uh oh - over-hydrated dough

Add instant yeast.

Add flour as necessary for desired consistency.

To me it sounds like the started had enough abuse to go into sleep mode, the organisms prepared themselves for a long sleep.  Not waking up after 3 feeds would not be unusual but without knowing how you feed your beasties, I'm guessing in the dark.   Many times the acid and hooch they produce to protect themselves is also too acid to wake them up.  A simple doubling of water and food is not enough to dilute the acid so they sleep on or work so minimal, there is no sign of activity. 

Suggestion:  taste the stuff, how sour is it?  (do spit it out)  If not sour, let it stand until it gets there.  Then take a small amount like a level tablespoon or half that (off the bottom) and combine with 4 Tbs of water and enough flour to make a sloppy paste.  Let stand and observe.  If it gets sour... your beasties are waking up, it may take up to 24 hours.  Then you should reduce to a tablespoon and repeat. 

Now if your flour is starting out normal and then turning to a pool of liquid dough and no series of stretch & folds seems to help, that is another problem, a build up of thiol compounds that you can get rid of in about 10 days.  Look under Debra Wink's comment under "Thiol" in the search box. 

Or if you just have a wet dough (and ran out of flour) and want to know the best way to firm it up quickly, try mixing in oat flakes, they work like little sponges and so do dried bread crumbs.

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