I just cut a piece of visqueen about 8 inches wide and 8 inches longer than the limb. Get the limb glued up with tape on each side and then wrap the entire limb in the visqueen prior to putting it in the form/ Works great for me and keeps everything really clean/ I also have drilled holes in the form and once the limb is in place I use about 6 12 in. zip ties and zip tie the limb to the form. The zips go around everything but the hose. Layup goes like this. heat strip to the form, formica pressure strip, Limb, pressure strip, heat tape , pressure strip., The add zips , next is air hose and top of form./ Air up to 15 lb or so. let set a bit ,. Cut loose zips and pull them all. The air up in 10 lb progressions to 55/ I also use the fender washers on the sides. six per side and two large ones to catch the overlays and wedge ends holding the riser together . I cook the overlays together with the longbows and one piece curves.
God bless and Merry Christmas to all, Steve