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"Biertourist":1ijvo4bn wrote:

"EoinMag":1ijvo4bn wrote:

"RichieH":1ijvo4bn wrote: I take it those are the figures from wildbrews, I seem to remember the plastic figures being closer to the barrel ones. Oh well we all make mistakes. I wonder how much of a difference this would make if the plastic was twice as thick as the standard youngs tub[/quote:1ijvo4bn]

I'm not sure the thickness of the plastic has a lot to do with it's permeability. You're talking at a molecular level that plastic simply allows the O2 molecules through it's structure like air through a net curtain, so I'm sure that thickness is a function of permeability but not all that important as it's still the same "tightness" of plastic (for want of a better word).[/quote:1ijvo4bn]

My guess is that it's actually just the seal of the platic buckets that's the majority of the problem. Wild Brews also quotes "Flextank HDPE Fermenter" and estimates that one of these will diffuse only 20 cc/L/year.

-Just BARELY more than a glass carboy. So I think it's all about the size of the openening and the seal.

I'd imagine that a better bottle would be right around that 20 cc/L/year estimate for that reason, but the better bottle's aren't included in the Wild Brews chart...


Adam[/quote:1ijvo4bn]

Not so sure, it's always the permeability of plastic that's discussed as a negative. I suspect you're looking at a type of plastic there with a tighter molecular weave....man the terminology is so unscientific, but I think it conveys the idea <!-- s:) --><img src="{SMILIES_PATH}/icon_smile.gif" alt="" title="Smile" /><!-- s:) -->

<edit>PET bottles are not advised for long term beer storage either for the same reaosns, look at the oxibarrier bottles that Coopers produce....same idea it's the plastic and not the seals in my opinion.

yes but I don't think you'd want to keep carbonated coopers or anything other than lambic beer long term in wood either!Oxegen is important to aging sour beers, just as with wine, that's why they're the only ones still stored in wood as a rule. I came across the following on a useful lambic page <!-- m --><a class="postlink" href="www.brewery.org/library/LmbicJL0696.html">www.brewery.org/library/LmbicJL0696.html

"The impermeability of glass to gas diffusion is not likely to be as important in lambic- style beer production as it is for other types of beer. As stated before the traditional oak cask is far from absolutely gas impermeable. Also the fact that glass does not allow gas diffusion is made moot by the fact that studies show that in a vessel the majority of gas diffusion occurs through the closure and its sealing surface (i.e. stopper or lid), not the vessel walls (Personal Communication, Nalgene Technical Services)."

not really sure who nalgene technical services are, but one interesting point is that according to the only actual study I have seen (in wildbrews)there is quite a difference in oxygen diffusion in glass carboys depending on the type of stopper they have, which would lead me to believe the above is probably true

&amp;quot;RichieH&amp;quot;:1jexycgx wrote: yes but I don't think you'd want to keep carbonated coopers or anything other than lambic beer long term in wood either!Oxegen is important to aging sour beers, just as with wine, that's why they're the only ones still stored in wood as a rule. I came across the following on a useful lambic page <!-- m --><a class="postlink" href="www.brewery.org/library/LmbicJL0696.html">www.brewery.org/library/LmbicJL0696.html

"The impermeability of glass to gas diffusion is not likely to be as important in lambic- style beer production as it is for other types of beer. As stated before the traditional oak cask is far from absolutely gas impermeable. Also the fact that glass does not allow gas diffusion is made moot by the fact that studies show that in a vessel the majority of gas diffusion occurs through the closure and its sealing surface (i.e. stopper or lid), not the vessel walls (Personal Communication, Nalgene Technical Services)."

not really sure who nalgene technical services are, but one interesting point is that according to the only actual study I have seen (in wildbrews)there is quite a difference in oxygen diffusion in glass carboys depending on the type of stopper they have, which would lead me to believe the above is probably true[/quote:1jexycgx]

Well I'm thinking of a wooden dowel in a stopper like I've seen with the yanks setups, so there would be an amount of permeability afforded.

Furthermore, noted inventer of the sort of brewing 'wisdom' we are dabbling with here, Jamil Zainashef (or whatever) recommends using HDPE in a podcast on lambic and flanders red. There is also testimony here from people who have done it saying it's great. FACT! I'm going to do it, and show all you hombres.

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We do get Duchesse De Bourgogne here. I don't find it that sour, relatively, but you did mention it by name...

A lot of the plastic fermenters are Polypropalene anyway not HDPE, if that makes any difference!