For conformal coating, Philips Lumileds has performed some tests using various materials but has not come to a conclusion whether it is safe or not to use conformal coating with LUXEON LEDs. The challenge is that there might be certain chemicals in the coating material that may interact with the LED package and damage it. If you need to coat the board, you will have to qualify a material through several testing cycles to make sure that the performance of the LEDs is not affected by the coating process/material. Some attempts of conformal coating have worked fine, however I cannot say for sure that every process will work out. A list of chemicals that should not come in contact with the LED package is listed in Application Brief AB32: http://www.futurelightingsolutions.com/en/Technologies/Semiconductors/Lighting-Solutions/High-Power-LED-Emitters/White/Pages/7102577-LXML-PWN1-0100.aspx?ManufacturerName=PHILIPS-LUMILEDS&isFLS=true