RE: BL vs BLB tubes for cyanotype

From: Sandy King ^lt;>
Date: 11/16/05-08:19:14 PM Z
Message-id: <a06020410bfa195cb096f@[]>


The other glass is called Sapphire, not Salarphre, and it is not a
glass that blocks UV. In fact, it allows a very high percentage of
transmission of UV, down to 200 nm. Go to
<> and look
at optmat.htm. From the site, "Sapphire is a synthetic, single
crystal aluminium oxide. Because of its structure, it exhibits large
optical anisotropy and the exact characteristics depend upon the
orientation of the optical axis. Sapphire has five times the strength
of fused silica and superior optical transmission in both the UV and
the IR." Transmission of UV light is 80% at 300 nm, 70% at 250 nm.

I don't have any information about the Salarphire you mention.


>No I am not confused. The papers that I have state quite clearly Starphire,
>PP&G. I also received information about their clear glass and Solarphire
>glass. The Solarphire glass while it might sound interesting, is quite
>opposite from what we like in alt photo, it is a glass that blocks much of
>the UV light. It is true I have not gone back and requested more data from
>PP&G, and the information I got from them was well before the internet made
>communication so fast. I will go check out the site, but I still offer the
>copies of the hard copies in my files from PP&G. Sandy I am not in a
>position to do independent UV transmission readings, but If I stated it back
>in...1999, it came from the pages provided to me from PP&G back in 1992. Is
>it possible that todays' Starphire is not the same as glass made in 1992?
>Quite possibly. Back soon...
>Eric Neilsen Photography
>4101 Commerce Street
>Suite 9
>Dallas, TX 75226
>> -----Original Message-----
>> From: Sandy King []
>> Sent: Wednesday, November 16, 2005 6:22 PM
>> To:
>> 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,,
>>, 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 20:19:31 2005

This archive was generated by hypermail 2.1.8 : 12/01/05-02:04:50 PM Z CST