Hi, it was a good idea to use bat wash rather than thin fire, as we are tought that the thinfire will disintegrate before the glass slumps properly, particularly if it is bottle glass. however, residue will be left on the glass if you over batwash, are you using bullseye primer?
for your next fireing clean the shelf completely with scrubbing brush and water, do not do it dry as batwash has nasty chemicals in, and leave the shelf to airdry over night, then reapply your batwash, if using bullseye primer, make sure your mix is thin, it should almost be like water and with a very wide soft brush use long even strokes first horizontally, then virtically, then each diaginal allowing each direction to dry before starting the next layer. then stop. you could add one more layer, but the more you add the more dry powder will be loose. the only way you will get the residue off your glass in myu experience is sandblasting or attck with diamond pad. and next time i would recommend taking it to a lower temp and holding for longer, you should get a better slump this way, and if your unsure you can always open your kiln with goggles n gloves on at top temp and see whats happening and adjust schedule to suit, this might be best with bottle glass.
sorry to ramble, hope this makes sense and helps