moviez
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Iodine stain damage and iodine storage
Hello, all!
I have a small amount of iodine that I may have mistakenly stored alongside other bottles. While I know iodine tends to stain its surroundings, I
assumed it would be fine since its container was unopened and sealed. However, after just a few months, I noticed that all adjacent bottles had become
stained, even though they were still wrapped in unopened plastic seals.
I’m trying to determine whether the contents inside those bottles could have been contaminated. Has anyone had a similar experience, and if so, were
the contents ultimately unaffected or compromised? I understand there are many professionals here, and I would greatly appreciate any insights you
might share.
Please see the picture of the aftermath.
On a separate note, what’s the best way to store iodine, or I would just have to accept that it would stain its surroundings?
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Radiums Lab
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What substance is there in above bottle? I stored my Iodine in a glass ampoule.
[Edited on 17-8-2025 by Radiums Lab]
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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moviez
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It’s a bottle of ammonium cerium sulfate. In theory, it shouldn’t react with iodine. But I’m thinking if I need to open the bottle and transfer
them to a different container; or worse, purity the reagent.
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Sulaiman
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just fyi, one example
About 232g iodine stored for over 5 years in various climates.
I saw a dusting of tiny iodine crystals around the neck
the tissue shows what came off.
It is an ex-medicine bottle, not perfect, but the cap has not yet corroded
(photographed just after reading the above posts)
even though the paper labels are covered in tape, some of the ink has been oxidised.
I have tried other bottles/caps, this one is the best survivor so far.
I think that I bought 250g about 8 years ago, only used 18g so far 
_____________________________
most iodine deposits slowly evaporate (sublime) away if given ventilation.
I would expect some superficial damage to plastics,
and a very slight porosity to iodine vapour
but unless your reagents are of reference quality I doubt that you would notice.
I would re-bottle. HDPE is great, but certainly not perfect.
(eg both az. sulphuric and az. nitric slowly corrode hdpe)
The shrink-,wrap seems to have absorbed most of the iodine,
I would remove the shrink-wrap and inspect the jar, it looks quite clean.
I would look at the inside of the cap and the top of the jar for indications of iodine.
re-bottling will minimise future doubts.
[Edited on 18-8-2025 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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moviez
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Thank you, Sulaiman, that’s very helpful.
Here’s a photo I just took of the iodine bottle. You can clearly see the stain, even though the bottle is completely sealed and has never been
opened. Perhaps I should transfer them to a medical grade glass bottle like you did. I’m just surprised that within just a few months, the iodine
vapors managed to penetrate multiple layers—from a sealed container, through the plastic wrap, into the sealed wrap of a neighboring
bottle—ultimately staining the other bottle.
Quote: Originally posted by Sulaiman  | About 232g iodine stored for over 5 years in various climates.
I saw a dusting of tiny iodine crystals around the neck
the tissue shows what came off.
It is an ex-medicine bottle, not perfect, but the cap has not yet corroded
(photographed just after reading the above posts)
even though the paper labels are covered in tape, some of the ink has been oxidised.
I have tried other bottles/caps, this one is the best survivor so far.
I think that I bought 250g about 8 years ago, only used 18g so far
_____________________________
most iodine deposits slowly evaporate (sublime) away if given ventilation.
I would expect some superficial damage to plastics,
and a very slight porosity to iodine vapour
but unless your reagents are of reference quality I doubt that you would notice.
I would re-bottle. HDPE is great, but certainly not perfect.
(eg both az. sulphuric and az. nitric slowly corrode hdpe)
The shrink-,wrap seems to have absorbed most of the iodine,
I would remove the shrink-wrap and inspect the jar, it looks quite clean.
I would look at the inside of the cap and the top of the jar for indications of iodine.
re-bottling will minimise future doubts.
[Edited on 18-8-2025 by Sulaiman] |
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Fery
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Cover the I2 package with few layers of Al foil and replace the foil when you observe a corrosion. It works also for Br2, acetyl chloride, SOCl2,
anhydrous AlCl3 and so on. All the lab scale I2 produced (or at least packed) in my country was always packed into ground glass joint jars (decades
ago, now not anymore and everything "fresh" is from abroad) so there are permanent microleaks through the gap in the ground glass joints and I have to
replace the Al foils like once per 3-5 years.
I2 is very nasty even in microleaks, if your storage box has metal hinges, they will corrode - it happened in my job when storing I2 disinfectants
(solutio iodi spirituosa) - the closest hinges corroded severely and further hinges corroded less.
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j_sum1
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I keep a lot of my iodine in ampoules -- various sizes so I can open one most suited to my needs. All of my recovered/recycled iodine is kept this
way.
I also keep some in the container it was bought in. This is prone to leakage and I know I have lost a proportion of it over the years. I keep this
small container in a sealed glass jar with some sodium thiosulfate in the bottom. I find this perfectly adequate for protecting other chems/objects
– even if it does not prevent iodine losses.
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moviez
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Using Aluminum foil as a “sacrificial layer” is indeed a very smart idea. Since you mentioned iodine erodes metals - I had stored my iodine bottle
in a wooden shelf (where it stained adjacent bottles) and I’ve now moved it to a separate plastic storage container. But I’ll inspect the metal
containers nearby.
| Quote: Originally posted by Fery | Cover the I2 package with few layers of Al foil and replace the foil when you observe a corrosion. It works also for Br2, acetyl chloride, SOCl2,
anhydrous AlCl3 and so on. All the lab scale I2 produced (or at least packed) in my country was always packed into ground glass joint jars (decades
ago, now not anymore and everything "fresh" is from abroad) so there are permanent microleaks through the gap in the ground glass joints and I have to
replace the Al foils like once per 3-5 years.
I2 is very nasty even in microleaks, if your storage box has metal hinges, they will corrode - it happened in my job when storing I2 disinfectants
(solutio iodi spirituosa) - the closest hinges corroded severely and further hinges corroded less. |
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Keras
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Keep your iodine under concentrated sulphuric acid? It is said to suppress the tendency of iodine to sublime.
I have a bottle of HF (yes, yes, that’s dumb) that is wrapped inside a plastic package closed by what I call a swan neck, i.e. the upper part of the
package is twisted and crumpled into a sort of big wire, bent and kept tightly closed by a plastic hose clamp. I thought it was impervious, but as the
time went by the nearby glass bottle of toluene eroded. The glass is frozen around the point where the two bottles touched.
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moviez
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I understand ampoules are the best storage method but I don’t have high-temp torch in my house (nor am I good at making ampoules). I’ve now moved
the iodine bottle to a separate storage container, and it was wrapped with many layers of packaging paper. Unfortunately this wouldn’t prevent
iodine from escaping; but it would hopefully prevent it from staining something else. Since iodine stains paper quite easily, I can visually check if
iodine vapor has made its way through.
You had a brilliant suggestion of using sodium thiosulfate. I will try to clean the stains with it. If the stains are superficial it should come off
for the most part. I’ll update later.
| Quote: Originally posted by j_sum1 | I keep a lot of my iodine in ampoules -- various sizes so I can open one most suited to my needs. All of my recovered/recycled iodine is kept this
way.
I also keep some in the container it was bought in. This is prone to leakage and I know I have lost a proportion of it over the years. I keep this
small container in a sealed glass jar with some sodium thiosulfate in the bottom. I find this perfectly adequate for protecting other chems/objects
– even if it does not prevent iodine losses. |
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moviez
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That’s an interesting point. Although, it would make it less convenient to use iodine for home chemist.
I don’t have any HF but I wouldn’t feel surprised that HF vapors escape from sealed containers, too..
| Quote: Originally posted by Keras | Keep your iodine under concentrated sulphuric acid? It is said to suppress the tendency of iodine to sublime.
I have a bottle of HF (yes, yes, that’s dumb) that is wrapped inside a plastic package closed by what I call a swan neck, i.e. the upper part of the
package is twisted and crumpled into a sort of big wire, bent and kept tightly closed by a plastic hose clamp. I thought it was impervious, but as the
time went by the nearby glass bottle of toluene eroded. The glass is frozen around the point where the two bottles touched. |
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chempyre235
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I remember someone once reporting on another SM thread that they kept iodine in the freezer.
[Edit]: I found some examples.
| Quote: |
i store my sublimated iodine (about 1 gram right now) in a vial, in my freezer. storing everything that evaporates or sublimes easily and can escape
containers is best stored at the coldest possible temperature. storing iodine at -20°C lowers its vapor pressure by 2 orders of magnitude versus
ambient temperature (20°C)
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https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
| Quote: |
I store my iodine and H2O2 in our 2nd refrigerator that is in the garage. If I make bromine, I'll probably store that there too, or in the freezer. I
like the idea of storing iodine and bromine inside a 2nd container with some base in it, thanks for that idea Woelen.
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https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
| Quote: |
i keep mine in the freezer. no nasty peroxides and no loss. been 2 years at least
also keep gallium, DCM and iodine (double bottled) with success
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https://www.sciencemadness.org/whisper/viewthread.php?tid=79...
"However beautiful the strategy, you should occasionally look at the results." -Winston Churchill
"I weep at the sight of flaming acetic anhydride." -@Madscientist
"...the elements shall melt with fervent heat..." -2 Peter 3:10
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moviez
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That’s a good point! I don’t have a freezer specifically for chemical storage, but it’s good to know.
| Quote: Originally posted by chempyre235 | I remember someone once reporting on another SM thread that they kept iodine in the freezer.
[Edit]: I found some examples.
| Quote: |
i store my sublimated iodine (about 1 gram right now) in a vial, in my freezer. storing everything that evaporates or sublimes easily and can escape
containers is best stored at the coldest possible temperature. storing iodine at -20°C lowers its vapor pressure by 2 orders of magnitude versus
ambient temperature (20°C)
|
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
| Quote: |
I store my iodine and H2O2 in our 2nd refrigerator that is in the garage. If I make bromine, I'll probably store that there too, or in the freezer. I
like the idea of storing iodine and bromine inside a 2nd container with some base in it, thanks for that idea Woelen.
|
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
| Quote: |
i keep mine in the freezer. no nasty peroxides and no loss. been 2 years at least
also keep gallium, DCM and iodine (double bottled) with success
|
https://www.sciencemadness.org/whisper/viewthread.php?tid=79... |
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moviez
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I opened the plastic wrap and wiped the impacted bottles with dilute sodium thiosulfate solution and then water. It worked really well! See the
attached picture for a comparison.
I wanted to say that sodium thiosulfate works in aftermath cleanup, too!
I also tried to clean the stain with isopropyl alcohol wipes (since iodine dissolves in alcohols as well) but this turned out to be a bad idea. The
isopropyl alcohol dissolved the ink on the label much faster than dissolving iodine stains. Another lesson learned.
| Quote: Originally posted by moviez | I understand ampoules are the best storage method but I don’t have high-temp torch in my house (nor am I good at making ampoules). I’ve now moved
the iodine bottle to a separate storage container, and it was wrapped with many layers of packaging paper. Unfortunately this wouldn’t prevent
iodine from escaping; but it would hopefully prevent it from staining something else. Since iodine stains paper quite easily, I can visually check if
iodine vapor has made its way through.
You had a brilliant suggestion of using sodium thiosulfate. I will try to clean the stains with it. If the stains are superficial it should come off
for the most part. I’ll update later.
| Quote: Originally posted by j_sum1 | I keep a lot of my iodine in ampoules -- various sizes so I can open one most suited to my needs. All of my recovered/recycled iodine is kept this
way.
I also keep some in the container it was bought in. This is prone to leakage and I know I have lost a proportion of it over the years. I keep this
small container in a sealed glass jar with some sodium thiosulfate in the bottom. I find this perfectly adequate for protecting other chems/objects
– even if it does not prevent iodine losses. |
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Sulaiman
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WOW ! nice cleanup job
when I had a lab, sodium thiosulphate solution was one of my 'antidote' chemicals on the shelf immediately behind me when in my usual working
location, for halogens but mostly for silver salts.
I am amazed how nicely you've cleaned it
- I usually have to make a new label.
(ok, in truth, I often just do nothing and live with ugly labels)
CAUTION : Hobby Chemist, not Professional or even Amateur
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j_sum1
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| Quote: Originally posted by Sulaiman | | when I had a lab, sodium thiosulphate solution was one of my 'antidote' chemicals on the shelf immediately behind me when in my usual working
location, for halogens but mostly for silver salts. |
I keep a row of spray bottles near the entrance to my lab. These get used all the time for clean-ups and spills, and other things too.
I have
dilute sodium carbonate – tells me where I have been when I am using lead compounds
dilute sodium thiosulfate – whenever I am working with oxidisers – especially iodine, nitrates, permanganates, and Cr(VI)
dilute hypochlorite solution – only it never seems to work when I need it. The spray nozzle deteriorates too quickly.
methylated spirits – 95% ethanol – good for cleaning, rinsing water droplets off glassware, removing sticky labels and marker pen
deionised water
I also have acetone, dilute HCl, dilute NaOH and dilute HNO3 within easy reach, but not in spray bottles. Directly overhead is a large roll of paper
towels and another of cleaning cloths.
I still never seem to have a tidy lab, but at least I am covered for a range of minor mishaps.
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moviez
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Thank you! I actually took a quick video of cleaning the iodine stain of another bottle. It’s quite satisfying to see how it was cleaned!
| Quote: Originally posted by Sulaiman | when I had a lab, sodium thiosulphate solution was one of my 'antidote' chemicals on the shelf immediately behind me when in my usual working
location, for halogens but mostly for silver salts.
I am amazed how nicely you've cleaned it
- I usually have to make a new label.
(ok, in truth, I often just do nothing and live with ugly labels) |
Attachment: My Movie-360p30.mov (1.7MB)
This file has been downloaded 45 times
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moviez
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That’s very smart to have these spray bottles ready.
I do have a few solutions handy: sodium metabisulfite solution (to clean up chlorate/bromate), sodium thiosulfate (for iodine) and saturated sodium
bicarbonate solution (to clean up any acid spill). I just do relatively simple experiments at home but I can imagine a professional lab would prepare
far more. It never hurts to be overprepared than being sorry!
| Quote: Originally posted by j_sum1 | | Quote: Originally posted by Sulaiman | | when I had a lab, sodium thiosulphate solution was one of my 'antidote' chemicals on the shelf immediately behind me when in my usual working
location, for halogens but mostly for silver salts. |
I keep a row of spray bottles near the entrance to my lab. These get used all the time for clean-ups and spills, and other things too.
I have
dilute sodium carbonate – tells me where I have been when I am using lead compounds
dilute sodium thiosulfate – whenever I am working with oxidisers – especially iodine, nitrates, permanganates, and Cr(VI)
dilute hypochlorite solution – only it never seems to work when I need it. The spray nozzle deteriorates too quickly.
methylated spirits – 95% ethanol – good for cleaning, rinsing water droplets off glassware, removing sticky labels and marker pen
deionised water
I also have acetone, dilute HCl, dilute NaOH and dilute HNO3 within easy reach, but not in spray bottles. Directly overhead is a large roll of paper
towels and another of cleaning cloths.
I still never seem to have a tidy lab, but at least I am covered for a range of minor mishaps. |
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