RE: BL vs BLB tubes for cyanotype

Sandy, I think you will find this most informative.

http://www.ppg.com/gls_commercial/documents/PPG%20Glass%20Product%20Data%20-
%20monolithic.pdf

Eric Neilsen Photography
4101 Commerce Street
Suite 9
Dallas, TX 75226
http://e.neilsen.home.att.net
http://ericneilsenphotography.com
 

> -----Original Message-----
> From: Sandy King [mailto:sanking@clemson.edu]
> Sent: Wednesday, November 16, 2005 6:22 PM
> To: alt-photo-process-l@sask.usask.ca
> Subject: RE: BL vs BLB tubes for cyanotype
>
> Eric,
>
> I am puzzled by some statement you have made about Starphire. In your
> messages of today you have suggested that Starphire glass transmits a
> significant percentage of radiation below 350 nm. And you have been
> saying this for a very long time. For example, in a message to the
> alt-photo-list back in December of 1999 you wrote, and I cite the
> message:
>
> On Sat, 4 Dec 1999, Eric Neilsen wrote:
>
> OK , I found my charts. Starphire transmits 35.5 % of UV light @
> 300nm where Standard transmits .3%; @310nm 53.1% Star and .8%
> Standard; @320nm 67.9% Star and 9.1% Standard,; @330nm 79.2% Star and
> 34.4% Standard; @340 86.1% Star and 61% Standard; @350nm 89.1% and
> 77% . At 360nm and above it stays at about 91% for Starphire and 86%
> for
> Standard.
>
> Contrast your information with the specifications in this link,,
> http://www.pgo.com/pdf/ppg_starphire.pdf, which gives the following
> figures. Unless I am missing something terribly obvious, your figures
> are very different from those at this source, which are:
>
> Starphire Glass
>
> Transmisson: (@ 5.6mm thick)
>
> @330 nm < 5%
>
> @350 50%
>
> @380-680 nm 90%+
>
> I am wondering if somewhere in your research you did not confuse
> Starphire glass with Sapphire glass? In fact, the figures you cited
> in the 1999 message for Starphire are much closer to current
> transmission figures I was able to get today on the web for Sapphire
> glass.
>
> Sandy
Received on Wed Nov 16 20:22:01 2005