Carboy bung slipping out.

Winemaking Talk - Winemaking Forum

Help Support Winemaking Talk - Winemaking Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
It may be the shape of your carboy neck. I've had the exact same problem with 2 of my 12 or so carboys. They are the same no brand 6 gallon size. None of the other carboys do this so I know it's the carboy and not the bung. The sizing is also important. Some glass carboys take a 6.5 stopper and some take a 7. I think the 1 gallon jugs take a 6.5 and the 4L Carlo Rossi jugs take a 6.0. Unlike some here, I like the silicone stoppers more than the gum rubber type, and the silicone hoods are the best.

Anyway, I got tired of the lack of standardization and have basically switched to Stainless kegs in 5 gallon and 15.5 gallon size. And with those, I use exclusively the silicone waterless airlocks.

The only problem I would have with stainless kegs is the same I have with my barrels, you can't see where to stop the racking cane to avoid the sediment. How do you deal with this?
I use this type and what I did was to soak them for a 5 mins +/- in HOT water. Then push them into the carboy and hold them there for a minute. They then will conform better to the shape of the carboy. With Solid bungs, they don't have the ability to deform and adapt to the carboy shape.

I don't use the rubber carboy or solid carboys. Don't need the headaches. Oh and this type of carboy can also be used on a regular wine bottle top too. (Inverted as in the picture on the left.

1630175998863.png 1630176021574.png
The only problem I would have with stainless kegs is the same I have with my barrels, you can't see where to stop the racking cane to avoid the sediment. How do you deal with this?
There are several ways, one is to measure the depth of the container when empty, marking the racking cane.

A less elegant way is to position a smaller container next to the one you're racking into -- watch the tubing where it connects to the cane. When you see sediment, move the end of the tube to the smaller container and stop racking. This way you don't drag sediment into the clear wine. At this point I pour the barrel into the smaller container, move it to an appropriate sized container, and refrigerate to clear as much as it will.
The only problem I would have with stainless kegs is the same I have with my barrels, you can't see where to stop the racking cane to avoid the sediment. How do you deal with this?

It's a real issue even though by the end of the aging period and after 2-3 rackings there is very little sediment left. It does make a difference with white wine. And this year, the final rack before bottling will be into glass, just so I can tell what's there. For red wine, it just has not been an issue.

It's that kegs and sanitary fittings have so many advantages, that it's hard to use anything else.

Here is 60 gallons and a bunch of empties in a small closet.D53930E4-33C2-4C4A-A831-8C973EB0773E.jpeg
Drying the inside of the neck and the bung helps. I have also discovered that two different batches of drilled stoppers from two different orders are not the same. They appeared to be identical and have identical markings, but the stoppers from one batch were softer than the others. The softer ones stayed in fine, but the hard ones kept popping out. Both types are white. So I have started testing my stoppers to see how hard they are. In the future if I am shipped a batch of hard stoppers I will return as defective.
With a clean paper towel, Try cleaning the bung and mouth of the carboy with clear vodka. Let it dry(should be quick), using a new paper towel clean it again. Let it dry and add the bung. They are a pain sometimes, You might have gas left in the carboy pushing on the bung. If room temps are warming it will cause expansion inside the carboy and put pressure on the bung. Just thoughts to consider
I'm sure this is another newbee question, but here it goes. I'm having a problem with the bungs on my carboys slipping out once set. At first I thought it was just that I hadn't wiped all the sanitation solution off before putting it on. I went back and dried the inside neck of the carboy and the bung. I then pushed it in almost level with the carboy mouth. They still worked their way out in short order. I'm certain I have the correct size. They are the solid rubber ones in 6.5. I've had to resort to taping them in but I'd rather not have to do that if I don't need to. So where am I going wrong here group?
Hey if you're interested I'll send you one of our bungs that might help out. Without the oak insert it might compress enough to get a nicer fit in the carboy. I do find drying the neck and the bung does help with keeping it in place but it's still a pain haha

Send me a message with your name/address and I'll send one.
As I understand, silicone is oxygen permiable. It will let O2 through.

Many such statements may be true but may not have a significant impact in practical uses. * Cork is also permeable but the degree of permeability has long been considered quite acceptable. I've been guilty of making similar statements on here and I've been reminded that while some information may be technically true, it is on little to no significance in wine making. One example would be the fine difference between Sanitizing vs Sterilizing tools, containers and to some degree our wine must.
Of greater significance would be the potential for a given material to impart unwanted elements/flavors to our wine. Buytl Rubber for instance is 400 times less permeable to oxygen than silicone but I would NEVER use a rubber stopper in my carboys or any storage container around my wine. (Been there and suffered the consequences) The various acids in our wines: Tartaric acid, Malic acid, Lactic acid, Citric acid each can and do affect some cork materials differently. And of course there both natural and buytl rubber used for corks so ALL of that has to be considered. For that reason it's generally best to purchase such things from reliable sellers of wine supplie and your local wine supply store is only as safe as the knowledge level of the owner/buyer.

Most folks on here who have been making wine for a lot longer than me (6yrs now) can tell you that our wine making process is pretty forgiving in many ways, but there are the occasional stumbling points Silicone bungs are not one of those. I'd worry more about the seal of my airlock in the bung or the potential for atmospheric pressure changes to suck in airlock solutions or push out wine. ( I've had that latter happen several times and I normally keep my 3 gallon carboy filled to within 1 inch of the bottom of the bung.)

* A 500lb bomb will kill a lot more people than a 9mm bullet but which one are you more likely to get killed by in your average American city?
@jjowers , Things like this have been discussed here many times. You’re definitely not the first winemaker to be diagnosed with slippery bung syndrome. Here’s another thread from earlier discussions: Are all airlocks created equal? Though it’s barrel focused, it drifts into the carboy realm as well.
Last edited:
I’ve used the drying both carboy mouth and the bung really well and taping the bung down with electrical tape. The tape is my last resort if I don’t like how it fits. I may try the soaking in hot water next time though.