> You need to fill the press completely full, so if you have half as
> many grapes as you need for a full pressload, you should inflate the
> balloon to fill up half the space before you start loading the
> press. You do not want empty space at the top, as it will cause the
> balloon to "mushroom out" and break. If you end up with too little
> must to fill the press, you can use pomace from a previous
> pressload.


Ok, thanks David. Since i will have some difficulty to guess the
right amount of crushed grapes to fullfill the bladder i think that
what i should do is to partially inflate the membrane, then fill the
bladder till it's full and discharge some water if i have more grape
to add. Doing this, I will be sure that the bladder is full. After
few try i will be able to better guess the amount of crushed grapes
needed for a full press. What do you think ?

Thanks,
Séb