[alt-photo] Cyano experience on Al plates

[Rajul]

When Masa was my print medium, I ran into bleeding problems from  
using 2A:1B. Based on what Chris A. demonstrated a while back, I  
switched to 1A:2B and was thankful that the observation was  
confirmable and bleeding was eliminated.

The experience on Al plates has been illuminating:

1A + 2B prints only 45-100% of the 21-step wedge. Hilites and hi MTs  
remain open for gum to leave its mark. The various cyano densities of  
the printed steps are visible immediately on development with 1  
vinegar:5 H20 and do not increase with time.

Since bleeding problems are less likely to occur with a non-porous  
medium (as with prepared Al plates),  a quick run with 2A + 1B showed:
	- following exposure (1 hour), the usual gray for overexposed areas  
was not visible.
	- on vinegar:water development, the printed cyanos appear as  
undifferentiated mid-tones.
	- after standing for ~2 hours or so, the densest cyanos are a robust  
dark, and are 				differentiated from MT densities. Hilites do not  
print. I will check this out with a step 			wedge when I next run  
cyanos.

Thus, by changing the ratio of A:B, I can modulate the contribution  
of cyano and of gum passes that follow. One more handle to play with.

Rajul