Coated vs clear?

what is the difference between coated and clear lights? i assume clear is where its at from journals i have read, but could coated be cooler? or is there no difference at all? lazy Saturday, happy growing!!

Coated will likely be hotter, and the total internal reflection will be greater, trapping some light in the bulb which will convert to heat. They also emit less light, though the light can be tuned to more useful spectra.

TeaTreeOil said:

Coated will likely be hotter, and the total internal reflection will be greater, trapping some light in the bulb which will convert to heat. They also emit less light, though the light can be tuned to more useful spectra.

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Depends on the coating. If the internal (even external) coating is an anti reflective, then more light will get through.

4 major optic properties:
Absorption
Reflection
Refraction
Transmission.

the white coating on the inside of a cfl makes the light visible otherwise it would just emit in the ultra violet range

Well, the coatings typically absorb specific frequencies, and fluoresce specific frequencies. This is not a 100% effective process, as more light is absorbed than fluoresced. There is also a small degree of reflectivity. Transmittance is usually fairly low, like fluoros, which transmit less than 7-8% of the original UV used to excite the phosphors.

The total net photon flux is dimished; however, the photosynthetic photon flux density(PPFD) could very well be increased.

I believe the OP is talking about HID(likely MH) bulbs. For all I know it could be incandescents.

it was truly a wide open question i hope some of these answers helped