Newton Rings and Contact Problems

Contact Issues with polymer photogravure

Newton Rings and Contact problems between the film positive and plate cause these white patches in the print.

Hi Jon,

I’ve been making plates for several years for my photography work and have only recently started having a problem with those dreaded spots on the plate and subsequently the prints.  In researching the problem I came across your web page and it was the ONLY place I have seen a reference to these spots.  I tried you suggestion of drying the transparency and then did a small 4×5 transparency of the image on plate and it seemed okay, but then when I did an 8×10 transparency with the same process, the plate had the dots again.

Do you have any further advice about this problem with Pictorico film?  Or another film that might work without the problem.  It’s maddening and I’ve lost several days of work and lots of plates trying to resolve it with no luck.

I have some Sihl film I’ve never used and considering it.  Anyway, any help you could offer would be very appreciated.  I know Dan Welden and he says it’s a problem with Pictorico.  Is there a work around?

Thanks so much,

Jari Poulin

Hi Jari,

It is much easier to be successful with smaller plates. Larger plates have a learning curve all their own since it is a larger surface area, making tight, contiguous contact with the plate more difficult.

The problem of dark spots (which become white in the print) is typically a contact problem. In some cases it can be attributed to newton rings,. In most cases it is simply a lack of contiguous contact where the film is able to go out of focus and become diffuse in places, weakening the density in the plate in those specific areas.  

Newton rings can occur between the glass of the vacuum frame, and film – or between the film and the plate.  I avoid newton rings on top by using Kreene plastic instead of glass in my vacuum frame.

Two other solutions to avoiding newton rings with larger plates:

1. Pictorico now makes a textured film. The texture creates small cracks where air can escape, avoiding the newton ring issue on some level. 

2. The other solution is to apply baby powder finely to the plate and/or film positive prior to the second exposure to the plate. I use it sparingly, and remove as much as possible with a hake brush before putting in the vacuum frame.  It does the trick.

Hope that helps.  LMK if you have any further questions and best wishes for your project!

Jon Lybrook