Cosmetic chemist Lei Smith, founder of Leitin Skincare, joins Skin Anarchy to pull back the curtain on formulation: what barrier repair really means, how to tell if an active is actually dosed to work, why price rarely signals quality, and why hyperpigmentation is so hard to treat.
How did Lei Smith get into cosmetic chemistry?
Through curiosity and a string of passions. A former banker turned landscape gardener, Smith started formulating as a hobby about six years ago after struggling to find skincare that worked for him. "It's like an endless, you can never know everything. And I love that about it," he says of the field that finally held his focus.
Why does he keep his brand out of retail?
To protect the quality of his formulas. Smith explains that retail forces formulations down to roughly 10 to 15 percent of the selling price, leaving little room for real ingredients. "In order for me to keep formulations where people get good value... I have to do it in house," running his cost of goods near 30 percent instead.
What does barrier repair really mean?
More than slathering on ceramides. Smith stresses that barrier health is tied to lifestyle, stress, and finding the right formula for your skin type, not a single hero ingredient. "It's not a specific set of ingredients," he says, noting a popular ceramide cream might dry his own skin out, and that skincare should be revised every decade.
How can you tell if an active is dosed to actually work?
Often by the math behind the price. Smith notes a $30 toner built on a 15 percent cost of goods contains under $4 of ingredients, which limits what can truly be inside. "Just because the cosmetic product is expensive... that is definitely not the case," he warns, since price misleads in both directions.
Does skincare need a penetration system to work?
For many actives, yes. Smith says peptides and other actives often struggle to cross the skin, so a serum should make its delivery method clear. "I wouldn't buy a peptide serum if it wasn't in some type of" penetration system, he says, pointing to encapsulation, liposomes, or carriers like urea as what separates a working formula from a hopeful one.
Can you use copper peptides with vitamin C or acids?
Keep them apart from pure vitamin C, with nuance. Smith explains that low pH acids can disassociate the copper and cause inflammation, and that the caution around vitamin C applies mainly to ascorbic acid. "I would definitely keep it away from ascorbic acid, but when it comes to derivatives, there is no data," he says, so he plays it safe given the cost.
Why is hyperpigmentation so hard to treat?
Because it runs across many pathways at once. Smith breaks it down: UV creates oxidative stress, inflammation degrades collagen, and melanocytes must be controlled at several steps, from tyrosinase to pigment transfer. "There's not a product really out there" that hits all of them, he says, which is why calming inflammation early matters as much as targeting melanocytes.
Does a higher price mean better skincare?
No, and the assumption costs consumers. Smith is blunt that expensive does not equal effective, and that cosmetic chemists formulating in house often beat retail on value. "If I was led by price, I wouldn't produce a good formula," he says, because he formulates for efficacy first and prices second.
How can consumers spot real value in skincare?
Look for a visible difference and read the label. Smith and the host agree good skincare should show a result, and that buzzy peptide names parked at the bottom of an ingredient list signal very low doses. His advice is to stop trusting brand prestige and start reading formulations, because efficacy, not packaging, is what delivers.
Listen to the full episode with Lei Smith of Leitin Skincare on Skin Anarchy, available wherever you get your podcasts.