I have had great success with two options. If the enlarged negative is to be 10" X 12" or less, then I use a direct duplicating orthochromatic film and post-flash it to produce the base mask (I think that is what it is called). If the enlarged negative is to be larger than 10" x 12" then I use direct duplicating mylar or duplicating paper with the same post flash. Works great, and none of the back and forth. Just do it. by the way all of this processes in regular Dektol.