[Leica] Re: Solutions for avoiding newton rings

["Michael D. Turner" <mike@lcl-imaging.com>]

Jim Brick wrote:

> Newton rings are caused by imperfect contact by part of the film with
> glass. Film with more curl are more prone to newton rings. Current humidity
> also is a factor as to the severity of the problem.
>
> One solution is, of course, to eliminate all contact between film and
> glass. This is why glassless neg carriers are so popular.
>

Sigh, this is always a mixed bag. If you need the original to be flat (high
magnification) or in contact with masks, i.e. contrast masks, then Newton is
your not-so-friendly cohort.

>
> Many years ago (1950's) Kodak recommended rubbing the glass (that which has
> contact with the film) with fine (00) pumice powder using cotton. This
> basically makes the surface layer of the glass, less "glazed" so that the
> type of film/glass contact, producing newton rings, does not take place.
> The use of 00 pumice powder makes no humanly observable difference. But it
> makes a difference in how the film base and glass get along.
>

There are "anti-newton" sprays on the market. They sometimes work, but
"gunk"-up your original and sometimes also trap dust (but so do glass
carriers). What I usually found to be more successful was to put some
cornstarch in a spray bottle ,"poof" it into the air, drag the original
through it. This amounts to putting very small dust particles between the film
and the glass. It usually works and doesn't leave a residue on your original
which needs to be cleaned off.

I've never tried the pumice trick above, but it has to be better than
anti-newton glass which imposes an obnoxious pattern on your print  at
moderate to high magnification, particularly in large continuous areas, such
as sky.

You just have to try what works, in your particular circumstance. Yes, high
humidity promotes rings, low humidity promotes dust. Dust helps reduce
rings....

Ain't it fun?

- -Mike