RE: BL vs BLB tubes for cyanotype

Eric,

Not only that, but who knows the characteristics in terms of UV
transmission of the plain float glass you and I used in comparing
whatever it was we compared the float glass to. Fact is, lots of what
we believe to be plain white float glass blocks a high percentage of
UV radiation, while others types pass up to 909%.

Sandy

>
>PG&O may have a glass that they call Starphire, but it appears that that is
>a product line rather than a single type of glass. Next thing you know,
>there will be three type of paper called Platine : )
>
>Cheers
>EJ Neilsen
>
>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 20:57:14 2005