I ordered a custom 4x5.65" cut of their current hot mirror which cuts IR to around 925nm. The RED One is sensitive to around 1200nm so there is some room for an improved dichroic formulation.
Rosco's common dichro glass is borasilicate (like picture glass) and chips a bit too easily in the matte box filter holder so something harder is needed.
I spent Friday morning with Henry Cowen at the Round Rock, Texas plant that produces all of Rosco's dichroic glass (as well as steel and glass gobo patterns) and we discussed the development of IR filters with one or more of the following characteristics:
Development priority list
1.Block IR to 1200nm
2.3.3mm thickness
3.Harder Glass than Borosilicate glass
4.Dressing of edges and corners or develop a ‘bezel’ to finish the edges of the glass
5.Labeling of filter (possible laser etch of bezel)
6.Flat and Parallel surface treatment
I'll be having a discussion with Joel Svendsen early next week about what market exists for Rosco in the optical glass world. My first impression is that there is no reason to compete directly with Tiffen and Schneider if they are prepared to bring IR solutions to market. There may be, however, an opportunity to bring a lower-priced filter to market that includes some, but not all, of the above features.
As I noted in my visual observation of the borasilicate glass I used this week, there was no reflection perturbation of fluorescent light when observed at twenty feet from the glass. (Of course, this is hardly scientific) When I consider the horrors imposed on the image by lens optics, I feel the over engineering of Schneider filters to be largely unnecessary (even though I have them in my matte box right now.) Would a lesser piece of glass be flat enough for most shooters?
Michael
Bring rubber gloves. 
Yes, and it doesn't flicker -- it bands. You get scrolling bands of orange in your image if you're using a magnetic-ballast HMI or fluorescent; the brightness/darkness of the bands depends on the shutter speed, and the higher the shutter speed the more noticeable the bands are. You have to stick with a shutter speed that's a multiple of 120 (1/120, 1/60, 1/40, 1/30 etc) to avoid it. Or, go with a high-frequency electronic ballast; those avoid banding (although there can come in some flickering at 1/1000 or 1/2000).
