Apropos of this thread, I've been printing alt-process recently with a 13 W spiral BLB in a reflector clamp-on lamp. I've been using my Graylab 300 timer; I set it to focus, turn it on, and switch to "time" when the flickering stops. For multi-minute exposures, this ought to be more than accurate enough, and it makes me feel good.

FWIW, I've been getting good salt print exposure (now that I finally found a paper that doesn't fog before the silver nitrate dries) with around ten minutes, lamp about eight inches above the printing frame. Same lamp requires a similar time for cyanotype rex (ferric ammonium citrate sensitized) and VDB rex (ferric ammonium citrate sensitized, developed with 12.5% silver nitrate). And I don't have to fight with variations in sun exposure, try to find a place that isn't shaded by the trees, heck, I can even print at night if that's when it's convenient...

And the Strathmore Bristol is the *best* paper I've tried so far (though on a budget, I haven't wanted to order $50 worth of some specialty paper in order to find out if it'll work) for silver processes -- almost no fog, and it takes up enough chemical (at least on salt prints) to print with good density. Now I just need to figure how to keep it from fading in the pre-fix wash and fixer; goes from a near-neutral black to rusty-looking brown -- but I'll post elsewhere on that if I don't find the answer pretty quickly.