As a side note these tubes come in 36" lengths as well and I reckon they could be cut down at the bottom of the tube and epoxied back together for the length someone would need for larger sheet film. I am convinced beyond a doubt after much testing that this gives me the most even, consistent negs I have ever been able to produce(tubes spinning and bobbing in temperature controlled water). Maybe if someone is industrious they could contact the maker and have a run done with black plastic? Would there be enough of a demand?

Mike