Waterproof and Transfer-Resistant Claims: Film Formers аnd Testing

Waterproof and transfer-resistant are two different claims, they are delivered by different mechanisms, and they are substantiated by different tests. Brands routinely write both on the same pack after a single laboratory check, and the result is a claim that survives an enquiry only until someone asks which test supported which word. Understanding what separates the two is the difference between a defensible pack and an expensive relabelling.

This article covers why the two claims are not interchangeable, how a film former actually turns a wet layer into a resistant film, the main film former families and what each one contributes, why the emulsion type decides water resistance before any film former is chosen, how transfer resistance is a different property from water resistance, what the plasticiser does and why getting it wrong causes both failure modes, how each claim is tested, and what the tests do not prove.

Waterproof and transfer-resistant are not the same claim

Water resistance is about what happens when the film meets water. A film resists water when it does not swell, lift or break when it is immersed or sprayed, which depends on the polarity of the film and on the continuity of the layer across the skin. A water-resistant film can still transfer onto a collar, because a collar is a mechanical contact rather than a water exposure.

Transfer resistance is about what happens when something touches the film. A film resists transfer when its adhesion to the skin is stronger than its affinity for the contacting surface, and when the film itself is cohesive enough not to split. A film that transfers very little can still be washed away in seconds if it has no water resistance.

The third related property is sebum resistance, which is often what the customer actually means when they complain. A film can resist water and still break down in oil, and since the face produces oil continuously, a film that is not resistant to sebum will fail on the face even when it passes both of the other tests. The three properties are related but they are not substitutes for one another, and a claim has to name the one it means.

How a film former actually works

A film former is a polymer that is dissolved or dispersed in the vehicle and becomes a continuous solid layer as the vehicle evaporates. It works in three stages: it flows onto the skin with the vehicle, it loses the volatile fraction, and it forms a cohesive network that binds the pigment and adheres to the surface. Failure at any stage leaves either a film that never sets or a film that cracks.

The two properties that matter most are the glass transition temperature and the molecular weight. A polymer with a glass transition well above skin temperature gives a hard, resistant film that can feel tight and can crack if it is not plasticised. A polymer with a low glass transition gives a soft film that feels comfortable and transfers readily. The useful film formers sit in a window where the film is hard enough to resist but plasticised enough to move with the skin.

The carrier matters as much as the polymer. A film former delivered in a volatile silicone dries fast and leaves a light, even film; the same polymer delivered in a heavy oil never fully sets because the oil stays in the film and keeps it soft. This is why a formulation that adds a film former to an existing emollient-rich base rarely achieves the transfer resistance the brief asked for.

The main film former families

Acrylate copolymers are the workhorse of transfer-resistant colour. They adhere well to skin, resist water reasonably, and are available in a wide range of glass transition temperatures. Their weakness is that they can be tacky during the set and that they are sensitive to the oil content of the formula, which can keep them soft.

Silicone resins, particularly trimethylsiloxysilicate and its combinations with a dimethicone crosspolymer, give excellent water repellency and a dry, non-tacky feel, and they are the standard choice where water resistance is the primary claim. They are more expensive and they need a volatile carrier to be delivered properly, and they can feel tight if the level is pushed up.

Vinyl pyrrolidone copolymers, including the classic vinyl pyrrolidone and vinyl acetate copolymer and the PVP family, give good adhesion and a strong hold and are widely used in mascara and in long-wear colour. They are water-soluble or water-dispersible, which makes them easy to remove and also limits their water resistance unless they are combined with a water-repellent resin.

Polyurethanes appear mostly in mascara and in long-wear eye products, because they combine flexibility with a strong film and can be designed for specific water and oil resistance. Shellac and rosin esters are traditional and give a hard, glossy film with excellent transfer resistance, at the cost of brittleness and of a tendency to be sensitive to alkali.

Water resistance starts with the emulsion type

A water-in-oil emulsion resists water inherently, because the continuous phase is oil and water does not readily mix into it. Before any film former is added, the water-in-oil format has a structural advantage that an oil-in-water format does not, and the entire brief follows from that decision.

An oil-in-water emulsion needs a film former to resist water, and the film former has to survive the evaporation of the water phase and remain continuous. This is achievable, and many water-resistant mascaras and foundations are oil-in-water systems with a carefully chosen acrylate or silicone resin, but it demands a higher film former level and a lower oil content than the same product would need in a water-in-oil format.

The category of application sets the practical limit. An eye product can accept a water-in-oil system with a high volatile content because the area is small and the sensory expectations are different from a foundation. A full-face foundation in a water-in-oil format with a high film former load can feel heavy across a whole face, which is why the water-resistant foundations that feel comfortable are usually built on a lower film former level with a very efficient polymer rather than on a high level of an average one.

Transfer resistance is adhesion and cohesion together

The first half of transfer resistance is adhesion to skin. It comes from the polymer chemistry and from a clean, dry substrate — a formula applied to skin that still carries a moisturiser has a weak interface, which is why a transfer-resistant product can fail for a user with a rich skincare routine and pass for a user without one. This is a real and unavoidable variable, and it is why panel instructions for a transfer test specify a prepared skin condition.

The second half is cohesion of the film itself. A film that splits in the middle transfers part of its thickness onto the contacting surface even if the bond to the skin is strong. Cohesion comes from the polymer network and from the pigment loading, and a very high pigment load in a thin film reduces cohesion because there is less polymer between the particles.

The third factor is oil resistance. The film has to resist the sebum that arrives on the face, because oil softens the polymer and weakens both the adhesion and the cohesion. Silicone resins resist oil well; acrylate copolymers vary; vinyl pyrrolidone polymers are poor. On oily skin, a formula that passes a transfer test in a dry laboratory can fail after two hours of normal wear, and the test conditions have to reflect that.

The plasticiser problem

Every hard film needs a plasticiser, and the plasticiser is the ingredient most often responsible for both failure modes. A film former without a plasticiser becomes brittle, cracks at the first movement and flakes visibly. A film former with too much plasticiser never becomes hard enough to resist transfer and rubs off on contact.

The correct level is found by testing rather than by calculation, because the plasticiser efficiency depends on the polymer and on the rest of the oil phase. A common mistake is to count the emollient in the formula as the plasticiser and then to add a separate softener, which over-plasticises the film and produces the unexpected result of a product that cracks and transfers at the same time.

The plasticiser also affects the level of comfort. A film that is properly plasticised moves with the skin and feels like nothing; a film that is under-plasticised feels tight and the customer notices it within minutes. Since the customer notices discomfort before they notice a transfer result, the sensory and the performance targets have to be balanced in the trial rather than one optimised and the other accepted.

How each claim is tested

Water resistance is tested by exposing the film to water under defined conditions and measuring what is left. For a product making a strong water-resistance claim, the usual approach is immersion in water at a stated temperature for a stated time, with the colour or the effect measured before and after. A spray test is also used where the intended exposure is rain or sweat rather than swimming, and the exposure conditions are part of the claim rather than incidental to it.

Transfer resistance is tested by a controlled contact with a standard substrate under a defined load for a defined time, with the amount transferred read as a colour difference on the substrate. The substrate, the load, the contact time and the number of contacts are all specified in advance, because a light press and a firm rub produce different results and both can honestly be called a transfer test.

The measurement has to be on a defined area with a calibrated instrument rather than by eye. A visual assessment of a white collar can rank two samples, but it cannot produce a number, and a claim supported by a ranking is weaker than one supported by a measurement. Colour difference readings on a standard substrate give a number that can be reported and repeated.

Panel wear testing runs alongside. A defined number of volunteers, a defined application method, a defined set of time points and a defined set of environments — with photographs under a fixed light — is what turns a laboratory number into a wear duration. A claim of a number of hours needs panel data at those hours, not an extrapolation from a laboratory result.

What the tests do not prove

A laboratory test does not prove behaviour on every skin type. Sebum production varies enormously between individuals, and the panel composition determines what the result actually means. A wear claim tested on ten people with normal skin is not evidence for a wear claim on oily skin, and a brand targeting a broad market needs a panel that reflects it.

A test also does not prove removal behaviour, which is the other half of the claim. If a film is resistant enough to survive a day of wear, it is resistant enough to be difficult to remove, and a product that resists water will not come off with water. The removal method has to be defined and communicated, and the removal test is part of the substantiation because a product that cannot be removed safely is a different kind of problem.

Finally, a test does not prove stability over the shelf life. The film former and the plasticiser can separate or migrate over months, and a freshly made sample that passes can be a different product after a year in a warm warehouse. Stability testing in the final pack has to run alongside the performance testing rather than after it, and the pack compatibility work is a separate discipline covered in our guide to cosmetic packaging compatibility testing.

Writing the claim so it matches the test

The most robust claim is the one written from the test rather than the test designed for the claim. If the test immerses the sample for a defined period, the claim can state that period. If the test uses a defined contact under a defined load, the claim can describe the behaviour under contact. A claim that states a duration has to be supported at that duration, and a claim that states a condition has to be supported under that condition.

Comparative claims carry a higher burden because they assert a relationship. A claim of better transfer resistance than a competitor requires a comparison run under identical conditions on both products, and a comparison run under different conditions supports nothing. Where the brand wants a comparative claim, the comparison has to be built into the test design from the start rather than added afterwards.

Superlatives and absolute terms are the riskiest of all, because they can be read as applying to every condition. A claim that a product does not transfer at all is difficult to support and easy to disprove with a single counter-example. The usual discipline is to describe the measured behaviour rather than to assert an absolute, and the same principle applies to shade range documentation in our guide to foundation shade range manufacturing.

Removal, and why it belongs in the brief

Removal is a formulation property and it is decided at the same time as the resistance. A film that resists water and sebum will generally need an oil-based cleanser, because a water-based one cannot wet the film. A film built on water-soluble vinyl pyrrolidone polymers is easy to remove with water but has limited resistance. The two requirements pull against each other and the balance is a design decision rather than an afterthought.

The communicating part is as important as the formulating part. If the product needs a specific removal method, the pack or the product page has to say so, because a customer who cannot remove a long-wear product is a customer who damages their skin trying. The removal instruction is part of the product specification rather than a piece of marketing copy, and it should be signed off with the formula.

There is also a safety dimension. An eye product with strong water and oil resistance has to be removable without mechanical trauma, and a lip product with a long wear claim has to be removable without stripping the lip. Where the resistance target and the removal requirement cannot both be met comfortably, the resistance target is the one that is usually reduced.

Film former variables at a glance

The table below maps the main variables in a water-resistant or transfer-resistant brief to the property each one controls and the failure that follows when it is set wrongly. The values are comparative rather than fixed, because the right combination depends on the product type, the emulsion and the claim being made.

The table is a relative picture rather than a rule for any single market. Each value is read against the product type, the emulsion and the claim being made, and the combination is only settled once the film has been tested under the conditions the claim will describe.

What to put in the brief

• Which claim is being made, water resistance, transfer resistance or both, as they are separate.
• The exposure the claim refers to, whether swimming, rain, sweat or contact with fabric.
• The duration the claim will state, so the test can be designed at that duration.
• The product type, because eye, lip and full-face products carry different practical limits.
• The skin type of the target user, since sebum resistance is not covered by a water test.
• The removal method the product will require, agreed at the same time as the resistance target.
• The pack and the compatibility testing needed to hold the film over the shelf life.
• The markets of sale, so the claim substantiation and the labelling follow from the start.

Where our capability fits

We build a long-wear product from the film outward, because the resistance claim is a property of the polymer network rather than of any single ingredient. The emulsion type is decided first, the film former is selected for the property being claimed, the plasticiser is balanced against the sensory target in the trial rather than after it, and the claim language is written from the test that was actually run.

We work with brands on private label (your brand on a proven base), OEM/ODM contract manufacturing, and full custom formula development — whichever matches where your brand is today. Our lines include a long-lasting waterproof sweat-proof foundation, an anti-static leave-in spray and a vitamin E serum softgel, all of which are built on the same film former, volatile carrier and compatibility disciplines that a waterproof or transfer-resistant programme draws on.

Tell us the claim, the exposure and the duration you intend to write, and we will map the film system, the plasticiser balance and the test design against your own brief. Start at our inquiry page, email capsulebiotech@163.com, or message the right team on WhatsApp: Capsule Series (capsules only) +86 158-7655-5319, Cosmetics Series (serum, hair care, body care, fragrance) +86 158-7655-5319.

General manufacturing information, not regulatory or legal advice. Claim substantiation requirements, permitted wording and cosmetic claims vary by market and by product.