Black Mould? on the top sides of the fermenter

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Mattpc
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Black Mould? on the top sides of the fermenter

Post by Mattpc » Mon Jun 18, 2018 9:02 pm

Just used my SS Brewtech Brewbucket for the first time. When I opened the lid to transfer the wort I noticed that on the top sides of the fermenter where the scum from the fermentation collects in a brownish colour, the edges were actually black. Rubbing my finger around that area, it came back black. Is it simply a case of a little mould collecting that I don't need to worry about or is it something more sinister? There were no off smells from the beer and it tasted normal out of the fermenter. Prior to using the new stainless steel fermenter it was washed to hopefully remove anything left from the manufacturing and then cleaned and sanitised as normal. I'm not mega fussy about keeping the fermentation fridge absolutely gleaming though I must admit. Any pointers would be appreciated. I suspect actually I've produced beers with this mould on the side before and never noticed because I used to use the plastic wine fermenters with the narrow tops.

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Re: Black Mould? on the top sides of the fermenter

Post by Eric » Mon Jun 18, 2018 9:42 pm

It does seem likely that black mould has settled into the yeast. Fridges are perfect candidates to harbour moulds and should be regularly cleaned and disinfected. Always keep the door open when not in use.

It is possible the beer might not be adversely affected, but I wouldn't harvest the yeast if that was your intention.

Give everything a jolly good clean and sanitising then store them in a clean, dry and dustfree area until required when they should be again sanitised.

Fingers crossed the beer will be fine.
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Re: Black Mould? on the top sides of the fermenter

Post by keith1664 » Mon Jun 18, 2018 9:57 pm

My stainless conicals had a black ring the first time I used them, I've no idea what it was though.
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Re: Black Mould? on the top sides of the fermenter

Post by chefgage » Tue Jun 19, 2018 9:15 am

I seem to think my stainless conical fermenter sometimes has a ring of very dark brown or black substance around the top. I take this to be when it first starts to ferment it is very vigerous so a deposit of krausen gets left in a ring as the fermentation calms down and the level of krausen drops. This then drys slightly and turns a dark colour.

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Re: Black Mould? on the top sides of the fermenter

Post by Kev888 » Wed Jun 20, 2018 11:54 pm

keith1664 wrote:
Mon Jun 18, 2018 9:57 pm
My stainless conicals had a black ring the first time I used them, I've no idea what it was though.
Mine too, I thought at first it was an infection but thankfully thats 'very' rare for me, and the FV had no previous organic contents so it seemed a bit odd. Subsequently, there were no detectable effects whatsoever in the beer (even after many months in the keg) and it never happened again, so I now think it was just inorganic residue of some kind.

The fermenter had been soaked with hot PBW (and disinfected with both acidified iodaphore and starsan) beforehand, but I now believe this didn't get everything. It was suggested to me that hop oils are quite good at liberating gunk that may have been left for the first brew.
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Re: Black Mould? on the top sides of the fermenter

Post by barneey » Thu Jun 21, 2018 7:24 am

Like Kev,

NEW stainless = black ring in FV if thing isn't clean thoroughly before use. Subsequent brews = no problem

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Re: Black Mould? on the top sides of the fermenter

Post by Jocky » Thu Jun 21, 2018 9:20 pm

barneey wrote:
Thu Jun 21, 2018 7:24 am
Like Kev,

NEW stainless = black ring in FV if thing isn't clean thoroughly before use. Subsequent brews = no problem
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Re: Black Mould? on the top sides of the fermenter

Post by Mattpc » Sat Jun 23, 2018 4:09 pm

Seems to be a very common issue. I’ve got another brew in there now so it will be interesting to see what happens..


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Re: Black Mould? on the top sides of the fermenter

Post by Kingfisher4 » Fri Mar 01, 2019 2:50 pm

My new GF SS Conical FV just arrived. Some work yet before it will be ready for the first brew, but I remembered this thread and think I have come across this black / dark brown issue being attributed to manufacturing oils etc preventing full corrosion resistance of the stainless steel, presumably accounting for the intermittent or only initial problem.

A suggestion elsewhere is that in addition to rigorous cleaning before 1st use "passivation" with a mild acidic solution can effectively stop the problem and optimally condition the new SS kit.

Is this true and if so any experience with the best method?

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Re: Black Mould? on the top sides of the fermenter

Post by orlando » Sat Mar 02, 2019 8:00 am

It's something you should consider doing from time to time and is relatively simple. One option is to use “Bar Keeper’s Friend”, which is a stainless cleaning agent containing oxalic acid. It works well on stainless, but don’t use it if you have electronic etching as it will fade or even remove the etching. Add just enough water to form a thick paste and apply the paste to the item you want to passivate. Let it sit on the metal for 5-10 minutes and then gently rub it off and dry with a towel. Alternately you can rinse with clean water, but you should immediately dry it with a towel so the metal gets quickly exposed to air and not water. There is a liquid version too, so if you don't have any at all I suggest buying that.
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Re: Black Mould? on the top sides of the fermenter

Post by Kev888 » Sat Mar 02, 2019 2:37 pm

I'm pretty sure now that the initial black ring is the action of the wort essentially cleaning the stainless, at which is is especially effective if well hopped. So yes a particularly deep clean before use will reduce that, and I would also then passivate before first use as Orlando says. It is hard to know quite how thoroughly things have been done during manufacture, but the residue suggests that it might be wise to 'make sure'.

Subsequently, it kind of depends on your usage. Stainless will passivate itself to a degree, if left dry and in air for fairly long periods (more like days/weeks than hours). But there are limits, so especially if it is used more continuously and/or if it picks up scratches then a periodic passivation is probably sensible.

As you will know, stainless has iron in it and so even high quality grades can rust if any of this gets exposed at the surface; contrary to some web folk-law it isn't just cheapo Chinese stainless at all, though lesser grades are more prone to it. This may occur through things like scratching or other damage, or steel particles from manufacturing tools being left there. Passivation is intended to remove them and allow the passive oxide layer at the surface instead.
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Re: Black Mould? on the top sides of the fermenter

Post by Kingfisher4 » Sun Mar 03, 2019 4:37 pm

orlando wrote:
Sat Mar 02, 2019 8:00 am
It's something you should consider doing from time to time and is relatively simple. One option is to use “Bar Keeper’s Friend”, which is a stainless cleaning agent containing oxalic acid. It works well on stainless, but don’t use it if you have electronic etching as it will fade or even remove the etching. Add just enough water to form a thick paste and apply the paste to the item you want to passivate. Let it sit on the metal for 5-10 minutes and then gently rub it off and dry with a towel. Alternately you can rinse with clean water, but you should immediately dry it with a towel so the metal gets quickly exposed to air and not water. There is a liquid version too, so if you don't have any at all I suggest buying that.
Thanks, will get hold of some. The powder and "cream" seem readily available in the UK but not the liquid ( I assume the foaming / added perfumed spray bottle is not the best choice) I guess the cream may be the best and potentially least abrasive??
Is that the product type mostly used here?

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Re: Black Mould? on the top sides of the fermenter

Post by orlando » Sun Mar 03, 2019 4:53 pm

Cream is fine.
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Re: Black Mould? on the top sides of the fermenter

Post by Kingfisher4 » Sun Mar 17, 2019 5:05 pm

orlando wrote:
Sun Mar 03, 2019 4:53 pm
Cream is fine.
Wow, the cream was great for my Grainfather. Despite thorough cleaning with PBW after every brew there was a slight discoloured residual film. Totally gone after Barkeepers friend during clean up today.

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Re: Black Mould? on the top sides of the fermenter

Post by orlando » Sun Mar 17, 2019 10:46 pm

Kingfisher4 wrote:
Sun Mar 17, 2019 5:05 pm
orlando wrote:
Sun Mar 03, 2019 4:53 pm
Cream is fine.
Wow, the cream was great for my Grainfather. Despite thorough cleaning with PBW after every brew there was a slight discoloured residual film. Totally gone after Barkeepers friend during clean up today.
:wink: The bonus is it is now re passivated too.
I am "The Little Red Brooster"

Fermenting: Someone Somewhere In Summertime
Conditioning: Peaches, Reasons To Be Beerful
Drinking: From Russia With Love (RIS), Summer Sunshine

Up Next:
Planning: Summer drinking Beer.

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