Carboy Mystery Stain
- mumblecrunch
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Carboy Mystery Stain
So I picked up a 5g carboy a couple of weeks ago for free due to a weird stain. The person who gave me the carboy had no idea what it was because he inherited it as-was from someone else.
I've given it all I can with short and long treatments of Oxyclean, PBW, and a fairly concentrated StarSan solution, and the heaviest brushing I can manage. Whatever it is it's not going away. Doesn't budge in the least.
In some light it looks like any old stain; it was definitely a liquid once based on the drops and splotches. But get the light just right and suddenly it gives off a purple and green glow.
I'm not putting anything I want to drink into this thing unless I can get rid of the stain and I've probably already put way more effort in than the $25 I would pay for a new 5g carboy. But now I'm really curious as to what it could be.
Anyone have any ideas what kind of substance can adhere to glass, "glow" purple and green, and withstand heavy hits with both alkali cleaners and acid?
I've given it all I can with short and long treatments of Oxyclean, PBW, and a fairly concentrated StarSan solution, and the heaviest brushing I can manage. Whatever it is it's not going away. Doesn't budge in the least.
In some light it looks like any old stain; it was definitely a liquid once based on the drops and splotches. But get the light just right and suddenly it gives off a purple and green glow.
I'm not putting anything I want to drink into this thing unless I can get rid of the stain and I've probably already put way more effort in than the $25 I would pay for a new 5g carboy. But now I'm really curious as to what it could be.
Anyone have any ideas what kind of substance can adhere to glass, "glow" purple and green, and withstand heavy hits with both alkali cleaners and acid?
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- GuingesRock
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Re: Carboy Mystery Stain
I googled and green/magenta artefacts (the actual term for the problem), green and purple also seems to be a thing, are a common issue with camera lenses. It may be a defect in the glass causing it to reflect light in that way, or there might be something stuck on the inside which is reflecting the light back. It looks like the green/purple colour is a feature of light passing through glass, and so that doesn’t give any clues about the stain. Could it be some kind of lacquer? Would it be worth trying nail polish remover, or paint remover?
https://www.google.ca/#q=green%2Fmagenta+artifacts" onclick="window.open(this.href);return false;
https://www.google.ca/#q=green%2Fmagenta+artifacts" onclick="window.open(this.href);return false;
-Mark
2nd place, Canadian Brewer of the Year, 2015
101 awards won for beers designed and brewed.
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2nd place, Canadian Brewer of the Year, 2015
101 awards won for beers designed and brewed.
Cicerone Program - Certified Beer Server
- mumblecrunch
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Re: Carboy Mystery Stain
There's very definitely a stain on the inside of the glass; in most lighting it looks almost like soap scum on a glass shower door. Based on the pattern it would seem that something dried in the carboy while it was sitting on its side. But get the right light on it and you get the green/magenta thing happening. So I guess it could be that the purple/magenta is less about the stain and more about what happens to that particular glass when something affects its refractive index?
I'm pretty convinced it's an organic stain, but what to clean it with? It can't possibly be safe to use acetone or turpentine or a similar solvent in a container I intend to put beer in. Can it?
I'm pretty convinced it's an organic stain, but what to clean it with? It can't possibly be safe to use acetone or turpentine or a similar solvent in a container I intend to put beer in. Can it?
- GuingesRock
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Re: Carboy Mystery Stain
A soak in H2O2 maybe, can buy bottles of it from the drug store ...apart from that I'm out of ideas.
-Mark
2nd place, Canadian Brewer of the Year, 2015
101 awards won for beers designed and brewed.
Cicerone Program - Certified Beer Server
2nd place, Canadian Brewer of the Year, 2015
101 awards won for beers designed and brewed.
Cicerone Program - Certified Beer Server
- mumblecrunch
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Re: Carboy Mystery Stain
Probably worth a shot.GuingesRock wrote:A soak in H2O2 maybe, can buy bottles of it from the drug store ...apart from that I'm out of ideas.
I've actually found a reference to "food-grade acetone" on-line this morning, but there's a significant cognitive dissonance going on in my head at the very notion of such a thing.
I may also look into trying to get a food-safe d-limonene solvent and see whether that works. I should probably just kick the darn thing to the curb, but it would seem like a waste.
- GAM
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Re: Carboy Mystery Stain
Make a 4l batch on the stove top and ferment in carboy on this side. Turn up right and bottle. Taste it and see if it is off.
Sandy
Sandy
- GuingesRock
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Re: Carboy Mystery Stain
Life is too short .............to let something like that get the better of you. We have to sort this caboy out.mumblecrunch wrote: I should probably just kick the darn thing to the curb, but it would seem like a waste.
I mentioned H2O2 when you said you thought it was organic, because they use it in my wife's lab. She said H2O2 eats volatiles that adhere to glassware.
-Mark
2nd place, Canadian Brewer of the Year, 2015
101 awards won for beers designed and brewed.
Cicerone Program - Certified Beer Server
2nd place, Canadian Brewer of the Year, 2015
101 awards won for beers designed and brewed.
Cicerone Program - Certified Beer Server
- mr x
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Re: Carboy Mystery Stain
Yes and no...I've been occasionally disappointed in H2O2 when trying to clean carboys. I always start with hot caustic now.
At Alexander Keith's we follow the recipes first developed by the great brewmaster to the absolute letter. 

- GillettBreweryCnslt
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Re: Carboy Mystery Stain
I used to work in a chemistry lab and we had to battle glassware stains that would defeat 99% of cleaners. The solution was always a dilute boric, hydrochloric or sulfuric acid solution. I'm just mentioning this as it's the end game. I'd try other things before I went looking for lab grade acids, cause they are the things that will actually dissolve your skin faster then you can rinse it off. But they work 100% of the time. There is a lot of literature online regarding cleaning chemistry glassware, which for obvious reasons needs to be 100% clean for experimentation to be successful.
- mumblecrunch
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Re: Carboy Mystery Stain
mr x wrote:I always start with hot caustic now.
I think I will offer up the carboy to the next challenger (or recycling) before I resort to either caustic soda or lab-grade acids. Caustic is fine if you've got a closed system you can pump it through, but I look at how much Oxyclean, PBW, StarSan and water I generally splash around the kitchen when I'm cleaning a carboy and I suspect I am not the guy for the job if it comes to thatEverwoodAveBrewShop wrote:The solution was always a dilute boric, hydrochloric or sulfuric acid solution.

I worked sanitation at an ice cream factory one summer in my mid-twenties. I got to see some pretty cool cleaning products and techniques. 98% of everything in that place was cleaned with either pumped caustic or heavy-foaming sprayed-on alkali cleaners followed by a light acid sanitizer (sound familiar?). The other 2% usually called for the sulfuric acid. And the rubber gloves you can barely move your fingers in. And the respirator. And, if you were lucky, not contravening any factory regulations or labour laws regarding safety. If you put the heavy acid in a foamer undiluted and sprayed it at high-pressure you could take a layer of almost anything off almost anything. Not that you would ever do that; you especially wouldn't do it because your foreman indicated on your second-to-last day that failing to do so might cause difficulties in securing your final paycheque... Good times.
- akr71
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Re: Carboy Mystery Stain
I'm with Sandy on this. Give it a run before you give up on the carboy. Just cuz the glass is stained, doesn't mean it will affect your beer.GAM wrote:Make a 4l batch on the stove top and ferment in carboy on this side. Turn up right and bottle. Taste it and see if it is off.
Sandy
Andy
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"Now son, you don't want to drink beer. That's for Daddies, and kids with fake IDs." - Homer J. Simpson
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