Lesson 1Active dosing plan: selecting an effective yet tolerable percentage range and rationaleThis section teaches how to set active levels that are effective yet tolerable. You will interpret literature, in vivo data, and regulatory limits, define starting ranges, and plan stepwise optimisation while managing cumulative exposure in routines.
Reading literature and supplier dataMinimum effective vs plateau dosesSafety margins and irritation thresholdsLayering with other products in a routinePilot batches and consumer feedback loopsLesson 2Solvents and co-solvents selection: water, glycols, propanediol, oils — impact on solubility and stabilityThis section focuses on choosing solvents and co-solvents such as water, glycols, propanediol, and oils. You will see how polarity, volatility, and miscibility affect solubility, stability, skin feel, and delivery of hydrophilic and lipophilic actives.
Water quality and microbiological controlUsing glycols to improve solubilityPropanediol as humectant co-solventOil phase choice for lipophilic activesSolvent impact on stability and feelLesson 3Emollients and skin-feel modifiers: lightweight esters, caprylic/capric triglycerides, squalane — balancing aesthetics and skin toleranceThis section examines emollients and skin-feel modifiers, including esters, caprylic/capric triglycerides, and squalane. You will learn to tune spreadability, richness, and afterfeel while supporting barrier function and active tolerability.
Lightweight esters for fast absorptionCaprylic/capric triglycerides as base emollientSqualane for barrier support and slipSilicone vs non-silicone feel strategiesComedogenicity and skin type matchingLesson 4Antioxidants and stabilisers to protect actives: vitamin E (tocopherol), ferulic acid, chelators (EDTA), and rationaleThis section covers antioxidants and stabilisers that protect sensitive actives from oxidation and degradation. You will study vitamin E, ferulic acid, chelators like EDTA, and how to design synergistic systems matched to formula type and packaging.
Oxidation pathways in cosmetic formulasVitamin E (tocopherol) in oil phasesFerulic acid to support vitamin C systemsChelators such as EDTA and alternativesPackaging and oxygen exposure controlLesson 5Humectants and moisturisers: role of glycerin, propanediol, sodium hyaluronate, butylene glycol and selection guidanceThis section explores humectants and moisturisers such as glycerin, propanediol, sodium hyaluronate, and butylene glycol. You will learn how to combine them to balance hydration, tackiness, penetration, and compatibility with actives.
Glycerin levels and tack controlPropanediol as mild humectant solventSodium hyaluronate grades and weightsButylene glycol for slip and solvencyHumectant blends for different climatesLesson 6Designing the serum type: water-based serum, emulsion serum, anhydrous serum — selection matrix based on chosen activeThis section guides selection of serum type based on active profile. You will compare water-based, emulsion, and anhydrous serums, using a decision matrix that weighs solubility, stability, sensory goals, packaging, and consumer expectations.
Water-based serums for hydrophilic activesEmulsion serums for mixed solubility needsAnhydrous serums for unstable activesDecision matrix by active and skin typePackaging choices for each serum typeLesson 7Thickeners and texture agents: carbomers, xanthan gum, polyacrylate rheology modifiers and considerations for clarity vs opacityThis section details how thickeners and rheology modifiers shape texture, spreadability, and suspension. You will compare carbomers, xanthan gum, and polyacrylates, and learn how to tune clarity, opacity, and sensory feel for different product formats.
Carbomer types and neutralization needsXanthan gum for natural, elastic texturesPolyacrylate rheology modifiers in gelsBalancing clarity, opacity, and viscosityPreventing syneresis and phase separationLesson 8pH adjusters and buffers: selection and how to control formula pH to protect actives and skin compatibilityThis section explains how to select pH adjusters and buffers to protect actives and skin. You will learn to choose acids, bases, and buffer pairs, measure and fine-tune pH, and prevent drift over shelf life and during consumer use.
Target pH ranges for key activesCommon acids and bases for adjustmentBuffer systems and ionic strengthpH drift causes and preventionpH measurement and calibration basicsLesson 9Preservative systems and strategies for low-irritancy formulas: preservative selection, boosting with chelators, and preservative compatibilityThis section explains preservative system design for low-irritancy formulas. You will compare common preservatives, boosting with chelators and humectants, and evaluate compatibility with pH, surfactants, and natural claims while meeting safety standards.
Regulatory limits and global preservative listsOrganic acids and pH-dependent systemsPreservative boosting with chelatorsSynergy with humectants and glycolsChallenge testing and risk assessmentLesson 10Penetration enhancers and delivery systems: role of solvents, short-chain alcohols, propylene glycol, esters, and encapsulation approaches (liposomes, solid lipid nanoparticles)This section explains how penetration enhancers and delivery systems work, covering common solvents, short-chain alcohols, glycols, esters, and modern encapsulation systems to improve active solubility, stability, and skin targeting while limiting irritation.
Role of solvent polarity in skin permeationShort-chain alcohols: efficacy vs irritationUse of glycols and propylene glycolEster-based penetration enhancersLiposomes and solid lipid nanoparticles
