RE: BL vs BLB tubes for cyanotype

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 01:10:51 2005