Re: Polymer Plate 80% screen Weirdness

From: Jon Lybrook ^lt;jon@terabear.com>
Date: 02/16/04-11:09:09 AM Z
Message-id: <Pine.LNX.4.44.0402160952330.31281-100000@terabear.com>

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 Mon Feb 16 11:09:22 2004

This archive was generated by hypermail 2.1.8 : 03/02/04-11:35:09 AM Z CST