Here is a picture for my QU students who need a visual about how to 'tent" the fabric while it cures. The batik underneath the plastic has had the dyes painted on so the dyed areas are not as saturated as they would be if submerged in a dye bath so they could dry out too fast and give lighter results than I want for this piece. The batik is on stretcher bars so air can circulate underneath which could hasten the drying process as well. Since my studio is quite cool at the moment I'm not too worried that they will dry out too soon but propping the plastic up and over the piece will give the dyes a bit more time to cure. You can see that there are tall paint jars that hold the plastic up and off the fabric. Very high tech.
One other idea if you are living in a VERY arid environment is to put plastic underneath the piece with a pad of wet newspapers on top of that. Then the strethced fabric on the frame goes over all that. Top it off with the tent of plastic.This will give the batik or silk or whatever you are dyeing on the frame extra humidity to keep it nice and damp under there for a longer period of time.