> Magnetic sirrer?(posted 9132 days ago)For mixing chemicals. You put the mixing vessel on the thing, drop in the stirring slug and turn it on. Automatic stirring, so you don't have to keep stirring until your arm falls off. Available from Edmund Scientific and I'm sure lots of other places.
> I do have an agitation problem with B&W film. When I shoot portraits > against a gray background, the background has streaks corresponding > to the sprocket holes in the film, no matter how gently I agitate.
And you just told me what the problem is. There's sufficient agitation and there's insufficient agitation, which is what causes streaks, streamers, blotchiness, unevenness etc. There's no such thing as too-violent agitation.
The reason you're getting streaks is that actually there's pretty much no agitation really occuring.
Try this: using a two-reel tank, put a loaded reel on the bottom, an empty reel on top, and use only enough solution to cover the bottom loaded reel. Invert the tank continuously for the first 30 seconds, then two inversions every 30 seconds for the remainder of the development time. Don't even think of being gentle. The result will be smooth, even negs with no streaks etc. Note that you may have to reduce development time because the negs will be getting sufficient agitation.
Vigorous, even constant agitation doesn't cause increased graininess or any other bad things.