Unfortunately, the wine kits that come with grape juice (such as what we used to make our sav blanc) come with chemicals in the box already. The kits, made by Winexpert (as far as I can tell nobody else makes such a thing) include everything you need to make wine, minus the equipment. I contacted them today to see if their kits are vegetarian, and, alas:
All kits include everything you need to complete the batch - they all have the packages and Isinglass in the box. All the whites contain Isinglass and the reds contain Chitosan.Isinglass is fish bladder, and chitosan is made of the shells of sea creatures such as shrimp. Why are they necessary in wine making? Quite simply, they aren't. Bentonite and sparkalloids make fine alternatives to isinglass, and for the low-tech vintner, gravity will do the trick. These chemicals are fining agents. They are slightly ionized, which allows sediment in the wine to attach to them. These heavy particles eventually sink to the bottom of the carboy (fermenting tank). When the wine is bottled, you simply stop siphoning it out as soon as you get to the sediment, leading to a very transparent wine, like the kind you get from a "real" winery.
Wineries with high tech equipment can also filter the wine, but that is simply not realistic for Jeff and me.
When the weather is nice again, I may take a trip to the Finger Lakes with my parents to tour the vast wineries in the area. While there I will try to ask if it's possible to buy grapes or grape juice from the wineries. I'm not sure if this is something that's done often but it's what the helpful salesperson at the local homebrew store has suggested. Otherwise, unless Jeff and I start growing our own grapes (not likely), we will be sticking with non-grape fruit wine.
As for other wines, how can you tell if the stuff you drink is vegan? Wineries aren't required to list the chemicals they use on the label (except for sulfites, which are present in every wine as a byproduct of fermentation, and are added as well in most cases as a preservative). But there are a few online guides to help you out.