To ferment them, I prefere to have them in jars rather then a large container. The reason is to me they get too soft if there's too many of them in a container to ferment. A large container probably be good if your doing thousands of pounds and you own your own grove. Least in my opinion. I liken it to a japanese story about making sushi rice. You must never leave a single grain of rice alone. If left alone it will miss it's friends, it will become unhappy and die, and this will make the rest of the rice sad, and it will die. If you put too few olives together in a batch, they will become sad and die they miss the company. If you put too many olives in a container, like many people they will become angry and unhappy, and they will not be as nice as a perfect batch of cured olives.
The reason I don't use preservatives in any of the cures in my article is, their not needed. Almost all cures for olives have salt. This is why when you pop open a can of commercial black pearl olives you drink the juice it's rather salty. Salt replaces those industrial preservatives. It's cheaper, it's more readily obtained. If someone wanted to get into curing of olives, then it be the best route and cheaper then going out and buying all this industrial stuff. In my opinion it also preserves the old ways, the roots of the experiance. It's why I mentioned Passum and ash.
A problem I had when I first began was the fermented olives also blew the lid off my containers. So I did step up to a fermenter for beer and wine with a airlock on top of it to aid in the release of gas to prevent being woken up in the middle of the night.
Once I got them into jars, I loosely cover with a lid. For my olives when working with lye, I will always use that large stock pot. It's in my opinion safer. Your not moving around 5-6 containers of lye solution, your not leaving it outside for things to get into. Your working with one container, wich is easier to keep track of. Fewer mistakes expecially if your just starting out. Then I pour off the lye, then I change the water periodically to get rid of the lye in the olives. 3-4 times in 50 hours the water needs to be changed. After a brine is made up with lactic acid, and they go into the canning jars and then they go into the fridge, only after when they have finished fermenting do they get a topping of olive oil. I also don't use just straight olive oil, I tend to infuse the olive oil. Usually with garlic, so when you take out your fermented olives, you'll also get a nice hint of garlic and yummy olive oil ontop of the taste of the olive.
I understand your reasoning, so the best advice for anyone to take up this craft is to use a container that suits your needs. I process roughly 800-1500 pounds of olives a year, thanks to my aunts, uncles and grandfather who are always sending me their harvest to cure for them. Large containers do play a role for me, but I don't rely on them as a fermenter. Fermenting them in jars in the fridge is great for me. Little more work, but it's wonderful. I will make note that I don't have a regular home fridge. I got a fridge devoted to just olives. I got it out of the trash, it worked, I cleaned it up and I went to my local brew shop and picked up a temprature regulator used in brewing and set that up to be my "olive cure cave in Italy".
Another thing I do, is never cure with lye alone. Even though I been curing olives for the past 5 years, I've had accidents my self. Mostly lye solution spilt on the ground leading to red skin, peeling, and a few chemical burns, when my brother snuck up behind me with an air horn while I was holding a container of lye. Not only did I get hurt, but he got hurt too. So pair up when working with lye. Since I've paired up and got my girlfriend doing it with me, it's much easier, and I've not had a single accident yet.
Anyone who's getting into it, I'd also encourage them to make their own olive oil. It is so much different from store bought, you'll grow your own trees just to make olive oil once you taste and see the difference.
