Glavanized steel, wort, and you.

[Pabst Blue Robot]

Before my last brew, I modified my copper lautering manifold with a fine mesh wire screen to assist in preventing stuck sparges. It worked like a charm; I brewed, fermented, and kegged a batch which is now conditioning. Come to find out, however, that the wire mesh was in fact galvanized steel.

From what I understand of the hot dip galvanizing process, there is zinc involved. I understand zinc can be toxic if ingested in certain quantaties, and I'm curious if using a galvanized steel screen in the mash could have leaked zinc into the wort in unhealthy quantaties. I tried a sample when last I checked the gravity and it didn't taste off at all, plus I'm still here kicking...

Should I dump the batch? Is there any chemical test I can do to determine if an unhealthy amount of zinc is present? What really sucks is that I was intending to use the yeast cake for tommorrow's brew. Thoughts?

 

[Yuri_Rage]

I doubt there's enough zinc present to be harmful in one batch, but I'd avoid doing that in the future. Wort is mildly acidic, and zinc readily dissolves in acid, so you probably do have a higher than usual zinc content in your beer.

 

[Pabst Blue Robot]

Thanks for the reply, I will remove the screen before I brew next.

I took a PH reading of a hair under 6 when the wort was in the kettle, pre boil, but I couldn't say how accurate the meter is. (My uncle found it in a brew store years ago, but from the look of it, it's made for gardening) I don't normally modify my water chemistry anyhow.

From all the searching I've done on Google, the only zinc poisoning that I've seen reference to is from welding galvanized metal in a non ventilated area, or swallowing pennies. I realize that galvanized iron pipes were commonplace in older houses as well, but the water would need to be acidic to leech it.

I'm curious why this doesn't happen with copper, as it is another heavy metal that is necessary in small doses but poisonous in large? Perhaps the threshold is a lot higher, or acid does not affect it as readily?

 

[Yuri_Rage]

I'm curious why this doesn't happen with copper, as it is another heavy metal that is necessary in small doses but poisonous in large? Perhaps the threshold is a lot higher, or acid does not affect it as readily?

Copper is much more resistant to acid reactions than zinc. There's a cool demonstration of this with a penny and some hydrochloric acid (AKA muriatic acid that you'll find in the concrete cleaning/etching section of the hardware store). Take the corner of a file and dig a groove in the edge of the penny (just a small nick deep enough to get through the copper - so you can see the silvery zinc underneath). Drop the penny into a glass container of the acid, and leave it overnight. In the morning, you'll find that the zinc has completely dissolved, leaving a copper "foil" penny behind.

 

[casebrew]

Zinc is a neccessary trace element- to you as well as the yeasties. Good for your prostate gland. In fact I've read that some brewers think it is a neccessary addition to wort. I'd worry more about the zinc being totally dissolved, and exposing the iron screen. Iron WILL wreck beer. It's the problem with enameled brew pots- one chip inside and gaaack! it will make your teeth fall out from the vibrations.

 

[Wables]

I had zinc poisoning once - not cool! It was about 13 years ago, and as mentioned above, I was torch cutting galvanized steel. My dad took good care of me, as he had a similar experience 25 years before brazing conduit.

How did the screen look after brewing? If the galvanized coating still looks intact, I'd drink it.

 

[Pimp Juice]

I wouldn't think there would be more zinc then one of those cold ezze cough drops, but I'd avoid future use.

I would say the beer is bad, give it to me and I'll dispose of it properly.

 

[Hopfan]

Definitely don't use that screen again but as Yuri says, probably not enough to do any damage.

Another follow I know started brewing many years ago without any guidance. He and his buddy put their wort into a galvanized trash can to ferment. When his dad found out, he told them to dump it and dont do it again. He said that the wort dissolved all of the zinc off of the can inside.