Hi,
this is the TRF Foil
http://ultrakeet.com.au/graphics/images/gtrf.jpg
Its a pigment based foil that sticks to the toner and provides better etch resistance. just another layer of protection and reduces pitting. i've tried with and without and the foil yields better results.
Explained midway through this article.
http://ultrakeet.com.au/index.php?id...&name=makepcbs
cheers