We make brisket here pretty regularly - I have couple of questions,
please.

The procedure is simple enough - a large cooking vessel, a 2-3 lb. beef
brisket (currently grass-fed, local, purchased from Whole Foods), and a
couple of jars of store-bought marina sauce. The oven is set at 300 F,
and it cooks for 6-8 hours. The end result is very tasty, very tender,
works great as leftovers on a roll for a kids' sandwich for school, too.

We've tried three different pots - some old, blue thing that I'm
assuming is enameled metal, a cast iron "dutch oven", and now a clay
"dutch oven". The Dutch Oven part isn't completely clear to me, but all
three are big enough pots that have lids that are supposed to be fairly
tight-fitting.

My wife says that she's taken to using a piece of aluminum foil under
the lid and sticking out the sides a bit to form a better seal - when
she didn't do this, she says the whole thing used to dry out too much.

Now, questions:

First, is there any problem or danger with aluminum foil being used this
way, e.g., does it leech anything, do we need to be sure we get a "heavy
duty" kind, etc.? I know I should start by just looking at the
appearance of the aluminum foil when the thing's done cooking, but my
wife seems always to be the person to take it out of the oven - I'll try
to get to doing this today (one is cooking upstairs now).

Second, I have noticed what I'd best describe as a tingly or slightly
numb feeling in my gums after eating this stuff - tasty as it is, it has
me a little concerned, but I'm the only one in the family who has this
reaction. My wife thinks it may just be some herb/spice in the tomato
sauce that I'm sensitive to.

Third, is there a kind of pot that would do this job without the
addition of aluminum foil? I don't know if we'd want an actual airtight
seal as I suspect the lid might still, as we currently have it, pop up
to release pressure, but I don't know since I've never sat and stared at
the thing through the oven door while it's cooking.

Thanks in advance, sorry for the rambling questions.

-S-