I used Positiv20 spray on a well cleaned PC board. The method of applying a layer of this stuff is described on
here
The medium I used for printing the Circuit design on was a clear PVC type sheet, (used in overhead projectors at schools etc.) The stuff here in South Africa have different names than abroad, so I won’t even be able to begin and tell you what to use. The sheet had one side very smooth, but the other side's surface was course (something like the MATT finish of a photograph, if you know what I mean?)
I always printed on this course side. The tones seemed to melt itself into the sheet, opposed to the smooth side where it seemed to smear. Development was done using UV tubes. Exposed the circuit for about 90 seconds. The development of the board was always my biggest problem. You have to use a solution of Caustic Soda (NaOH) dissolved in water. If the solution was too strong, you destroyed the “negative” in seconds. Too weak, and it took ages, and nothing happened.
Once developed, I etched (and still use this method) the board with equal parts of H20 (Water) H2O2 (40% vol. peroxide) and HCL (Normal swimming pool acid). This takes about a minute vs. 20-30mins with FeCL. (Yes, I do obey the environmental rules etc.)
But, since I learned the transfer method with the Iron, it’s all I use. I now develop far better looking boards than I ever could with the photo-resist method.
My two cents worth.