Plexiglass -G UVT

• will pass UVB
• Is used in tanning beds
• Is used as covers for some pet cages

Should be useful as a window ‘’glass’’ for you or your pet.

Plexiglass -G UVT can also be used to make a "heat shield" to get vitamin D from the sun without getting too hot.

Just need to add a coating to it.
to absorb/reflect some of all of the UVA and IR portions of the spectra
so that a person could get vitamin D from the sun without getting a tan (UVA) or getting too hot (IR).

At a minimum the coating could just reduce the IR
A better costing would block all of the IR
The best coating would stop UVA and IR but pass the visible light
An acceptable coating would stop everything above UVB: UVA, visible, and IR

Spectra for mirror coatings: derived from Wikipedia

The combination should reduce 90% of the light and virtually all of the heat
VitaminDWiki added UVB spectra

It appears that a mirror made of Plexiglass G-UVT coated with silver (Ag) might make an acceptable coating
All of the UVA, visible, and infrared would be reflected, and only the UVB would pass thru the mirror.
Video on how to add a silver coating using chemicals by http://angelgilding.com/
Mirrors can also be made with very thin silver leaf attached to the "glass" with gelatin - see PDF attached at bottom of this page - also by http://angelgilding.com/
The gelatin might absorb the UVB - not sure need to check Google Images
Can protect the chemical or leaf silver by sandwiching it between two layers of plexiglass
5 square feet of silver leaf costs as little as $8 and shipping
Would need at least 4 packages (20 square feet) to make a silver plexiglass mirror large enough to provide just UVB to an adult.

Neat features of this heat shield

• Get vitamin D (UVB) with minimal tanning (no UVA)
• Possibly get 4X as much vitamin D per minute than if in the direct sun
  (UVA, which seems to cancel some vitamin D production, is blocked by the heat shield)
• Can spend more minutes in the sun when you do not overheat (especially good for those with dark skins)

Plexiglass datasheets are attached at the bottom of this page

UV transmission by standard window glass

No UVB (Vitamin D) gets thru, but most UVA (Tan) gets thru

See also VitaminDWiki

• UVA decreases vitamin D
• UVA from some tanning beds and most windows decrease vitamin D blood levels – March 2012
• Business opportunity – you can now make stuff which only passes vitamin D wavelength

See also web

• Example supplier on internet $25/square foot Dec 2015

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Methacrylate glass also transmits in the UVB (update May 2020)

Spectral transmission of solar radiation by plastic and glass materials
Would still need to use silver to block the heat and brighness of the sun

Available from Lowe's, etc.
 Download the PDF from VitaminDWiki

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