# Starphire grades for UV transparency



## Corpus Callosum (Apr 7, 2007)

I found a local source for starphire glass that's priced good enough. I'm wondering if there are different grades of starphire glass that let different amounts of UV through it. Should I double check something about this glass (short of testing it myself since I lack the UV meter / equipment), or is any starphire glass that I can buy good enough?

Thanks,


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## Dangerously (Dec 19, 2007)

Call this company and check:

http://www.pgo.com/pdf/ppg_starphire.pdf

I don't think there are different grades of it, but I'm not sure.


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## Corpus Callosum (Apr 7, 2007)

Ok, I gave them a call and the northeast sales guy was pretty helpful. He said there's only one grade of commercially made starphire glass so essentially it's the same thing no matter where I get it. But he did mention that there are some other types of glass that would work for my application as well, depending on the wavelength of the UVB.

So does anyone know what nanometer UVB is ?


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## Catfur (Oct 5, 2004)

UVB = 280-315nM

Peak Vitamin D synthesis = 295-297nM

Wikipedia = your friend and mine


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## Dancing frogs (Feb 20, 2004)

I don't have any info you're looking for, but thought I'd chime in, the sample I seen of the stuff is way cool...it was about 3/4" thick, and not a hint of tint....real cool stuff.

Definatly keep us posted what you find out, using starphire glass would be way easier than using acrylic.

(please excuse worthless post...just did it to subscribe :mrgreen: )


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## Corpus Callosum (Apr 7, 2007)

Thanks Clayton, I should have searched more before posting!

Gonna give the guy a call back later this week and see what he suggests for that nanometer range. Still, starphire is probably the easiest for me to get a hold of locally.

Brian, yea I've seen starphire glass before, when looking at it from the sides you should see nothing more than crystal clear and maybe slight bluish tint, nothing like the heavy green tint of the standard glass. And it should last hmm forever(?) compared to the acrylic counterpart.. cool stuff.


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## dneafse (Nov 1, 2006)

Michael,

Have you followed up on researching Starphire glass for its UV-B transparency?

Figure 1c in the paper located here (Krizek, Clark, & Mirecki 2005):

http://www.blackwell-synergy.com/doi/pdf/10.1562/2005-08-09-RA-645

seems to show that transmittance drops off sharply around 300 nm, right in the biologically-useful sweet spot. Perhaps there's still enough transmission to be helpful, though. Has anyone else out there experimented with this material?

-Dan


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## Ed (Sep 19, 2004)

What UVB meter were they using? There can be some significant variation in the type of meter used. 

Ed


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## dneafse (Nov 1, 2006)

Ed,

They say they used a Perkin Elmer UV-VIS scanning spectrometer (model Lambda 10) to measure spectral transmission. The figure shows a distinctly different range of wavelength transmission for low-Fe glass (Starphire) relative to normal high-Fe glass, but it's hard to say how accurate the measurements may be in absolute terms. 

It would be interesting to see a direct comparison of the UV transmittance spectra of Solacryl and Starphire using the same instrument for measurement. My wetlab days are behind me--anyone out there with easy access to a spec? I'll bet we could round up some scraps of Starphire and Solacryl for a proper test.

-Dan


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## Corpus Callosum (Apr 7, 2007)

Sorry for the delay, been busy.

Here is what I found out talking with the company more. Here is a list of all the materials they sell: http://www.pgo.com/link_com_opt/materials.html . The most cost effective ones are the Starphire and Borofloat.

Just to recap we have UVB transmission at the range of 280-315 nanometers and peak Vitamin D synthesis at 295-297 nanometers.

Looking at the starphire spec sheet http://www.pgo.com/pdf/ppg_starphire.pdf which was done using 1/4" glass, there is less than 5 percent transmission at 330 nanometers, meaning at around 300 nanometers or 295-297 nanometers there is likely no UVB transmission at all. There may be a bit more transmission at 1/8" glass instead, but we could not find a spec sheet on it and the representative told me it would not be that much different just a little bit more transmission. According to this information, Starphire glass doesn't seem to transmit UVB at all, which brings me back to the question of different grades of Starphire since there has been mention of Starphire passing UVB just fine (in the research article mentioned above and other sources I have found).

Now, let's move on to Borofloat, http://www.pgo.com/pdf/borofloat.pdf . These numbers were using 1/8" glass, but regardless of that, it seems that Borofloat transmits a great deal more UVB than Starphire. At the 300 nanometer range (which is right near our optimum range of 295-297 nanometers) we have 46 percent transmission. Even in a glass sample of Borofloat that was 1cm thick, I was given the following numbers by the representative: at 280 nanometers transmission is below 5 percent and pretty much begins here, the slope remains straight all the way up to 320 nanometers where it reaches 90 percent transmission, so even in this thicker piece of glass there is around the same transmission at the 300 nanometer range. I am in the process of getting a list of distributors but their price range from the factory was around 17 dollars a square foot with a minimum order of 250 dollars. I got the contact information of a local distributor in my area that I will work with and see if I can buy sheets in bulk from him.

All the information in this post is from the representative and his spec sheets, otherwise I have no other sources to verify this information.


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## Corpus Callosum (Apr 7, 2007)

I've been calling up some distributors to check accessibility of some of these materials. I need to look into the UVB transmission of rolled Pyrex borosilicate as I was given a good price quote on that, but it should be around the same as the Borofloat since they are both borosilicate glasses. I also need to check on transmission of another type of glass called Diamant which I can get locally as well. Vycor is a fused silica glass that I also looked into as it's specifically for UV transmission but the price on it was not suitable for our application.


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