Re: Re: Polymer Plate 80% screen Weirdness

When using the talc, put a very small amount on the plate then spread it over the plate with a soft brush. You should be just be barely able to see the talc. The idea is that the talc creates a small clearance between the plate and the neg to allow air to escape.

George
>
> From: Jon Lybrook <jon@terabear.com>
> Date: 2004/02/16 Mon PM 05:09:09 GMT
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: Polymer Plate 80% screen Weirdness
>
> I think this is kind of what I'm seeing, only there are dozens of them,
> and very small, about the diameter of a pin head and larger. I'm getting
> a fair amount of pressure, but maybe the pad needs to be replaced.
>
> Don't I need pure talc, or will perfumed baby powder be okay? I'm a
> little concerned about what affect fragrance and other additives might
> have on the plate and/or film.... Hell, I'm a little concerned what
> affect talc will have inside my frame vacuum!
>
> Jon
>
> On Mon, 16 Feb 2004 Ender100@aol.com wrote:
>
> > I'm not sure what it looks like—dusting talc reminds me of the problem with
> > scanning negatives where talc or mounting fluid is used to avoid Newton's
> > rings. Here is a website showing the effect:
> > http://physics.ucsd.edu/was-sdphul/labs/demos/optics/NEWTRNGS.html
> >
> > It does indeed look very much like a mark made by a water drop....this is
> > probably the culprit.
> >
> > The Newton's Rings effect would also be exacerbated by uneven pressure on the
> > negative/plate contact area—which could be due to eneven pressure of the
> > vacuum table membrane beneath the two.
> >
> > So, get out your old can of baby powder....
> >
> > Hope this helps.
> >
> > Mark Nelson
> >
> >
> > In a message dated 2/16/04 1:59:42 AM, jon@terabear.com writes:
> >
> >
> > > Thanks for your input Mark.  Not sure how the pebbling up against the back
> > > of the plate would do anything to affect the film on top, but who knows? 
> > > I'm wondering if the pebbling on the frame vacuum hasn't somehow affected
> > > the screen in areas where the two came in direct contact with one another.
> > >
> > > I've read on Strange Ross' site he uses a dusting of talc on the plate to
> > > remove air bubbles.  I may try that and/or call Peter at Alpha Graphics
> > > and see what he thinks.  I will let the list know how it goes.
> > >
> > > Thanks!
> > > Jon
> > >
> >
> >
>
>
Received on Tue Feb 17 18:29:03 2004