Potable paint?

[Naich]

I'm making a fermenter immersion cooler - the idea being that I can then control the fermentation temperature and do lagers in summer. Basically, it's going to be a sheet of copper, immersed in the wort and cooled with a peltier cooler. Obviously I don't want the copper to come into contact with the wort, so I'm thinking of painting it. Anyone come across a good potable paint?

I had a search and found this, which seems to be right - it conforms to BS3416 which looks to me as if it'll be safe, but I thought I'd double check in case I was about to poison myself.

The other option is to put it in a plastic bag. Has anyone tried anything like this before?

[boingy]

Yeah, that stuff is what you use to coat the insides of drinking water tanks on boats.
Give it a good few days to fully cure then soak it in several changes of water to get rid of any chemical taint before you use it proper.

Not sure I like the idea of ain immersed cooling coil during frementation though. It sounds like just one more potential source of infection. Have you considered standing the FV in a water bath and cooling the water instead?

[steve_flack]

What's the problem with copper?

[Naich]

It's not ideal, but as long as there aren't too many nooks and crannies to harbour nasties, it should be fairly simple to steralise. The trouble is that I'm really limited in the amount of space I can use and this is the smallest way of doing it, with basically just a heatsink and fan sitting on top of the FV (and a PC power supply humming away in the corner). Another way to do it would be to run pipes round the outside and circulate cooling water, but then you need pumps and pipes and other gubbins. Ideally I'd have a fridge for it to sit in, but that is totally out of the question.

Ultimately I need a bigger house, or a house with a bigger garden but I can't see the wife accepting beer making as an excuse to move. Totally unreasonable

[Naich]

What's the problem with copper?

Unless I'm mistaken, the acidity of the wort would eat away the copper, poisoning anyone who drunk the beer and, more importantly, harming the yeast. I'm using copper for its thermal properties, as being the best conductor of heat other than silver. Stainless is very bad at conducting heat, otherwise I could use that. Aluminium has about 1/2 the thermal conductance of copper and is cheaper and easier to machine, but would also be eroded and is more difficult to coat with paint - you need an etching primer to remove the oxide layer.

[Tony01]

I always thought that copper was a no-no for fermentation or after as it can produce copper sulphide in the beer. I've been searching for this and hope this is the right one.

I'd love to hear that this is a b'llcks though!

http://thebrewingnetwork.com/shows/Brew ... -Your-Beer

[steve_flack]

That many breweries use brew kettles made of copper (hence the name 'copper' for that vessel) doesn't change your mind?

[Tony01]

I thought the 'copper' was the boiler????

[steve_flack]

It is. But goes to show it doesn't dissolve much in beer. Copper does react with H2S to form Copper Sulfide but that's insoluble and mostly end up at the bottom of the fermenter. Free hydrogen sulfide isn't exactly non-toxic either being approximately as lethal as hydrogen cyanide.

[Tony01]

Its good to hear then, as I said, I'd like to find out that it is b'llcks!

[Scooby]

I try to avoid copper post ferment due to the long contact time, maybe 10-14 days isn't long but it's longer than the few hours wort is in a copper.

Stainless may be a poor conductor but my old ss loop and python line controlled the fv temp very well and to a tight tolerance. When it came to crash cooling it was very very rapid, far quicker than turning a fridge from 18c - 0c and waiting for the contents to chill down.

I clean and then sanitise the the loop with starsan and just to be on the safe side flame it. I don't think anyone who uses probes, loops or coils immersed in the fermenting wort has had problems with infections.

[steve_flack]

The main risk of copper post-boil IMO is that copper promotes some staling reactions. Whether or not that's a concern when yeast is present to reverse many of those effects is another matter. When you consider contact times you have to also consider temperature and that reactions take place approximate twice as fast if you increase the temperature by each 10C - so a reaction that takes an hour at 100C takes 2 to the power 8 (256 hours - about 10 days) to occur at 20C.

[boingy]

Don't forget that you are planning to coat the copper with a fairly thick layer of bitumen. That will knacker the overall heat conductivity. I suspect stainless will be better than bitumen coated copper so go for stainless if that is an option.

[crookedeyeboy]

Funny one this as I got a phone call from a brewer in France and he is making a copper coil to go in the fermenter for summer. He mentioned that alot of German breweries have either a fermenter made of copper or an immersion cooler made of copper. There are many craft breweries/brewpubs that have copper fermenters too.
Cant be that bad.

[Scooby]

The main risk of copper post-boil IMO is that copper promotes some staling reactions. Whether or not that's a concern when yeast is present to reverse many of those effects is another matter. When you consider contact times you have to also consider temperature and that reactions take place approximate twice as fast if you increase the temperature by each 10C - so a reaction that takes an hour at 100C takes 2 to the power 8 (256 hours - about 10 days) to occur at 20C.

That's true but what about the low ph and the effect of Co2. I did say I wouldn't use copper post fermentation but having listened to this by John Palmer and Jamil Zainisheff where they mention those two things as a reason to avoid copper post boil I'm glad I use a stainless coil.