Homebrew PCBs

Well I don't know, I'm using chemicals for serigraphy "for
professional use only", more precisely, bichromate-sensitivized vinyl
dispersion, used for TEXTILE printing. that is, for making originals
to print t-shirts. this emulsion it's for water-based inks.

The sodium hydroxide will remove all of the emulsion, while what I
want to remove is a little "veil" that stays there after rinsing.

--- In Homebrew_PCBs@yahoogroups.com, "derekhawkins"
<derekhawkins@y...> wrote:
> Clarification....
> 
> >sorry, I didn't express myself clearly. the residue is there after
> >developing but before going into ferric chloride.
> 
> The conventional process uses sodium hydroxide or something similar 
> here. You apparently have to resort to steel wool...Not good.
> 
> >to finally remove the emulsion, i do use screen cleaner. but it seems
> >to attack copper. i was told to use bleach or sodium hydroxide which
> >can remove the emulsion and won't attack copper... but I'm not so sure
> >about that. I use paint thinner and a little more work, and it goes
> >away, and thinner surely doesn't attack copper.
> 
> The conventional process normally uses acetone here. You apparently use 
> what you can get. I suspect recommendations to use bleach or sodium 
> hydroxide were aimed at the previous step above where "unfriendly to 
> copper" doesn't matter since ferric chloride would be the next step.