Allow the fabric to cool, then unwrap, remove dye stuff and leave to dry. The onion skins worked really well using this method, I did have two other attempts with hot bundling, using ivy leaves and rose leaves. The ivy leaves only left a few yellow splotches. The rose leaves were a little bit more interesting and produced a few shades, and there were a few fairly well defined leaf prints, but overall it looked messy. Part of the issue might be the loose weave of the muslin, it might also work better if the fabric has been treated with a mordant.