Explosion?!?!

This evening I decided to mix a pound of melted sugar into my current concrod grape wine I'm working on.

So I melted the sugar, about 2 cups to 1/4 cup water then poured it in to the 5 gallons of already fermenting grape juice. Within three seconds, the wine is bubbling and frothing and spilling out onto my kitchen linoleum. I probably lost 1/3 to a 1/2 of a gallon of must! Any idea what causes this to happen? Any ways to prevent it from happening in the future on additions like this?

hmm, was it still hot? Did you boil it?

Also when did you start fermentation? Why were just pouring it into an already fermenting wine? Unless it was very early in the process you risk oxidation anytime you pour into or out of your carboy.

You agitated the must, this released a lot of co2 at once, causing the uprushing of brew. Or at least that is my guess.

Yes, the sugar mixture was still hot. No longer boiling, but I didn't want to risk the chance of contamination. It cooled for a few minutes and in it went.

The fermentation started Friday night. This is supposed to be a huge wine, 80 percent juice and juice extract with 20 percent sugar with hopefully an ABV of 15 or 16 percent then aged a year or three. I'm newer to wines, so I figured I'd do as I've done in home brewing with big beers and step the sugar and juice concentrate additions over a few days to make sure my yeast stays happy and healthy.

Maybe it was the super hot sugar that did it. I've got one last addition here in a few days, I'll try it a bit cooler and see if it still does the same thing.

Yeah, I would go with cooling it down first, you should be fine since you just started it friday.

The sugar might not have all been in or stayed in solution, providing nucleation sites for the CO2 in the wine.

ChshreCat said:

The sugar might not have all been in or stayed in solution, providing nucleation sites for the CO2 in the wine.

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+1 This is the likely explanation. Any time you add anything that has any solids associated with it to an active fermentation, the result is a "wine volcano". It's very important to make sure that anything you add is completely liquified.

Hot liquid will force CO2 out of solution as it mixes.