic again,  is that right?

What if in a microwave oven ?  Would it equally work or has to be some specific 'material/formulation' ?  

 

An educated guess would work, as I have no means to confirm its hygroscopy after the 'treatment'

Or, which household product can be used instead, it is to prevent condensation in a 0.25 litre sealed canister with electronics that will be exposed to cold.

Edit: If any moderator can correct the spelling in the title; thanks.

[StringJunky]

I would say give it 2 mins, leave it 2 minutes, then do it again. That should boil it off. I don't think you can overdo it because MWs excite water molecules and if there's no water it'll d0 nothing to the gel. 

Edit: Thinking about it, when you stop seeing steam coming off it would be the right tine to stop.

Edited July 5, 2018 by StringJunky

[swansont]

It may depend on the product. 

[Strange]

7 hours ago, StringJunky said:

I would say give it 2 mins, leave it 2 minutes, then do it again.

If there’s is a visible amount of steam given off, then it is probably a good idea to open the door in between to dissipate it. (Even if it isn’t visible, I guess)

It would be interesting to weigh them before and after to see if there is a significant reduction. 

[StringJunky]

2 hours ago, Strange said:

If there’s is a visible amount of steam given off, then it is probably a good idea to open the door in between to dissipate it. (Even if it isn’t visible, I guess)

It would be interesting to weigh them before and after to see if there is a significant reduction. 

Yeah, that would be a way to do it and opening the door's a good idea.

[swansont]

If you don't let water vapor escape, it's going to go right back into the beads. That's probably an advantage of the conventional oven — the air is going to be dry. It's not enough to get the beads hot, they need to be hot in a dry environment.

[StringJunky]

3 minutes ago, swansont said:

If you don't let water vapor escape, it's going to go right back into the beads. That's probably an advantage of the conventional oven — the air is going to be dry. It's not enough to get the beads hot, they need to be hot in a dry environment.

True.

[swansont]

I've had varying success with this. The material we used in grad school had a color-changing material. Blue/pink, so you could tell when it was time to change it. The looked like small stones. Popped them in the lab oven for several hours and they were good to go. Other stuff looks like shiny transparent beads, and I've had less success with that, but without the color-changing additive, it's harder to be sure. 

[Externet]

Thanks, gentlemen.

Will give it a try.   [The microwave oven option is because it has an exhausting fan to evacuate moisture out;  conventional ovens usually not.]

[swansont]

1 hour ago, Externet said:

Thanks, gentlemen.

Will give it a try.   [The microwave oven option is because it has an exhausting fan to evacuate moisture out;  conventional ovens usually not.]

I suspect that the microwave will never get nearly as dry as a conventional oven at a reasonable temperature (~ 200 ºC).

[J.C.MacSwell]

Has anyo

13 hours ago, StringJunky said:

I would say give it 2 mins, leave it 2 minutes, then do it again. That should boil it off. I don't think you can overdo it because MWs excite water molecules and if there's no water it'll d0 nothing to the gel. 

Edit: Thinking about it, when you stop seeing steam coming off it would be the right tine to stop.

MWs act on more than just water though. Has anyone tried this? I would be cautious starting out.

[StringJunky]

7 minutes ago, J.C.MacSwell said:

Has anyo

MWs act on more than just water though. Has anyone tried this? I would be cautious starting out.

I should have said  the MW band(s) selected for cooking excite water.  Pedant!    They do go sparkly when there's sharp conductive points (metallic or carbonized food)  present. This has been empirically confirmed by myself and the arc can break the glass platters.

Edited July 5, 2018 by StringJunky