urbanfreestyle wrote in post #17960684
Can't say i have had any issues with newton rings, It's very cheap picture frame glass so not sure if it is so think it doesn't make a difference haha!
Newton rings are interference patterns that occur when two shiny surfaces are in close contact, and when the air space between those surfaces varies a bit in size across the surface. They are the bane of printers who use glass negative carriers, and for that reason, enlargers usually use glassless neg carriers. Newton rings are not affected by the thickness of the glass (nor by moisture, even if the effect might look a bit watery).
The Newton ring phenomenon is similar to the effect of colored patterns made by thin oil layers on water.
So basically, by putting a glass sheet on the shiny side of the neg, you are most likely creating Newton rings. Sometimes they are subtle and not easily noticed.
There is special anti-Newton ring glass made. But the best way to avoid them is to go glassless.