It sounds like either:
1. the film is mislabelled, or
2. the anitihalation layer hasn't dissolved;
3. since 35mm Delta 400 isn't supposed to have an anti-halation backing, maybe it's mislabelled and the anti-halation layer hasn't dissolved.
Try scraping the back of the developed leader (or a frame you don't care about). If you can scrape through to a clear base, then it's definitely a backing. Can you read along the edge to to confirm the film type?
Having it look like a positive doesn't mean it is a positive. A negative with glancing light with a dark background appears as a positive. The density reflects light whereas the clear part absorbs (or allows the light to pass through), so it looks like a positive.
Charlie.
1. the film is mislabelled, or
2. the anitihalation layer hasn't dissolved;
3. since 35mm Delta 400 isn't supposed to have an anti-halation backing, maybe it's mislabelled and the anti-halation layer hasn't dissolved.
Try scraping the back of the developed leader (or a frame you don't care about). If you can scrape through to a clear base, then it's definitely a backing. Can you read along the edge to to confirm the film type?
Having it look like a positive doesn't mean it is a positive. A negative with glancing light with a dark background appears as a positive. The density reflects light whereas the clear part absorbs (or allows the light to pass through), so it looks like a positive.
Charlie.