About 20 years ago, I was really into home brews. I would just take whatever sugary liquid, and add yeast. My success was generally hit and miss. I found out you can ferment just about anything. Whether you should is another matter entirely. Anyways, I especially liked the classics. Mead is the simplest to make, and the one I seemed to have the most successes with. You just take honey + water (hydromel is what this is called, for you brewing purists). Then you add yeast. You don't even have to add spices, believe it or not. In any event, I found this one old recipe from an old English cookbook. It said simply take hydromel and spices, stop it up in a stone vessel. And bottle it when it stops hissing. I didn't have a stone vessel. So I put it in a bottle in my hot attic. Anyways, unlike most recipes, it didn't call for yeast. The natural yeast would suffice. And I did give it a good long time to ferment that way. Only thing is, I never got Mead from the procedure. And it ended up getting moldy, so I just had to throw it out. What did I do wrong? BTW, I have a couple of other questions about my home brewing experience. So rather than start a new thread, I will just tack them on to this one. There is one home brew called Mountain Wine. You basically steep shredded raisins in water (producing a liquid not unlike prune juice). Then you add sage, and ferment with yeast. Anyone ever hear of this? And where could you simply buy it, online for example, short of having to make it? There also is this other home brew called cock-ale: "Take 10 gallons of ale and a large cock, the older the better; parboil the cock, flay him, and stamp him in a stone mortar until his bones are broken (you must gut him when you flaw him). Then, put the cock into two quarts of sack, and put to it five pounds of raisins of the sun-stoned; some blades of mace, and a few cloves. Put all these into a canvas bag, and a little before you find the ale has been working, put the bag and ale together in vessel. In a week or nine days bottle it up, fill the bottle just above the neck and give it the same time to ripen as other ale." I have no plans to make it. But again, could you buy it online? I would think the raw chicken would cause food poisoning. But maybe not. Also, I should tell you, similar to mead, there is this other recipe called honey wine. You simply mix honey into a light white wine. I made that one once or twice. Also, it is available commercially too. My father once brought it to a family reunion of his brother's in-laws. And he said he was the hit of the party. Also, a word of caution: never add yeast to prune juice. It ferments violently and almost immediately. And when it's done, it tastes like kerosene. I humbly await your replies.
Could the bottle perhaps not been sealed properly? That is actually my main concern, but not sealing properly and it explodes everywhere.
Get some potassium metabisulfite and make a solution to clean all of your gear first. I keep a couple of bottles of the solution handy. The mold was the result of contamination. I've seen it many times making wine. That's the problem with trying to use natural, airborne yeast. It can take several tries to get a good batch and no matter how good you are, that will always be the case. At some point the natural yeast method fails and it's for reasons you can't easily discern. What I don't know is what sort of yeast you need for Mead. Off the top I'd say an ale yeast and not a wine yeast. When I'm trying to rush a batch, I put it on top of the water heater and never let it get above 100F. But this isn't a perfect method and has screwed me a few times. An attic can get up to 140F or worse, which might have killed the yeast that was reacting with your must. When the temperature went down the whole batch probably became a perfect growing medium for bacteria. I'm still only doing gallon batches. My 11/13 batch was just transferred to a distilled water jug (I'm a cheap bastard), they're absolutely clean. Just dump the distilled water (NOT mineral water) and decant from the fermenter.