Many formulation issues are often discovered late in development — during stability testing, scale-up, or even after launch. When something goes wrong, the instinct is usually to troubleshoot reactively – adjust a level, swap an ingredient, or add “one more thing” to fix the problem.
But in practice, many of these challenges are shaped much earlier, long before the first batch is made. They are often rooted in how the formulation system was designed in the first place.
This is where functional ingredients play a central role. They are not just supporting components around actives – they are the backbone that determines structure, stability, sensory experience, and ultimately how well a product performs over time.
Starting with the experience, not the ingredient list
Before choosing ingredients, it helps to step back and define what the product is meant to feel like and how it should behave.
Is the texture light or rich? Is the viscosity fluid, lotion-like, or thick and cushiony? How quickly should it absorb? What kind of after-feel should it leave on skin?
These sensory and functional decisions shape almost every technical choice that follows. Consumers experience a product through touch, spread, scent, and appearance long before any long-term benefits from actives are noticed. If these aspects are not planned intentionally, it becomes much harder to correct them later.
Designing with the final experience in mind creates a clearer framework for ingredient selection, rather than hoping performance emerges after the fact.
Functional ingredients as the system architecture
Functional ingredients such as emulsifiers, oils, solvents, rheology modifiers, humectants, preservatives, surfactants creates the structure of a formula. They determine whether an emulsion is stable, how it flows, how it feels on application, and how it responds to processing and storage.
When these ingredients are treated as the backbone of the formulation, troubleshooting becomes more logical. Instead of reacting to problems as isolated events, it becomes easier to trace them back to system-level decisions.
Actives, in this context, are not separate from the system. They participate within it. Even when brands choose actives early due to trends or marketing priorities, understanding the system around them allows formulators to design the formula intentionally and troubleshoot logically, rather than reacting to unforeseen issues later.
Ingredient selection as a consequence, not a starting point
Trends or brand requests often influence formulation direction. A particular active may be in demand at high percentages, and the format is sometimes fixed early based on marketing expectations.
However, not every active is suited to every format at every level. For example, high levels of niacinamide come with specific pH preferences, ionic strength considerations, and interactions with other ingredients. Designing a system around these constraints is very different from adding an active into an existing base and hoping it integrates smoothly.
When the system is designed first — including pH range, texture, and processing approach — ingredient selection becomes more intentional. In some cases, it may even prompt a reconsideration of format, which can prevent significant troubleshooting later on.
Understanding constraints makes issues easier to identify
Every ingredient comes with limitations. These are not flaws; they are simply part of how materials behave.
Some ingredients are sensitive to temperature and perform best when added during cool-down. Others require heating to dissolve or activate properly. Certain materials need neutralisation, while others are incompatible with alkaline conditions.
Understanding these boundaries early — pH range, thermal sensitivity, shear tolerance, and processing behaviour — makes it much easier to interpret issues when they arise, rather than treating them as unexpected failures.
Processing is part of the formula
Processing is often treated as a standard step: heat both phases, combine, homogenise, cool. While this is broadly accurate, the details matter more than they are often given credit for.
Which phase is added to which? At what temperature? How much shear is applied, and for how long? When are sensitive ingredients introduced?
Even ingredients described as “water-soluble” can behave differently depending on order of addition. Allantoin, for example, dissolves more efficiently when introduced into water before the addition of high levels of humectants such as glycerin. Adding it later into a more complex system can reduce its solubility and make it appear as though something has gone wrong, when in reality the system environment has changed.
For structured systems such as lamellar emulsions, processing becomes even more critical. Excessive shear or prolonged homogenisation can disrupt the very structures that give these systems their desirable sensory properties. Droplet size, mixing time, and temperature profiles all influence the final architecture of the formula.
Some problems only appear much later
Not all formulation challenges are immediately visible.
Preservation issues often emerge during challenge testing, even when a broad-spectrum preservative has been selected. Preservatives do not work in isolation — their effectiveness depends on pH, solubility, and how they interact with the surrounding ingredients.
Similarly, colour changes such as browning may not appear during early development. Browning can result from fragrance components like vanillin, or from certain actives such as ascorbic acid, especially when oxidation pathways are not adequately supported. Without understanding the system context, it can be difficult to pinpoint the source once the issue appears.
Performance testing can reveal similar surprises. Higher levels of UV filters do not automatically translate to higher SPF, and true protection is only confirmed during SPF testing. Film formation, distribution, and the overall formulation structure all influence the final result.
These delayed outcomes highlight why early design matters. When the system supports ingredient behaviour, late-stage issues become easier to interpret and address.
Designing so troubleshooting becomes logical
The goal of formulation is not to memorise fixes for specific problems. It is to design systems with intent, so that when challenges arise, they can be approached thoughtfully rather than reactively.
When functional ingredients are treated as the backbone of the formula, and when constraints, processing, and performance expectations are considered early, troubleshooting becomes a process of understanding relationships rather than trial and error.
Formulation rarely fails because of a single ingredient. More often, it reflects how the system was designed, understood, and processed as a whole. A well-designed formula is a cohesive system where each ingredient has a clear functional role, and the final product performs as intended.
