Newton rings on filters

Hello,

I like to hear about experiences using of a filter (a ND 2x).
The filter possess one Newton rings at centre of the filter, and some
vacuum or layer of air inside it.
Holding some hours in Sun rays does not help.Too short?

My question:
-do it influences any sharpness of pictures?
-how to remove this from filter
Best
Gerard

Gerard
If you had a good filter this phenomenon would never happen. Good filters are colored in the mass of the glass. These problems do only occur in "sandwich filters". two glasses and a gelatine sheet inside.
Normally those ND filters are coloured in the mass. Very probably you have a polarizing filter which are generally constructed in the "sandwich technology" Hetaparite crystals are melted in the gelatine and iserted between the glasses. When old those crystals modify their estructure and dimensions, loose their properties and cause internal strains that you see like Newton's rings.
LP