Re: BL vs BLB tubes for cyanotype

From: ryberg ^lt;[email protected]>
Date: 11/15/05-02:16:57 PM Z
Message-id: <000401c5ea21$8a8ddb20$6500a8c0@computer1>

Loris and Sandy,
     I was more surprised than you at the 3 minute exposure. My first test
strip was 8,9,10,11,12,13 minutes--all overexposed. So I did another at
3,4,5,6,7,8 thinking that perhaps I was mis-reading the 8 minute test.
     My homemade unit is very simple. It has 6 type F15T8 bulbs on 90 mm
centers and places the bulbs about 95 mm above the glass of the contact
frame. The glass is standard hardware store glass sold for window
     The ballasts and first set of bulbs were surplus from American Science
and Surplus, sold as "party lights." I bought 6 of them, took them apart
and glued the sockets on one side of a piece of standard hardware store
shelving material (plastic coated pressed wood fiber.) I screwed the
ballasts on the other side and drilled holes for the wires. I prop the unit
on two matching cardboard boxes. As simple as I could make it.
    I assume the original bulbs were slower than the normal BLB bulbs and
that is why I got such a dramatic difference.
    It sure is nice to have a 3 minute turn around instead of a 15 minute
Charles Portland OR
Received on Tue Nov 15 14:18:08 2005

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