Craft The Perfect Draft - Verdigris Myths

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A while back someone raised a question regarding the use of copper wire in a mash tun build I had posted. They were concerned over the possibility of developing verdigris poisoning by having hot wort come into contact with copper. We've all seen those copper roofs, drains and water lines with a green colored patina on them, the patina is formally known as verdigris. I've never known, or heard of anyone being poisoned by it, even though some sources say coming in contact with large amounts of verdigris can cause nausea and vomiting. The issue isn't with wort coming into contact with copper, that's perfectly fine, the potential for poisoning occurs when verdigris forms on the copper and it comes into contact with your wort. So to some extent the concern seemed to be valid, but I felt the level and causes for concern needed to be explained and understood too.

In my mash tun build I used a braided stainless steel filler connector for the grain filter. I reinforced the inside of the braid with a spiral made from 12 gauge copper wire, to prevent the braid from collapsing under the weight of the wet grain. So after two years of use, brewing at last once a month during that time, I decided to tear down the grain filter and inspect it. I knew that brewers have for centuries referred to their kettle as 'the copper' because kettles were in fact made from copper. I'm pretty sure if their kettles produced poisonous beer there wouldn't as many brewers or beer drinkers around as there are today. Eventually I did come across an article titled Metallurgy For Homebrewers in Brew Your Own Magazine, that explained away a lot of the myth surrounding verdigris and brewing.

"Copper is relatively inert to both wort and beer. With regular use, it will build up a stable oxide layer (dull copper color) that will protect it from any further interaction with the wort. Only minimal cleaning to remove surface grime, hop bits and wort protein is necessary. There is no need to clean copper shiny-bright after every use or before contact with your wort. It is better if the copper is allowed to form a dull copper finish with use." ~ John Palmer November 2007

Once I had the stainless steel braid and copper wire apart it was easy to see that there were no signs at all of any green colored verdigris patina on any of the surfaces. In fact I was relieved to see that the entire copper surface of the reinforcing wire had developed a nice dull copper oxide layer. As for maintaining my mash tun all I had been doing is flushing the grain out with water and then turning it upside down to air dry. I had read of other brewers using white vinegar and salt or StarSan to shine up their copper parts but after doing some research I was convinced this wasn't at all necessary.

After reassembling the grain filter I went on to use that same mash tun for another two years, in fact I eventually built a second mash tun using the same design and haven't had any issues with either of them. I produced some fine beers with those two over the years and even though I've since upgraded to a RIMS brewing setup, I still have them in my brew room. My advice to anyone currently using copper, or planning to include copper in their brewing process is to RDWHAHB and dispel all those verdigris myths.
Vince Feminella [aka: ScrewyBrewer]
[email protected]
I'm not sure the formation of verdigris and the risks of ingesting it are this simple.
Back when I chilled still, I used a homemade copper CFC. Once, after not brewing for a while with it, I flushed it out with warm PBW. The PBW solution came out green. And not just a little green.
Palmer's quote refers to 'regular use' and 'relatively intert', but these aren't strictly defined terms. What is I brew once a month? A few times a year? If I had copper in my brewery still, I'd want to at least keep an eye on it. For that reason, I'd be hesitant to use copper where I couldn't see it.
I use PBW every other brew and have encountered the blue/green-ish PBW solution too (recirculating hot PBW for 30-60 minutes). Apparently, this is just removing the oxidized layer that's mentioned in the article, but after rinsing and running StarSan through the system, the water comes out completely clear, so I think as long as you give things a good rinse etc., you should be fine. Given what I'm hearing here though, I may just skip the PBW wash (for the CFC anyway) and just rinse and sanitize it after brews.
It's worth noting that copper should not be used in anything that touches your beer post fermentation. From the BYO article:
"Copper is a problem post-fermentation because it catalyzes staling reactions, including the production of hydrogen peroxide and can oxidize the alcohols to aldehydes. Finished beer should not be stored in contact with copper, although serving beer with copper tubing in a jockey box should not be a problem, because of the short contact time immediately before serving."
I wouldn't use copper in a jockey box. Post beer anything should be used with SS only due to the acidity of the beer causing oxidation of the copper (if the contact is long enough).
I'd like to suggest another solution...get a better braid so you don't have to use the wire inside. I've used the same braid for nearly 17 years and 475 batches. I've used it with up to 75 lb. of grain and it has never collapsed. If brewers simply get the correct braid, you don't have to mess with putting wire in it.
The problem is copper acetate, which it takes a fair amount to be poisonous, but in general it isnt good for you. I doubt there is enough acetic acid, or a low enough ph, in a standard mash to matter. YMMV.
Why not use a brass or bronze wire and skip the issue? Most alloys are far less reactive. And the wire will have more strength.
@ScrewyBrewer Use Lasco brand (part number 10-0121 or 10-0321). If you can't get it locally you can order it from Amazon.
You can buy a stainless bazooka tube for $6.00 from Amazon/Homebrewstuff.com & never have to worry about it collapsing.
@Denny it was 'just in case', I had a length of Romex cable on the shelf and used it to make the coil. I have to admit that filter has worked perfectly for me over the years and I never had an issue with stuck sparges even when using flaked wheat and no rice hulls.
@ScrewyBrewer I haven't either without the wire! I guess I'm the kinda guy who doesn't bother solving problems I don't have! ;)
I once racked a Scotch Ale that had become Sulferous in the secondary through my racking cane with copper wire inside, I racked twice in 4 days and the Sulfer was gone. I understand that copper takes away the sulfer, then the beer was truly awesome.
Thanks for posting this. some people just need to justify there money on SS i guess. can you do aluminum next, and low lead brass, and PET plastic and etc...