--- In
Homebrew_PCBs@yahoogroups.com, Kerry Koppert <kkoppert@...> wrote:
>
> On 8/07/2013 2:12 p.m., tda7000 wrote:
> >
> > Washing Soda does work, I have been using it since Day 1 with the
> > photo-resist process as it was the cheapest and easiest for me to get.
> > (And with the blue Chinese resist from eBay, too!)
> >
> > If you have problems with resist staying on between traces, check your
> > mask is dark enough, and you have your printed side right up against
> > the resist etc.
> >
>
> Ah right on. Careful examination of the negative show mottling in the
> black (I'm using artist's tracing paper in a Kyocera FX720 laser but
> I've also tried over-head projector transparency film). The mottling
> corresponds to the unexposed(?) resist left behind. I guess my next
> question is how do you get really black black on transparent film using
> a laser?
You don't use a laser printer!
I get excellent results with an HP 5940 inkjet and Mega Electronics JetStar film.
Leon