Silica gel: advice sought

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thirdcrank
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Silica gel: advice sought

Postby thirdcrank » 2 Jan 2019, 3:12pm

I'm looking for a bit of practical advice about silica gel. I've bought a fire-resistant chest to keep some important documents in and users are recommended to use silica gel to stop the contents from getting damp.

As a hoarder, I've accumulated a few of the sachets which have now been kicking about a while. Is there any way of knowing when they have absorbed all they can?

I understand that this stuff can be regenerated by heating. Is that just a matter of bunging them in the oven?

Otherwise, has anybody any recommendations for the packs advertised online eg at Amazon?

kwackers
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Re: Silica gel: advice sought

Postby kwackers » 2 Jan 2019, 3:18pm

You just need to heat them up a little beyond the boiling point of water; 110-120 C is fine. Leave them for half an hour or so.

I keep them and use them all the time to stop stuff rusting in my workshop. Every drawer has a number of sachets of the stuff inside and I never have problems with rust.

(TBH I normally recharge them by sticking them on top of my wife's kiln when she's firing it.)

Never actually bought any so can't say about the stuff Amazon sells.

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Mick F
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Re: Silica gel: advice sought

Postby Mick F » 2 Jan 2019, 3:52pm

Yes, warm it up to dry it out, but it doesn't need to be hot, just warm and dry to remove the dampness accumulated.
Maybe best to have two lots. One dry and ready, the other in use.

We used to have small screw-in units in upper-deck equipment in the RN, and they had a little window to show the state of the dryness with litmus(?) paper through a little window. Blue was dry, and pink was damp.

You unscrewed the unit and screwed in another. We had little ovens heated by a 60w bulb to dry them out.
Mick F. Cornwall

ambodach
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Re: Silica gel: advice sought

Postby ambodach » 2 Jan 2019, 5:26pm

I have a fire resistant box for important documents which is kept on the floor under a chest of drawers in my bedroom. It has been there for some years now and contents get changed/updated as required. My family know where to find it when I snuff it. There has never been the slightest suggestion of damp. I think you are worrying too much on that score.

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mjr
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Re: Silica gel: advice sought

Postby mjr » 2 Jan 2019, 5:54pm

Mick F wrote:We used to have small screw-in units in upper-deck equipment in the RN, and they had a little window to show the state of the dryness with litmus(?) paper through a little window. Blue was dry, and pink was damp.

That's cobalt chloride paper which tests for moisture, not litmus paper which tests acid/alkaline and always has to be slightly damp to work. :-)
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landsurfer
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Re: Silica gel: advice sought

Postby landsurfer » 2 Jan 2019, 6:22pm

Mick F wrote:Yes, warm it up to dry it out, but it doesn't need to be hot, just warm and dry to remove the dampness accumulated.
Maybe best to have two lots. One dry and ready, the other in use.

We used to have small screw-in units in upper-deck equipment in the RN, and they had a little window to show the state of the dryness with litmus(?) paper through a little window. Blue was dry, and pink was damp.

You unscrewed the unit and screwed in another. We had little ovens heated by a 60w bulb to dry them out.


On aircraft and surprisingly, trains, silica gel is used to keep windows dry and also to assist air dryers ... the silica gel is blue and turns pink progressively. Or over night in a Bombardier Voyager !!! :)
Drying out the silica gel is a moot point, it never returns to its original moisture carrying level and drying it is a definite false economy ...
How much energy will you need to dry it against using the same amount of energy to keep the stored item at a low moisture level ?
Too store documents, vacuum is the best environment, in a light free container ..... on the moon .... :)
Or scan and cloud it ... we have ..deeds, insurance, assurance etc ... it will out live us ....
RSF.
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Norman H
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Re: Silica gel: advice sought

Postby Norman H » 2 Jan 2019, 6:47pm

Self indicating silica gel is now available with a more environmentally friendly indicator than the previously used cobalt chloride. Try Googling Envirogel.

For regeneration an electric oven would be a better source of dry heat.

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mjr
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Re: Silica gel: advice sought

Postby mjr » 2 Jan 2019, 7:06pm

Norman H wrote:Self indicating silica gel is now available with a more environmentally friendly indicator than the previously used cobalt chloride. Try Googling Envirogel.

Huh? https://www.cleanlink.com/productwatch/ ... px?id=3332 "Product Type: Paint Remover"

Cobalt chloride is toxic, an allergen and carcinogen, so use gloves to handle and don't eat it or do other silly things, but that's different to environmentally unfriendly, isn't it?
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landsurfer
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Re: Silica gel: advice sought

Postby landsurfer » 2 Jan 2019, 7:13pm

Norman H wrote:Self indicating silica gel is now available with a more environmentally friendly indicator than the previously used cobalt chloride. Try Googling Envirogel.

For regeneration an electric oven would be a better source of dry heat.


Self indicating silica gel was widely available in 1976 .... I know, i was using it on a daily basis on the RAF Nimrod fleet.
RSF.
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Norman H
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Re: Silica gel: advice sought

Postby Norman H » 2 Jan 2019, 7:23pm

mjr wrote:
Norman H wrote:Self indicating silica gel is now available with a more environmentally friendly indicator than the previously used cobalt chloride. Try Googling Envirogel.

Huh? https://www.cleanlink.com/productwatch/ ... px?id=3332 "Product Type: Paint Remover"

Cobalt chloride is toxic, an allergen and carcinogen, so use gloves to handle and don't eat it or do other silly things, but that's different to environmentally unfriendly, isn't it?



There's EnviroGel and there's Envirogel

thirdcrank
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Re: Silica gel: advice sought

Postby thirdcrank » 2 Jan 2019, 7:30pm

I didn't expect this to become controversial.

I've had a fire-resistant chest for something like thirty years and I've had no problems with damp or - touch wood - fire. Unfortunately, I was in scrooge mode when I bought it and went for a smallish one which has been outgrown. The reviews of the replacement which is now on the way say that damp can be a problem. I'm a bit surprised by that but I'm not going to risk it.

For the time being, I think my accumulated stock, hoarded from deliveries of other stuff, will be OK if properly dried out so next time I'm baby sitting, I'll make use of the electric oven.

Above all, thanks for the advice. :D

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mjr
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Re: Silica gel: advice sought

Postby mjr » 2 Jan 2019, 7:34pm

Norman H wrote:There's EnviroGel and there's Envirogel

And when I click through to its material safety data sheet, it gives methyl violet as an ingredient, which is a poison and mutagen. It's probably better than indicator paper because it's smaller amounts of that than of cobalt chloride but still not completely friendly.
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comfortablynumb
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Re: Silica gel: advice sought

Postby comfortablynumb » 2 Jan 2019, 8:35pm

We have found these very good in the wife's car which lives outside. Had them a couple of years and they dry out easily on the storage heater and back in the car for a couple of months or so, should last ages between dry outs for your needs.
https://www.halfords.com/motoring/car-a ... humidifier
Steve.

thirdcrank
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Re: Silica gel: advice sought

Postby thirdcrank » 2 Jan 2019, 9:10pm

Without actually doing a full rummage, I've found a dozen of the small packets which come packed in with stuff the sender wants to keep dry. I'm hoping they will do the trick when they have had a burst in an electric oven.