i personally do not use balloons. i have bought dolls from people and over the years they go sticky and the colour can seap through the vinyl ruining your doll
. as for nappy bags no no no as they break down over the years too. they are designed too ....for the dump purposes. i use to store clothes in carrier bags in the attic but after a few years they turned to confetti
i make small bags out of cotton material,(natural and breatheable) and sew them and put them in the doll to weight them. i have found this to work well....no leakage or disscolouration. i use small glass beads to weight my head , limbs, and had no problems, and a small cloth bag of large metal ball bearings for extra weight in the head bought from tinkerbells ...brilliant.