RE: PPG Starphire Glass ( ?? Questioning My Data)

Eric,

Unless you have actually measured the
transmission of a piece of Starphire glass at 5.6
mm thickness there is no way you can be sure what
data is correct, that of PPG or PG&O. My
inclination is to suspect that they are both
right and that the problem is that the data is
being provided in a form that one of us does not
understand.

Both samples I have come from PPG, one sample was
acquired back in 2000 or so, another a couple of
years back. Neither has any yellowish color to it.

Barring further information this is where matters stand for me at this time.

1. There is some conflicting data on UV
transmission of Staphire glass from what would
appear to be reliable sources.

2. Even if Eric's original data is correct and
the Starphire class does in fact transmit a high
percentage of UV radiation below 350 nm, none of
the commonly used light sources are able to make
much use of the increased transmission. For
example, especially SA tubes and the NuArc 26-1k
mercury vapor and metal halide bulbs, which put
out very little or no radiation in the range
below 350 nm. In theory the BL and BLB, which put
out some radiation down to 300 nnm, might be able
to take some advantage of a glass with increased
transmission in the 300 nm to 350 nm range, but
as noted, I did not observe this in my tests.

3. Get beyond the theory and test yourself. I
have tested samples of clear Starphire against
plain white float glass with carbon, kallitype
and palladium printing. I found no measurable
difference in printing speed at the thickness
tested, i.e. 3.3 mm. Printing was done with a
bank of BL tubes and with a NuArc 26-1k with a
metal halide bulb. I do not rule out the
possibility that the use of thicker class might
give different results. In fact, I was surprised
by the results with the thinner glass since even
the PG&O data indicates that Starphire transmits
a slightly higher percentage of radiation than
plain float glass in the range between 350 nm to
450 nm, and I expected at least a slight increase
in printing speed. But I repeated the test
several times with the same result. No measurable
difference in printing speed between Starphire
and plain float glass at similar thickness.

If you dispute my results, do your own tests and
share the results. And be sure to write up
exactly what you did so any of us can do a
verification check on your results. In fact, I
encourage anyone on the list who believes there
is anything to be gained by switching glasses to
make the comparison. But until see the results
of empirical testing that proves Starphire offers
significant practical advantage over plain white
float glass I will personally hold on to my money.

Sandy

>I sent Sandy a tif of the particular data. Not sure what more I can do for
>you Sandy. The Information on the PGO site is accurate except the
>transmission portion. It does however, seem to match SOLARPHIRE composition
>and the transmission data. Solarphire has a transmission of about 5% at 320,
>33.9 at 350nm. Perhaps the people at PGO have their web site information
>wrong. Where did you get your sample? PGO? Or directly from PPG?
>
>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: Thursday, November 17, 2005 11:28 PM
>> To: alt-photo-process-l@sask.usask.ca
>> Subject: Re: PPG Starphire Glass ( ?? Questioning My Data)
>>
>> Since I have not seen the data that was faxed to
>> Eric today by PPG I have no idea how it compares
>> to the data he provided back in 1999. However,
>> there is still a real discrepancy here with the
>> data. Last evening I sent to the list a link to a
>> data sheet from Precision Glass and Optics,
>> www.pgo.com. The specific link was
>> http://www.pgo.com/pdf/ppg_starphire.pdf.
>>
>> Now, here is the thing. PG&O is one of the actual
> > fabricators of PPG Starfire glass. If you go to
>> the link above you will see that the information
>> they provide about this glass is very specific in
>> that it includes things such as available
>> thicknesses, chemical composition, electrical and
>> thermal characteristics, as well as transmission
>> from 330 nm up to 2100 nm. You really get the
>> impression that the folks who prepared this data
>> sheet knew their stuff. And I would think that if
>> anyone would know the real transmission data it
>> would be a fabricator rather than distributor.
>>
>> Now, the plain fact is that the transmission data
>> provided by this fabricator of Starphire, at 5.6
>> mm thickness, is very different from what Eric
>> provided back in 1999, and I presume very
>> different from the data he was faxed today by
>> PPG, since he claims it is very close to his old
>> data.
>>
>> So Eric's information is interesting, but it
>> hardly closes the case on the question of the
>> real UV transmission of Starphire. Course,
>> analysis by spectrophotometer would answer the
>> question and I hope to find someone to do this
>> testing.
>>
>> BTW, if anyone would like to test the Starphire
>> glass against plain white float glass, which I
>> encourage, you can obtain a sample piece of
>> current production Starphire in 4" X 6" size by
>> calling the folks at PPG. I have also heard that
>> some Lowes stores stock Starphire, but have never
>> seen it in my area of the country. Just make sure
>> that the float glass to which you compare it is
>> of modern fabrication and has no coating.
>>
>>
>>
>> Sandy
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> >After last nights back and forth, I was indeed going to call PPG.
>> >
>> >This required all of 3 minutes and a short wait for a return call. I
>> >received a call back from Penny Bridges. She has since faxed to me data
>> for
>> >both the Starphire glass and SOLARPHIRE glass. The thinnest that the
>> >Starphire is listed as being manufactured is 1/8” or 3.3mm and all the
>> way
>> >up to ¾. The data sheets do differ somewhat from those I received in
>> 1992
>> >as one would expect; most businesses update their literature. I received
>> >separate sheets for 4mm and 8mm and this one combines the information and
>> >transmission data in 10nm increments and only shows transmission data for
>> a
>> >glass with a thickness of 5.66mm. It does not show up on the available
>> sizes
>> >but that is what is referred to in the chart.
>> >
>> >While it does not match my data, as one would expect from different
>> >thickness of glass, it does come darn close to the 4mm data that I have.
>> It
>> >is not what I believe to be true as Sandy indicated in his email, but
>> what I
>> >know to be true based on the manufactures data. Penny said that they have
>> >not changed it since they first starting making it but do offer a
>> coating.
>> >
>> >It took very me little effort and would certainly have been something
>> that I
>> >would have done if I were to include test information about a type glass
>> in
>> >a book : ) But wait, that is what I DID back in 1992. It appears in my
>> book
>> >on platinum printing. I don't site all the data. But do talk about why
>> and
>> >when one might benefit from using it.
>> >
>> >
>> >This data also talks about the infrared quality of the glass. I have not
>> >studied gum like I have studied platinum/palladium printing. It may be
>> that
>> >Judy's experience with Starphire has something to do with other
>> >characteristics of the glass that are not beneficial to the chemistry she
>> >used.
>> >
>> >
>> >At this moment, I can't lay my hands on them which does bother me. I
>> took
>> >them out of my notes to make copies for some students and can't locate
>> them.
>> >I do however, have the data for the 4mm which is what Sandy googled.
>> >
>> >I will however, be glad to post PDF's of the documents after I receive
>> them
>> >in the mail. The faxes are OK, but I'd rather wait at least until I have
>> a
>> >chance to print them with my higher quality printer. I am sure she'll fax
>> >them to you too Sandy.
>> >
>> >The PPG web site that I posted last night has their phone number. I
>> suggest
> > >calling them.
>> >
>> >
>> >
>> >
>> >Eric Neilsen Photography
>> >4101 Commerce Street, Suite 9
>> >Dallas, TX 75226
>> >214-827-8301
>> >http://ericneilsenphotography.com
Received on Fri Nov 18 09:18:31 2005