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This may be a silly question, but what does 'cover' mean in beer recipies?

http://www.rivercottage.net/SeasonalRecipes~April/83/Nettlebeer.aspx

I've made wine before (I have 3 demi-johns waiting to be syphoned, an apple, a pear and a rosehip) so I'm familiar with demi-johns and fermentation locks.

However, I've been looking up various recipies for dandelion and nettle beers and I've managed to get myself confused.

All of the recipies have the same basic steps, warming the various ingredients in a pan of water, etc.

However, some then say to put into a bucket, allow to cool to blood temperature, add yeast etc. then 'cover'.

Does that mean:

1.  Cover (& seal) with a lid (I think not, as it would pop off when it ferments)
2.  Cover with a lid with a fermentation lock in
3.  Cover with a sterilised muslin cloth

Other recipies say to put it into a demi-john, which would obviously need to have a fermentation lock fitted.

They then say after fermentation (4 days or so) rack off into bottles (prefferably with wire seals, given the probable expansion) then leave to age for a wee bit before opening carefully and drinking.

That's enough waffling. 

So, what does 'cover' mean for the fermentation?  Does it need a fermentation lock, or can it be covered with a cloth?

cover with a cloth, it's primarily to keep moulds, dust and the dreaded fruit flies out!!

Great, thanks