RE: BL vs BLB tubes for cyanotype

Well, not quite 909%. The intended percentage was 90%.

Sandy

> 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 21:15:46 2005