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Is Plexi replacing glass

Robert;

Transparent aluminum was used by Montgomery Scott (Scotty) in one of the Star Trek movies. (IV IIRC)

Sorry. I just wanted to inject a bit of levity here. Apologies to all. It does beat talking to myself in the darkroom.

PE
 
Just to put the popularity of ST in a proper perspective for those unbelievers out there, just before his death, DeForest Kelley (Dr. McCoy) was a guest of honor at an AMA convention for his publicizing the role of doctors on TV. He got a standing ovation and Dr. Ruth, another guest was upset over the reception given to this upstart new doctor who she had never heard of. She apparently did not get a standing ovation.

Sorry again.

PE
 

Not sure if you got my reference - in the movie when bargaining with the plant manager, Scotty tries to enter the chemical formula for transparent aluminum via talking to the mouse.....

I thought your comment was quite funny
 
I never thought of that, why if 2 inches thick would stand up to ?? gallons of sea water, I suppose that that the glazing over my photographs could be just a few mils !!!!

Won't need the huey.
 
KenM said:
Not sure if you got my reference - in the movie when bargaining with the plant manager, Scotty tries to enter the chemical formula for transparent aluminum via talking to the mouse.....

I thought your comment was quite funny
Click to expand...

I did get it, and that is why I remembered Bones. He handed the mouse to Scotty.

PE
 
Acrylic info

Acrylic is optically superior to glass and safer. Museums prefer acrylic because glass when broken, can slice rare artwork. The primary drawback is of course lack of scratch resistance. I have details about acrylic and glass on our website. If you use acrylic a lot you will really want to check out the trick for paper removal. If you dont already know it, it will make your picture framing life much better.

Glass vs Acrlic (Plexiglas)
Info about standard, UV and non-glare acrylic
Acrylic Cleaning and Static Removal
Trick for Acrylic Paper Mask Removal

Cheers,
Mark
 
Mark, if the "Trick for Acrylic Paper Mask Removal" works I may have to hug you!

Murray
 
fdi said:
If you use acrylic a lot you will really want to check out the trick for paper removal. If you dont already know it, it will make your picture framing life much better.
Click to expand...

Hmm... Lucite comes with a plastic backing these days, which is really "static-y." I'm going to try this technique with the plastic backing, hope it works!
 
r-brian said:
I've heard that Plexi absorbs more UV rays than glass so actually protects the print better than glass.
Click to expand...

Plexiglas, Acrylics and most other plastics are by themselves very poor UV filters. Ordinary glasses filter out a LOT of UV - that is why it is nearly impossible to get a tan through the average window.
Coatings are necessary on plastics (see sunglasses) to attenuate UV.

The Frame Destination web site referenced by "fdi" has a lot of GOOD information.
 

Ed,

It is possible to incorporate UV filters into acrylics, they do not have to be coatings. This is one of the advantages of acrylic over glass. See the Tru Vue table on page 2 of this pdf for some values for UV blocking: according to their figures their uncoated glass blocks 45%, their plain acrylic blocks 66%. OP-3 acrylic (OP-3 is not a coating) blocks >98% UV. They do not list the numbers for transparent aluminium - these are probably only released on a need-to-know basis.

Here is Cyro's data sheet on OP-3. This has spectral absorption curves for float glass, plain acrylic and OP-3 treated acrylic.

Best,
Helen
 
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Helen B said:
Ed,

It is possible to incorporate UV filters into acrylics, they do not have to be coatings. This is one of the advantages of acrylic over glass.
Click to expand...

If one saunters down to the local home Depot and purchases a sheet of plexiglas, VERY little UV will be absorbed by that material. It is possible to incorporate into, as well as coat on, UV - inhibitors, but I my frame of thought, neither are "ordinary" materials. Possibly there is a bit of "semantics dancing" here between "our" and "ordinary".

As far as "float glass" absorbtion - I don't know. I've done Spectral Transmission analyses on a variety of materials (transparent aluminum - NO) and I disagree. I can only wonder about their testing parameters - ~ 68% would be possible, I guess, through a very thin sheet of float glass (do they mean ordinary window glass?).

Case in point: The Hasselblad lens designed for UV work. This puppy does not use glass at all ... the elements are constructed of calcite- flourspar - (I do not have the Data Sheet in hand - so don't break my a.. uh - fingers here), to minimize UV attenuation.

Also, see John M. Ott's Health and Light ISBN: 0-671-47433-2; where he speaks of the failure of time-lapse photography in recording the progression of pumpkin seeds to mature fruit due to the "ordinary glass" enclosures constructed to shield them from movement (Disney Studios assignment for "Cinderella"). Pumpkins need UV to mature - so plexiglas had to be - and was - subtituted for glass - and the problem was solved.
 
If the Acrylics are poor UV filters would they be optimum for print frames used in UV light boxes for Platinum print exposure etc?
 
From a Wikipedia article:

"...Transparent aluminum in the real world:

These are presently produced through the chemical bonding of aluminium with appropriate elements in transparent alumina and in ruby, corundum, sapphire, and related aluminium compounds. Traditional photonic bandgaps, based on introducing spatial holes in aluminium, are likewise possible, but these would require the introduction of numerous physical holes with roughly the diameter of the wavelengths of light for which transparency were desired; but such would presumably weaken aluminium structures.

Transparent alumina
Main article: transparent alumina
Aluminium oxide, a chemical compound of aluminium and oxygen (Al2O3) is made transparent through a process of fusing fine particles.

Nanophase aluminium:
Real transparent aluminium can and has been made by using nanophase aluminium. This is aluminium composed of nanometre scale particles as a solid transparent material, whose color can be varied by sizing the particles differently. The particles themselves are smaller than the wavelengths of visible light. Nanophase materials are usually transparent and very hard, with color depending on the size of the particles.

Aluminium oxynitride (AlON):
Aluminium oxynitride (Al23O27N5) marketed under the name ALON is an aluminium composite, having the optical transparency properties of glass, yet four times the strength and hardness.
 
Ed,

The apparent discrepancy in the UV properties of normal soda lime glass is probably in the cut-off wavelength. The degree of attenuation is indeed high, but it doesn't occur at 400 nm - most 'plain glass' (soda lime) transmits quite well until 350 nm to 320 nm, as shown in the Cyro curves and many glass manufacturers' data. The Tru Vue table of UV blocking values states that they are giving values for 300 to 380 nm. If the average were to be taken over an interval starting at a shorter wavelength, the number used to quantify the UV blocking of their plain glass would be greater.

For plastics as well as glass it is best to refer to data on specific materials rather than general types, which is why I referred to Tru Vue and Cyro for data on commonly used glazing materials (eg Acrylite and Acrylite OP-3). Similarly, if selecting a material for a UV print frame it would be better to refer to material-specific data rather than generic data. This is especially true when naming is used so casually - such as the use of 'plexiglass' for a variety of materials other than those sold as Plexiglas (which is not one single material), a trade mark registered by Rohm and Haas in 1936.

The UV transmittance of various types of genuine Plexiglas®.

Best,
Helen
 
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Helen;

You are absolutely correct. In fact, a common misconception is that camera lenses will cut out UV and you have to use a quartz lens if you wish to 'see' UV, but the truth is that there is a lot of UV coming through even a camera lens unless it specifically is designed with a UV cutoff and that is in the manufacturers specs.

We used to have a lot of problems when taking high altitude photos with normal lenses and through normal glass or plexiglass. The UV gets pretty bad at high altitudes.

In fact, as a side note, Kodak manfuactured a set of HA (High Altitude) filters in sets of 3 good up to about 100,000 ft or so.

This brings up the reason for my point above.

Displays in sunlight at altitudes such as in Denver differ in UV blocking requirements than displays in sunlight at sea level. This difference is not insignificant. Therefore, different types of glass or plexiglass would be indicated based on locale (altitude).

PE
 
So there are plastics that would be suitable for UV exposure printing...? I am thinking of using a large piece of glass or maybe plastic for larger than 11 x 14 platinum prints, instead of a frame. Maybe a heavy (like 1/2 inch or so plastic would work, (If i get plastic suitable for the correct wave length) -- Is that what Helen is saying -- excuse me I am a retired trumpet player--thanks
Dave in Vegas
 
Although I have not seen specs on standard glass or acrylic UV filtering capabilities I do know that Cyro UV filtering is superior to glass. UV filter glass and acrylic both run at least 97% however it is just a coating on glass. Depending on the manufacture of the glass, and treatment of the piece over time, the coating can fade and or be removed. In the case of acrylic, the UV filter is built into the substrate so it can never be removed. For both glass and acrylic you will end up with a yellow tint if it has UV filtering applied. Glass will also have the green tint which is reduced on glass such as TruVue Museum glass.
 
At the level Helen is talking about, I agree that she is ... well, I hesitate to use the adjective "absolutely"... correct - but she is damned close to it. One always can make statements intended to satisfy low-level generic parameters, and when ground fine, doors are opened for further discussion.

Photo ... are you sure you intended to write "quartz"? I haven't seen many optical components, other than those intended for use with lasers - made from crystalline quartz - as opposed to fused quartz (i.e., the material used in optical flats). "Cut out" (?) UV -- remove ALL UV? No... but, a LOT. When the desired effect is to remove a LOT MORE UV, filtration is a good way to go.

When I get a free moment, I'll find that Hasselblad Catalog listing the "Designed Specifically for UV" lens. I dislike making statements at this level form memory.

BTW - Glass CAN be formulated to attenuate more UV by itself - It does not have to be a "coating".
 
DeanC said:
This one actually looks pretty interesting.
Click to expand...

I visited the "Surmet" web site. The "trade name for this is "ALON".

This is interesting "stuff" - Very nearly "transparent" to UV while filtering out a LOT of Infra-Red.
A tad on the "expensive" side, though. Just a tad.

Is it my imagination, or are the indices of refraction VERY high? My memory banks are admittedly worn - but aren't these higher than - even - quartz?
 
Ed;

My quartz reference comes from the fact that Nikon makes a quartz glass lens (very expensive) for UV photography. At least I hope so, or my memory is really slipping on this one.

Did I get this backwards?? I'll have to look it up.

PE
 
I dunno if the ALON stuff would be useful in a lens, but a ground glass that could deflect a rifle bullet would be pretty cool.
 
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