From: Sandy King (sanking@clemson.edu)
Date: 11/10/01-08:22:49 PM Z
Judy Seigel wrote:
>Well, Sandy...
>
>
>Tho this gum printer was focussed enough to disprove 50 years of canonic
>myth in her first summer of serious testing -- Of course Anderson,
>Crawford, Scopick & Dudley & Henney et al were ripe for the plucking, but
>it was done with the 21-step, NOT "sensitometry." What was *meaningful*
>was seeing through false assumptions (tho granted that took a while).
I make no distinction between testing log density values with a
densitometer and testing with a 21-step guide. I do both and find
them equally useful.
> but in any event I've always found that the number of
>steps is the safest guide to "speed."
The number of steps visible on a printed step-wedge is not a safe
guide to speed. For example, you may have 18 steps discrete steps
visible, but no maximum density. Lacking information about the first
maximum black, what do you know about speed?
>
>I don't recall that bottom line. Where is it?
I will have to refer you to the archives.
> I would add that I keep all of my solutions topped off, or almost
> > so, in storage.
>
>Hmmmmmm..... I had suggested that the mostly empty bottle could be a
>factor in the deterioration, but you raise a point here -- if you keep
>your solutions "topped off" in storage, then they're not aging, because
>you add fresh.
Good thought, but I test with the stock solutions that I use to
replenish, and these solutions are kept topped off. I top off the
working solution with the stock solution, then add back to the stock
as necessary.
>
>So we have a couple of different questions:
>
>1. How am di in solution would keep in full bottle.
>
>2. If there's a difference in the way it does or doesn't keep in nearly
>empty bottle.
Answer to #1, seems to keep very well. Answer to #2, don't know for
sure since I don't work this way.
>
>And what else could account for difference in our findings. One point
>again may be Dave's suggestion about the difference in MECHANICS of our
>two processes. Another thought is difference in our concentration. As I
>recall you're using a 2% solution -- might as well just say the words
>"ammonium dichromate" in the room.
Concentration of our solutions is in fact very different. My stock
solutions range from 1/4 % to 6%, much less than the 27% you describe.
Sandy
--
This archive was generated by hypermail 2b30 : 12/10/01-11:12:21 AM Z CST