Let me also suggest another article on the unblinkingeye.com site on making enlarged negatives by reversal processing, at http://unblinkingeye.com/Articles/NbyR/nbyr.html
Originally Posted by doughowk
Ed Buffaloe's procedure follow rather closely an ingenious method develped by Liam Lawless and published in Post Factory Photograpy some years ago. I used Liam's method for several years and can state for a fact that this method works quite well.
There is somewhat less control with the reversal process than with the positive/negative method but there are also some advantages.
From purely economic point of view this method of making enlarged negatives for alternative printing is clearly less expensive than making digital negatives