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Subject: Re: [Homebrew_PCBs] Re: Printers not making pattern opaque enough for UV process

From: DJ Delorie <dj@...>
Date: 2012-02-23

"tda7000" <Tda7000@...> writes:
> I didn't mention it before but I did a rudimentary test by covering
> the board with a credit card and exposing a little bit every minute
> for 7 minutes

FYI using a transmission step wedge is doing the same thing as this,
except it's calibrated. Since the films tell you the step number
target, it means you can get it "dead on" in one test exposure.