I came across a reference to CitraSolv concentrate for toner transfer on the inkjet transfer forum. This forum is mostly devoted to arts and crafts relative to image transfers on fabric, paper, etc.
http://groups.yahoo.com/group/inkjet_transfers/ Message #20686.
The technique involves printing your image, placing the image toner side down on the substrate, moistening the back of the image area with the solvent and burnishing to make the transfer. I tried it and it didn't work very well. The image tended to smear. Maybe I was too heavy handed or used too much CitraSolv. It was clear, however, that CitraSolv is an excellent toner solvent (at least for HP toner).
CitraSolv is a trade name and there are lot of different brands. The active ingredient is d-Limonene from citrus rind and it is a very effective degreaser and cleaner. I decided to try it as an adhesion promoter for toner transfer with the normal hot lamination process. I took a piece of regular FR-4 copper clad that had not been cleaned in any way. The board had the usual finger prints and oxidation spots. I wiped it with CitraSolv on a paper towel and let it dry. After the volatiles had evaporated, the board had a very fine oily film. I then taped the circuit image to the board and laminated as usual.
The transfer turned out perfectly; the same as if I had thoroughly cleaned the board with tarnX and acetone. I then erased the circuit toner from the board with the CitraSolv paper towel used to clean it. The interesting thing is that after removing the toner from the board, a very faint image of the circuit could be seen if the board were held obliquely to the light. The areas where the toner was affixed to the copper were faintly lighter than the surrounding copper. This leads me to believe that this stuff is indeed an adhesion promoter for toner.
More work needs to be done to prove that this is a viable process, but you might like to try it. At the very worst, you will have some cleaner for your household chores.
Baxter