started DIY in February. up until yesterday I always used 15ml glass bottles to make my recipes. I have a str8 snickerdoodle V1 recipe that I like very much. I decided to make up a 50ml batch using a very rubbery bottle. I noticed after just a couple 8 minute cycles with the ultrasonic the color of the liquid changed much faster than it does using a glass bottle. So I came to the assumption using a rubbery bottle steeps a liquid faster than a glass bottle. Anyone care to comment? All comments are welcome.