Flextank

[fafrd]

I have not used the skins, my preference is to have the tank topped up to the bung. The tank material is permeable so headspace purging would need to be frequent, especially as the wine gets older than 6 months, it gets more sensitive to oxygen as it ages. My tanks are all considered the faster maturation type, and they seem to work well for heavy reds, I haven't aged anything in the tank more than 12 to 14 months, but that doesn't mean you can't go longer, I try to free up tank space for the next season.

Thanks. I spoke to Flextank and they pretty much said the same thing. Better to fill the tank (even if using skins), need to purge the headspace with inert gas if not, and only about 10% of customers purchase the skins...

So I guess what I'm thinking is going with the smaller 30 g tank and managing the excess in carboys.

Are you noticing the effects of the flex tanks micro oxygenation compared to aging in stainless or glass? What size Flextank are you using?

 

[fafrd]

A friend of mine with a winery has some of the flex tanks with the wide lids. He uses them as variable capacity flex tanks using a standard steel flex tank lid inside it. I don't remember what sizes he has. But it seems to work pretty well.

The 'skins' are made of flexible plastic, is this what you mean by 'standard steel flex tank lid inside it'?

Do you know the minimum fill factor he uses (3/4, 2/3, 1/2, etc)? And how often he purges the headspace?

 

[GreginND]

The 'skins' are made of flexible plastic, is this what you mean by 'standard steel flex tank lid inside it'?

Do you know the minimum fill factor he uses (3/4, 2/3, 1/2, etc)? And how often he purges the headspace?

Sorry, I meant to say VC tank, not flex tank. No, he uses a lid for a stainless steel variable capacity tank. There is no head space to purge.

 

[fafrd]

Sorry, I meant to say VC tank, not flex tank. No, he uses a lid for a stainless steel variable capacity tank. There is no head space to purge.

Got it.

Does he do anything with inert gas to prevent air getting in through the airlock due to temperature fluctuations. I see that MoreWine! sells some kind of rig for the Speidel VC tanks and wonder if that is really necessary.

Also, does he bottle straight out of the VC tank or do any additional maturation such as in oak barrels first?

 

[stickman]

I have 3 of the 30gal tanks, all 3 are full at the moment. I sometimes find that the same wine in a glass carboy may be a bit more fruit forward, but more simple, less length on the finish, possibly less interesting depending on your taste. I usually do a blend after the aging period and then bottle. One of the problems of comparison is the type of oak used, I use large tank staves in the Flex, and often use cubes in the glass carboys, so there is always an expected difference.

 

[fafrd]

I have 3 of the 30gal tanks, all 3 are full at the moment. I sometimes find that the same wine in a glass carboy may be a bit more fruit forward, but more simple, less length on the finish, possibly less interesting depending on your taste. I usually do a blend after the aging period and then bottle. One of the problems of comparison is the type of oak used, I use large tank staves in the Flex, and often use cubes in the glass carboys, so there is always an expected difference.

Thanks. So your batches are always greater than 30 gal and you keep your flex tanks filled and the excess in carboys, right?

Blending is an interesting idea.

How long do you typically age robust reds in your Flex tanks?

And as far as oak, what is the difference you detect between staves and cubes?

Do you remove the staves once desired oakiness is achieved? And as far as cubes/carboys, do you rack off the cubes once target oak is achieved or leave them in through maturation?

Anyway, your experience is a helpful confirmation that the mixroxgenation properties of the Flex Tabks does impact the wine maturity/complexity.

 

[stickman]

I always have some excess wine in carboys, sometimes the carboy survives until the end of aging, other times I'll bottle the carboy early and use for top up after tasting and testing etc.

Most of my heavy reds age in the tank between 6 and 12 months, I don't have any hard rules, I taste along the way and try to bottle once the wine softens a bit, but still has enough of an edge to allow aromatics to recover in the bottle.

I haven't done any controlled experiments to be able to say what the difference is between staves and cubes, my staves have always been from a different manufacturer than the cubes, the wood source, toast levels, and toasting methods, are different. I think that is part of the fun. As I indicated above, I can say the wine aged in the Flex tank with the staves had a longer finish and more complexity, but is it from the tank or from the staves or a combination of the two, I don't really know.

So far I have not removed the oak staves due to reaching a target, they usually stay in until the end. With cubes I discard them during racking if I feel they have been extracted, if the racked wine needs more oak I'll add more cubes.

 

[Stevelaz]

Them flex tanks are pretty interesting. I was just looking at one of these barrels for primary and still using demijohn/carboys for bulk aging. This is a 30 gallon.

 

[fafrd]

Them flex tanks are pretty interesting. I was just looking at one of these barrels for primary and still using demijohn/carboys for bulk aging. This is a 30 gallon.

I used a 55 gallon barrel like that for primary of about 450 lbs. it worked well.

I also used that barrel for 48 hours after press with the lid sealed and with an airlock. Tail-end of primary fermentation was ongoing along with MLF so airlock was bubbling and don't detect of oxidation despite the large surface area of the headspace.

I then tacked off of the gross lees into Carboys and MLF continued to completion.

Those blue barrels are waaaay less expensive than flex tanks but I have two concerns about using them for maturation:

1/ The large surface area of any headspace means they basically need to be maintained completely full (above the brim) and I'm not sure how that will behave in the face of temperature fluctuations.

2/ Flextanks have supposedly been sized to match the Microoxidation levels of 2-year-old oak barrels, but I have no idea what level of micro these will provide except that it will increase with smaller barrel sizes.

I suppose it is really a question for mother thread, but I'd be interested in anyone who has experience with maturation in these blue plastic barrels - is that a viable option?

Also, for anyone with a 30 gallon Flextank, I'd appreciate a swag on sidewall thickness to hazard a guess as to whether a 30-gallon blue barrel will mature faster or slower as far as Microoxidation rate...

 

[Stevelaz]

Yes, there is no way i would use that barrel for bulk storage, only for primary. Last year i borrowed one and put 18 gallons of Chilean juice in it. When it got to about 1.000 i put the lid on with an airlock. The lid does seal air tight, i had nice action in airlock. Then racked into demijohn and carboy a few days later. I really liked doing the primary in one big batch instead of different buckets. This batch really came out good!

 

[fafrd]

Yes, there is no way i would use that barrel for bulk storage, only for primary. Last year i borrowed one and put 18 gallons of Chilean juice in it. When it got to about 1.000 i put the lid on with an airlock. The lid does seal air tight, i had nice action in airlock. Then racked into demijohn and carboy a few days later. I really liked doing the primary in one big batch instead of different buckets. This batch really came out good!

What would be your primary concern with maturation in one of those sealed blue barrels, the speed of Microoxidation or something else?

I spoke to the CEO of Flextank and was told that the thickness of the 50-gallon tank is about 6mm (and about 7mm for the 30-gallon and 8mm for the 15-gallon).

The thickness of those 55-gallon blue barrels is 2.2mm, meaning they should let through oxygen at about 3.6x the rate of a flex tank.

A 15-gallon neutral oak barrel will also introduce oxygen at a faster rate than a 60-gallon oak barrel (about 2.5x based on surface/volume ratio), so are there concerns with fast aging in HDCP barrels that go beyond similar concerns in small neutral oak barrels?

 

[Stevelaz]

Yes oxidation . Wouldn't it not be good to bulk age in that blue barrel due to the head space issue? Im only doing 18 gallons, maybe 24 this year. Even if it was filled close to the top wouldn't there be to much surface area it risk it? However, the friend i borrowed it from last year told me he did a white in it from start to finish. I just didnt think that was a good idea..

 

[fafrd]

Yes oxidation . Wouldn't it not be good to bulk age in that blue barrel due to the head space issue? Im only doing 18 gallons, maybe 24 this year. Even if it was filled close to the top wouldn't there be to much surface area it risk it? However, the friend i borrowed it from last year told me he did a white in it from start to finish. I just didnt think that was a good idea..

got it, thanks. Yes, the barrel would need to be filled so that the wine is touching the white domed lid and the seal would need to keep that wine above the brim from leaking. You would have to top off through the bung hole kind of like you would in an Oak Barrel.

So there may be mechanical/liquid concerns to get the headspace volume and surface down to where it would be in a Flex Tank or other aging vessel, but as far as the faster microxidation trough the thinner sidewalls, I can't think of a reason why it should be worse than aging in a small 15 or 7.5 gallon oak barrel (which is also not advised and more complex to manage, but many winemakers do so anyway).

How did your freind manage headspace in the barrel? How topped-up did he keep it? Up into contact with the lid or below the brim?

 

[Stevelaz]

How did your freind manage headspace in the barrel? How topped-up did he keep it? Up into contact with the lid or below the brim?


I have no clue, i will have to ask him if i see him...

 

[verdot]

How did your freind manage headspace in the barrel? How topped-up did he keep it? Up into contact with the lid or below the brim?

As with barrels, you can drop in any kind of santized non permeable object in to elevate the fluid level. Glass marbles in a mesh bag would work nicely. Flushing the top with argon/co2 would be a solution, as well.