Silicone allows impurities in the encapsulant to degrade the LED to failure. Glass lenses prevented this.
Anyone know of an LED manufacturing contact who can put glass lenses on?
I think you have been provided grossly inaccurate information.
Virtually every PC high powered LED is encapsulated in silicone. Impurities in the grade of silicone used for LED encapsulation are virtually non-existent. This is optical/semiconductor grade silicone that is used.
Silicone is currently about the only viable encapsulant. It withstands the very high temperatures of LED die at the extremes, i.e. 150C, it is an excellent binder for the phosphor, it does not yellow under intense blue and even near UV light, and most importantly it does not place undue mechanical strain on the bond wires, die, etc. that occur in the fairly extensive thermal shock that occurs with high powered LEDs.
Secondary lenses are either uv stabilized polycarbonate or PMMA, PMMA is almost always preferred as high quality optical PMMA only hazes about 10% after 100,000 hours of exposure to fairly significant levels of sunlight and its transmission rate is high, even compared to glass.
Glass secondary lenses are used, mainly for COB arrays as few companies have the ability to precision mould glass to the level required for for small optics.
I am not aware of any urethane encapsulation directly on LEDs, though I know there are people who have overmoulded LED arrays in urethane conformal coating for weather resistance, but good luck getting any LED vendors to approve that. Silicone conformal coating has also been used this way. You are betting to put on a secondary optic and seal the overall assembly.
Semiman