I'm combining a bunch of leftover starter scraps from last night which were
all pretty active at the time they were used. Some of them were heavy on
the rye side, others heavy on the whole wheat side, and yet others heavy on
the A/P unbleached wheat flour. The combined percentages look approximately
like this: 100% water (though I don't really believe it's that high since
the resulting starter is rather thick, almost like a dough), 75% rye, 12.5%
whole wheat, and 12.5% unbleached A/P wheat flour.

Whatever.

So I used a freshly sanitized one gallon pickle jar, filled it with about a
thousand grams of this stuff, and covered it with plastic film. In about
ten minutes the plastic cover was bulging almost a half inch over the top of
the jar! I don't have a very accurate system like a lab would have, so I
couldn't do scientific measurements, but this foruth generation starter
seems to be very, very busy!

I'm tempted to put a firm seal (screw the lid on with some plastic film
under the lid) over the jar to keep-in some of the gas. Is that a good or
bad idea? Should I just put a little cheesecloth over it instead? I've
been hearing contrary opinions. Why or why wouldn't I seal the jar while
the culture is growing?

Thanks.

Rich Hollenbeck wrote:

Why or why wouldn't I seal the jar while
the culture is growing?

Thanks.

None of my jars seal well enough for an internal pressure of any
significance. You could be in for a bang is yours can, that's one
reason I wouldn't seal it. Cheese cloth lets out the moisture too which
I don't like with a more dry culture, it gets a bit crusty. I use
either film wrap or put the lid on without the rubber seal. Having said
that, my preserving jars vent quite naturally when the pressure gets
too high so if I'm travelling with the jar I do seal it.

TG