Someone email me this question today:
"When you're working at home...do you use plastic bags? I couldn't decide whether it was right...it keeps in the water, but would restrict the air."
I am home all day so I can keep the rust dyed pieces hydrated when necessary. I love checking on them, it gets me out of my cold, damp basement studio into the beautiful summer day, which is one of the main reasons I took up rust dyeing.
Using plastic bags just sends more things to the landfill so I try not to use them. Wrapping your rust dyed piece tightly with plastic will restrict the oxygen available. I had an interesting talk with a chemist at Midwest Fiber and Folk Art Show. He said iron oxide formed with less air is black, iron oxide formed with a lot of air is reddish. This might open up a whole world of experimentation for someone.
Would that be you?