The reason why the lights in a UVLED curing machine turn blue or white has to do with the materials and processes used to manufacture the lamp beads. Specifically:
Blue light: When electrons combine with holes in a UVLED curing machine, a UV spectrum is produced. This portion of the UV light is located in the adjacent visible wavelength band, resulting in the blue color of the light that people see. In addition, UVLED curing machines may also be designed to emit blue light in order to alert the user that the equipment is in working order and to be safe. This design helps prevent users from being exposed to UV light for extended periods of time.
White Light: The white light emitted by some UVLED curing machines is actually generated by a single-band UV light source at 365/395nm. When this UV light source passes through air or other optical reactions, its edges produce a violet/blue spectrum of 435/545nm. These spectra mix together to eventually form the white light that one sees.
In summary, the color of light emitted by a UVLED curing machine is related to how it works and what it is designed for. Regardless of whether blue or white light is emitted, users should be safe when using them, avoid prolonged direct exposure to the light, and follow the manufacturer's operating instructions.