Hi,
I have converted my filters from 1.25 to 31mm. Is has been done by Optical Structure. One of the filters, SII 3nm, is destroyed. I attach a link to two images that shows the filter itself and a flat that shows that the filter is destroyed.

Link to images

I get following answer from OpticalStructures to the damge :  The bad coating underneath where the filter cell was is to be expected because the filter coating can't be expected to hold up underneath the filter cell. So when the 1.25" filter cell was removed and replaced by a 31mm ring, this bad coating is exposed.

I am not an expert so I ask for opinions to their statement. For me this seems more like an accident when the 31mm was mounted. If true I mean that they should have given  a warning  that the filter could be damaged. I have never heard or seen such a warning, have any of you?
Edited ...
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