I tried SFX and developed it in Ilfotec HC 1+31 as recommended in Ilford's data sheet. I set my external meter at ISO 50 and shot through a #29 filter. If you have tried Kodak's High Speed Infrared, SFX may come as a disappointment. The IR effect is not very pronounced. If you want really dramatic results, use real infrared film.(posted 8775 days ago)Anyway, you need not limit your lith printing to infrared negatives. Any negative is fine for lith printing, no matter if it's a contrasty one or a soft one, as lith prints can be controlled to give you any grade between less than 00 and more than 6 or even 7.