RE: BL vs BLB tubes for cyanotype

Sandy, I will look again, but I seem to remember that no other wave length
being mentioned other than 400nm. Why was the test information not included?
Does you information match that provided by PP&G? If not, Why not? What
mixture of PT and PD did you test? Did you test just PT?

While Super Actinic bulbs are popular among Palladium printers, BL bulbs are
quite popular among many alternative printers. They have a substantial
amount of their output at or below 360 nm and that is where Starphire glass
will show the increase in speed. It is also true that PT is much faster at
lower humidities, and if one is using PT and not making Ziahypes, you would
expect to find and increase in the contrast of your print.

With the move away from BL by some platinum printers to super actinic, the
number of printers seeing this would decrease. There would also be very
little reason to use Starphire glass if you use much more palladium, well
over 50%, because palladium does not see the light as well as platinum at
the lower wave lengths. How do I know? I ran the test back in the early
90's when I received the reports at the Platinum Gallery in Santa Fe as well
as seeing the data included in Mike Ware's paper, An Investigation of
Platinum Printing.

Where did you see an advertisement for Starphire glass making a claim of 3 -
6 % more than regular glass in the range of 400 to 500 nm? When I look at
the spectral data sheet for Starphire glass, it is apparent that the real
benefit would be for light sources and processes which see and use light
that is in the 300 to 360nm range. I don't believe that I have ever seen
anybody make a claim about Starphire glass being an effective remedy to
slower speeds or lack of contrast with regards to light in the 400nm to
500nm range. I believe it would be more accurate to discuss the glass in its
most appropriate use, that in the range of 300 to 400nm or that of a typical
BL bulb.

In looking further at the chapter on light output, I see very little
difference in the BL and BLB light output you have included in the chapter.
These two don't match the data that I have seen from both GE and Phillips.
BLB bulbs have a very sharp output at 360, exceeding that of BL bulbs, but
you show both to be the same? Something is a mis.

I would be happy to send you the spectral data provided to me by PP&G back
in 1992 or so or that from GE.

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 8:44 AM
> To: alt-photo-process-l@sask.usask.ca
> Subject: RE: BL vs BLB tubes for cyanotype
>
> Eric,
>
> Your statement that the Appendix in Dick Arentz' book on speciality
> glass concluded that there was no advantage to Starphire glass does
> not accurately represent what is stated. And I am very familiar with
> the Appendix since I wrote it. Here is what I did and wrote.
>
> 1. I compared the transmission of plain float glass with that of
> Starphire glass (both in 1/16" thickness), using a UV transmission
> densitometer with peak at 373 nm and bandwith of 60 nm. The Starphire
> had slightly better transmission, but based on analysis of the data
> the increase in speed would have only amounted to about log 0.5, or
> 1/3 of a stop in glass 3/16" or 1/4" thick.
>
> 2. I tested several processes for speed, using a Stouffer test
> tablet, comparing results in a contact printing frame using 1/16"
> thick plain float glass and 1/16" Starphire glass. And I specifically
> tested several different mixes of palladium and platinum. After
> looking at the results I found there was no advantage at all to
> printing with the Starphire glass, but allowed that use of thicker
> glass in the contact printing frame might give different results,
> perhaps up to 1/3 of a stop faster.
>
> 3. I concluded with the comment "it is almost certain that one could
> reduce printing times slightly by replacing the ordinary plate glass
> in our vacuum frames or contact printing frames with speciality
> glasses that allow the transmittance of a higher percentage of UV
> radiation," but that in my own cases I had considered this carefully
> and "determined that it is not worth the trouble."
>
> I conclude from your comments that you believe one of the advantages
> of Starphire glass is that it allows "more lower end light to pass,
> such as 320 nm to 360 nm." However, many Pt./Pd. printers are using
> light sources which are totally absent of radiation in this range.
> For example, if you look at a SPD chart (spectral power distribution)
> of the Philips Super Actinic tube, which is very popular among
> Pt./Pd. printers, you will see that there is virtually no radiation
> below 360 nm, and none at all below 350 nm. So if anyone finds a
> significant increase in printing speed with the Starphire glass using
> the SA tubes it must be due to greater transmission in the upper UV
> range, not in the lower end.
>
> Sandy
>
>
>
> >But the light out put of the two type is not same. I recently acquired
> Dick
> >Arentz' book on platinum printing to have as a reference when students
> show
> >talking about it, as well as to read Mark Nelson's bit on digital negs.
> The
> >very first page I opened just happened to be about specialty glass; UV
> type.
> >He went on to talk about Starphire (misspelled Starfire) and concluded it
> >had no advantage, based primarily on wave lengths above 400 nm. It has
> very
> >little if any advantage at those wave lengths, which a simple review of
> the
> >transmission data would tell you. Certain glass like Starphire, allow
> much
> >more lower end light to pass, such as 320 nm to 360 nm. If the material
> you
> >are using is sensitive to those wave lengths such as platinum vs
> palladium,
> >then adding light in those wave lengths will speed up your process.
> >
> >
> >I don't think that that much change would be anticipated. BLB typically
> >output mostly between 350 and 370 with the peak at 360. While the BL has
> a
> >much broader output, but also peaks at 360. Your glass would need to be
> >blocking light right at or near 360 to see such a dramatic change.
> >
> >Was your stack of paper constant? And as Sandy pointed out light output
> will
> >fall off after a warm in period.
> >
> >
> >Eric Neilsen Photography
> >4101 Commerce Street
> >Suite 9
> >Dallas, TX 75226
> >http://e.neilsen.home.att.net
> >http://ericneilsenphotography.com
> >
> >> -----Original Message-----
> >> From: ryberg [mailto:cryberg@comcast.net]
> >> Sent: Tuesday, November 15, 2005 5:10 PM
> >> To: alt-photo-process-l@sask.usask.ca
> >> Subject: Re: BL vs BLB tubes for cyanotype
> >>
> >> Michael,
> >> Well, I suppose my glass could be extra transparent to UV, but it
> is
> >> the same glass that I used with the BLB tubes which took 15 minutes.
> > > Charles Portland OR
Received on Wed Nov 16 09:37:30 2005