Can I tape together fragments of a contrast filter?

Community darkroom has three boxes of Iliford contrast control filters. Every single one of the #2 (normal) filters has been cut up into smaller pieces that will not fill the drawer of a Beseler enlarger. All the others are either trimmed to the right size or even not molested at all. Rrrr.

To get a normal print, one option would be to not use a filter, but that would change the exposure. Not sure by how much, but it's an easy experiment.

The other option would be to tape together some fragments and re-assemble a proper sized filter. The question is, would the Scotch tape mess up the illumination? Also, which side should be taped?

The other-other option would be to buy another set of filters but Rrrr.

Are they to be used above the negative, and how far from the negative is the holder?

Buy a set of filters and take them with you.

Yeah, above the neg in the filter drawer, you will never notice any difference vs. a one-piece original acetate filter! Which side the tape is on also does not make any differential difference in results.

MattKing said:

Are they to be used above the negative, and how far from the negative is the holder?

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It's the standard filter drawer in the Beseler 23c ii enlarger, which is way above the negative, and above the condenser, close to the light bulb. I think maybe the "above the condenser" factor is most important.

wiltw said:

Yeah, above the neg in the filter drawer, you will never notice any difference vs. a one-piece original acetate filter! Which side the tape is on also does not make any differential difference in results.

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I was thinking maybe the actual filtering material was on one or the other side of the plastic.

Pieter12 said:

Buy a set of filters and take them with you.

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I print in a community darkroom & this is what I do...for consistency.

I just ran across this linke Ilford data sheet. It suggests that with the older papers (pre 2020), the 4 and 5 contrast filters need double the exposure of the 00-3 filters, and that with no filter in place you would need to about halve the exposure. That's because the older P paper speeds are 200 for filters 00-3, and 100 for filters 4-5, and 500 for no filter.

But the MULTIGRADE RC DELUXE (new since 2020) that I'm using is 240, 220, and 500 for those same cases. That probably explains why my test run has overexposed 4 and 5 examples.

It also suggests that just leaving out the filter entirely "only" about doubles the exposure. I was thinking it would be a lot more. I will try both the "taping fragments together" experiment and the "just leave out the filter" experiment.

Past experience tells me that if taping the filters works, you will prefer having a "2" filter available.
The speed matching isn't perfect, but it does make contrast changes easier.

The filter should be far out of focus, so the tape probably won't matter. These filters appear to be made of dyed plastic, so the side shouldn't matter either - it's not like a coated glass filter (and some glass filters are also dyed, or a sandwich, so they don't always have the color on the outside).