I understand that the best way to make a PCB the photo-resist way is to print a super-dark mask on a transparency put it on a circuit board, expose it and develop. The problem is that is expensive and my printer doesn't print 100% dark.
I currently use vellum (translucent paper) as my paper for PCB masks and even then when I try to do the PCB, some tracks go missing after using the developer yet the rest of the circuit is well intact.
I was researching and noticed from https://smrsoftware.com/vellumtips.php that one could use a spray called "Krylon tm Artist's Matte finish spray #1311" to spray the artwork side of the paper to make the toner appear darker.
I'm wondering, is this a good idea, or are there chemicals in this particular spray that may negatively affect the PCB development process? And if I shouldn't use this spray, then what else can I do to darken the toner on the paper without trying to print on top of the artwork over and over again? Is there a better chemical out there? I'm looking for something that's for sale in canada. Maybe I need a chemical that has a certain ingredient? I don't know.