Iodophor losing colour when used on copper

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Kev888
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Iodophor losing colour when used on copper

Post by Kev888 » Wed Nov 16, 2016 2:30 pm

I recently started using an iodophor disinfectant for the first time. Mine happens to be Evans FAM30, which includes some acid buffers, but I don't think its substantially different to any other acidefied iodophors.

I believe iodophors are safe to use on copper - though would be pleased if someone could correct me if this isn't so. However, I notice that copper causes the solution to lose colour - in extreme cases it can go completely clear. I believe this may be an indicator that the iodine is exhausted and no longer effective, yet it happens with completely unsoiled/unused copper. It is not restricted to weak, no-rinse solutions either; stronger ones at 70ppm iodine go noticeably paler too.

Have other people had this happen and/or know what the cause is or implications are?

Thanks
Kev

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Re: Iodophor losing colour when used on copper

Post by McMullan » Wed Nov 16, 2016 4:29 pm

Iodine reacts with metals and copper is a fairly reactive metal, especially with acids. I don't sanitise any copper, but effective contact time in iodophor solution would be a few minutes, Kev. Can't you heat/boil sterilise the copper?

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Re: Iodophor losing colour when used on copper

Post by Kev888 » Wed Nov 16, 2016 5:28 pm

Thanks, the acid is a very good point. I was a bit surprised that I'd not heard of this happening before, but not all iodophors are acidified so that could explain it. I understand they need to be somewhat acidic to work properly, but on reflection most/many solutions people use may not be hugely so.

I can use other methods - the CFC is the only major copper thing I have, and that gets near-boiling wort sent around it for 30mins in any case. I was just trying the iodophor in addition, but it needs higher concentrations and long contact times to bring much extra kill-power to the table, certainly to get at things like spores. So its probably no-go under the circumstances, and boiling wort alone will have to do.
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Re: Iodophor losing colour when used on copper

Post by Kev888 » Wed Nov 16, 2016 6:28 pm

A bit more searching found this from Vossy about a decade ago:
If you recirc iodophor through copper, be it a cfc or pc it'll decolourise the iodophor solution rapidly :shock:
That's why I got some Saniclean :wink:
So it obviously isn't just me or my product. Of course, back then the effectiveness of starsan on wild yeast was just taken as read (I believe saniclean is pretty much the same technology), whereas it has begun to be questioned these days.
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Re: Iodophor losing colour when used on copper

Post by sladeywadey » Wed Nov 16, 2016 6:58 pm

Interested in the Fam30 product Kev. I'm running low on videne. Is the Evans' stuff better? Also is it no rinse?

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Re: Iodophor losing colour when used on copper

Post by Kev888 » Wed Nov 16, 2016 8:23 pm

I've never used videne so can't draw a first-hand comparison, and am pretty new to the Fam 30 stuff too. However FWIW it seems pretty potent, its got 2.75% w/w (I think thats 27500ppm) available iodine when new, and also contains sulphuric and phosphoric acid - presumably partly as PH buffers.

Apparently (Aleman and Vossy have said) Evans consider it to be safe for drained, no-rinse use at dilutions of 12.5ppm, though it has all sorts of different disinfecting and cleaning applications in farming and dairy industries where it is used at much stronger levels too and then rinsed.

Though the smallest I've seen it packaged is 5L. Thankfully mine (a lucky ebay buy) has over two years to go before the use-by date. I'll probably just about make it, with the odd stronger/rinsed clean now and again.
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Re: Iodophor losing colour when used on copper

Post by sladeywadey » Wed Nov 16, 2016 8:31 pm

Thanks Kev - I might buy some if I can work out the dilution properly - for the thickos amongst us (me!) - what is the safe ml no-rinse usage per litre?

I noticed they also do a Vanodine V18 product in 1 litre bottles which looks similar to the fam30 stuff.

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Re: Iodophor losing colour when used on copper

Post by Kev888 » Wed Nov 16, 2016 9:01 pm

Well you must check this, but I believe that 2.75% w/w equates to 27500ppm available iodine. So for a 12.5ppm no-rinse solution, I calculate that requires a dilution rate of 0.45ml per litre.

At least i hope so, because thats what I've been using! Though also stronger mixes that are rinsed.
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Re: Iodophor losing colour when used on copper

Post by sladeywadey » Wed Nov 16, 2016 9:13 pm

wow only 0.45ml?? how on earth are you accurately measuring that out?

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Re: Iodophor losing colour when used on copper

Post by Kev888 » Wed Nov 16, 2016 9:17 pm

Yes, assuming I'm right anyway. Its quite concentrated, and no-rince levels are pretty wussy really - they use it 'considerably' stronger if they're eradicating something like TB. I have a 1ml syringe for measuring out smaller quantities.
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Re: Iodophor losing colour when used on copper

Post by sladeywadey » Wed Nov 16, 2016 9:31 pm

OK just read that iodine is considered no rinse between 12.5ppm and 25 ppm. So, for the Fam30, 1ml in 2 litres water = 13.8 PPM. Or 3 ml in 5 litres of water = 16.5 ppm.

According to the datasheets, V18 has the same make up as Fam 30 so I think I'll buy a litre of the V18.

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Re: Iodophor losing colour when used on copper

Post by Kev888 » Wed Nov 16, 2016 10:26 pm

V.18 is certainly a more convenient size. I know very little about it, but for some reason thought it was about 2/3rds the strength?
Kev

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