I had a post about this on the old forum, but I don't think I have time to type out the full answer right now, so I'll give you the short version. (Maybe I should write it up completely again and ask Secrist to post it as an article).
IN toy shops you can buy small double plastic bottles for dolls that look like they are drinking the milk, once turn back upright ,the bottle is full again, same with orange juice.
Heather M, that was me with the toy bottles, but I did what you suggested and did them with the white fabric softner, Everyone at the show asked me what it was , I know it,s bad but somethings you learn you do have to keep under wraps, when it,s your opersition. So I said it was long life, a white lie I know. But if I have anything to share on the forum, I,m only too eager to assist, the same as students of other porcelain doll makers, I,m only eager to provide the information I have learnt over the past 21 yrs, so the craft can carry one and prosper. Thanks for sharing your info.June M from Oz