Ever wondered what’s really triggering the cure in your LED UV lash adhesive? In this episode of Lash Science, we’re unpacking the most commonly used photo-initiators in the industry: TPO, TPO-L, TMO, BAPO, and CQ. We explain what they are, how they work, and our opinions on each—especially when it comes to eye safety, sensitivity, and yellowing. Whether you're a chemistry nerd or just want to know what’s in your glue, this one's for you.   List of Photo Initiators mentioned and their info: TPO: Ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate CAS #: 84434-11-7   TPO-L: Ethyl (2,4,6-trimethylbenzoyl)oxyphenylphosphinate CAS #: 75980-60-8   TMO: Methylene bis(1,4-cyclohexanediyl)(bis(2-(4-methylphenyl)-2-propyl)phosphine oxide) CAS #: 145052-34-2    (Note: TMO is less commonly listed by this name and may be referred to as a specialty phosphine oxide initiator. It’s sometimes proprietary.)   BAPO: Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide CAS #: 162881-26-7   CQ (Camphorquinone): 1,7,7-Trimethylbicyclo[2.2.1]heptan-2,3-dione CAS #: 10373-78-1   SSPI: Diphenyl(4-sodium phenylthio)phenyl sulfonium hexafluorophosphate CAS #: 72135-85-6