14. Inside the Bottle: Breaking Down Photo-Initiators in LED UV Lash Adhesives

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