Moldy corks after storing wine on their sides

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pandakatelyn

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I kept some bottles (ranging from dec '20 to march '21) on a wine rack in my dining room, and popped open one today to discover mold on the cork. 3 other bottles were also molding. I use star-san sanitizer and am immaculate about cleaning. How do i prevent this? Was it because I stored them on their sides? The corks themselves? I'm kicking myself because now I have to dump 10 bottles.
 

crushday

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A couple of questions:

1. Did you make this wine or is it commercial?
a. If you made the wine, then question #2...
2. When you bottled it, did you let the cork ”seat” by storing upright for 2-3 days before laying the bottles down?

Either way...

3. What’s the temp of your dining room? I suspect the real culprit is ambient temperature warming the wine in the bottles, which causes it to expand. The now expanded wine has nowhere to go and will find the path of least resistance. Small amounts of wine are exiting the bottle around the cork and molding under the cap, which is a low light environment - perfect for mold.

And, I think dumping the bottles is not necessary. Mold entering the bottle is a near impossibility, IMHO. Clean them up and drink the wine...
 

pandakatelyn

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A couple of questions:

1. Did you make this wine or is it commercial?
a. If you made the wine, then question #2...
2. When you bottled it, did you let the cork ”seat” by storing upright for 2-3 days before laying the bottles down?

Either way...

3. What’s the temp of your dining room? I suspect the real culprit is ambient temperature warming the wine in the bottles, which causes it to expand. The now expanded wine has nowhere to go and will find the path of least resistance. Small amounts of wine are exiting the bottle around the cork and molding under the cap, which is a low light environment - perfect for mold.
I made it, and let it sit upright for 5 days before storing laying down. The ambient temp is usually around 67-70. I also use heat-shrink capsules on my bottles.
 

crushday

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How much head room do you have between the wine and the cork? I still suspect expansion and contraction from ambient temperatures.

You probably do this too... After I bottle, I store upright for a couple of days and wash/rinse the filled bottles before capping and labeling.

And, I think dumping the bottles is not necessary. Mold entering the bottle is a near impossibility, IMHO. Clean them up and drink the wine...
 

crushday

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And, your corks - are they size #7, #8 or #9? #7s are going to allow more ‘blow by‘ than both #8 and #9, the latter being less susceptible.
 

pandakatelyn

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How much head room do you have between the wine and the cork? I still suspect expansion and contraction from ambient temperatures.

You probably do this too... After I bottle, I store upright for a couple of days and wash/rinse the filled bottles before capping and labeling.

And, I think dumping the bottles is not necessary. Mold entering the bottle is a near impossibility, IMHO. Clean them up and drink the wine...
I leave quite a bit of space, I think. I usually spray everyone down with a star-san mixture and dry before capping. This is one of the bottles I've had since Jan. One of my dragonsblood was a goner, it had a mold bit floating in it. I'm wondering if its the corks, since I tried a new brand this time around from amazon.
 

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crushday

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Wow. I see what you mean now. There’s a couple firsts for me in your images:

1. The agglomerated corks have very large bits and pieces.
2. I’ve never seen mold visually embedded in the cork.

Without a doubt, it’s the corks. Because of the size of the pieces making up the cork, there’s undoubtedly lots of space for mold to hide.
 

pandakatelyn

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Wow. I see what you mean now. There’s a couple firsts for me in your images:

1. The agglomerated corks have very large bits and pieces.
2. I’ve never seen mold visually embedded in the cork.

Without a doubt, it’s the corks. Because of the size of the pieces making up the cork, there’s undoubtedly lots of space for mold to hide.
That was my suspicion! I had just started to use these corks. Time to chuck 'em and start again.
 

MiBor

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I started using synthetic corks exclusively (Nomacorc only) after a couple of embarrassing events when friends I gave wine to said my wine was awful. I managed to find that the problem was the corks I used that year after uncorking about 20 bottles and finding 3 that smelled bad. I don't like the look of the 1.5 inch synthetic corks, but I managed to find #9 Nomacorc in 1.75" length and I never looked back. I know that a wine bottle looks more classy with a natural cork, but I don't want to worry about wine going bad in the bottle again. Plus I can store the bottles upright without fear of corks drying out.
Here is a link, in case you want to check them out:
WINE CORKS 100 SYNTHETIC NOMACORC SELECT 900 WOOD GRAIN FINISH #9 1-3/4″ 22mmX44mm Champfered - Hobby Homebrew
 

bstnh1

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I've used the bi-disc corks from Widgetco for years with no issues at at. I've recently started using Nomacorc just for the convenience of being able to store them upright. I have always used No 9 corks. My take on Amazon - there are a lot of bogus items and other junk being sold on Amazon. There are companies who refuse to sell on Amazon and will not honor a warranty if their product was bought there. I think you'd be safer getting your corks from any brew shop.
 

Rice_Guy

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For mold to grow it requires 1) oxygen, 2) humidity, 3) food source 4) mold spores

* You mention shrink caps which trap humidity. If the caps are removed the problem should go away
* you are using natural cork which leaks (inward rated 4 to 8 mg oxygen per year) why not use synthetic corks which are tighter? and prevent egress or ingress and eliminate both humidity and food source
 

winemaker81

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@pandakatelyn, I've been using Nomacorcs for about 3 years, the Select 900 1.5", and really like them. I had mold problems on the outside of the cork -- it's not dangerous, but it's very unsightly and makes an instantaneous bad impression. Nomacorcs solved that problem.

From what I gathered from the Nomacorc fact sheet and other sources, the Select 900 should be good for 5+ years, and they are the most common model I've found.

This thread has a lot of information regarding Nomacorcs. Some folks report synthetic corks getting creased by Portuguese floor corkers -- I suggest buying a small bag and seeing how yours works.

Personally, I don't use #8's, as I've had leakage in the past. The inside diameter of bottles is not uniform, and IME #9's have worked in all standard wine bottles.

Also, corking screwcap bottles is hazardous. The neck is not designed to handle the stress of corking, and bottles may shatter, so use only corkable bottles.
 

Raptor99

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I use natural corks and I soak them in Kmeta sanitizing solution for 15 minutes before inserting. That softens them up and also sanitizes the corks.
 

stickman

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In 30yrs I haven't seen mold on corks like that. The wine should not soak into the cork a third of the way to the top in less than a year. There are disturbing reports of arts & crafts corks being sold on Amazon as "wine grade", buyer beware applies more now than ever, stick with reputable suppliers for best results.
 

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