Mechanisms and Troubleshooting of Foam Reduction in Personal and Household Care Formulations: Film Rupture, Weak Interfacial Films, Insufficient Surfactant Supply, and Phase-State Disturbance

1 The Essence of Foam Reduction: Disruption of the Foam Stabilization Process

In personal and household care formulations such as shampoos, body washes, hand soaps, dishwashing detergents, and hard-surface cleaners, foam performance is often directly perceived by consumers and is also commonly used by formulators to assess the state of a formulation system. During product development, a common observation is that even when the surfactant content has not been significantly reduced, the addition of fragrances, essential oils, silicone oils, solvents, oils, salts, or conditioning agents can lead to a clear decrease in foam volume, coarser foam texture, or rapid foam collapse after foaming. In most cases, this occurs because certain raw materials alter the interfacial structure, liquid-film strength, surfactant distribution, or phase state on which foam generation and stabilization depend. Foam formation involves at least two processes:

Process	Main meaning	Key indicators
Foaming ability	Whether the system can rapidly generate a large amount of air/liquid interface during stirring, rubbing, or impact	Initial foam height, foaming speed, foam volume
Foam stability	Whether the foam films that have already formed can resist drainage, coarsening, coalescence, and rupture	Foam retention, half-life, foam fineness

A decrease in foaming performance may appear in two different ways: either foam is difficult to generate, or foam forms but breaks quickly. Difficulty in foam generation is often related to dynamic surface tension, surfactant diffusion rate, and effective surfactant concentration. Rapid foam breakage after formation is more often related to foam-film elasticity, foam-film drainage, rupture caused by hydrophobic oil droplets, electrolytes, and changes in phase state.

2 Stable Foam Requires Three Key Supports

2.1 Surfactants Must Rapidly Reach Newly Formed Interfaces

When a product is rubbed, pumped, or rinsed, air is incorporated into the system and a large amount of new air/liquid interface is generated instantly. Surfactants need to migrate quickly to these new interfaces and reduce dynamic surface tension so that newly formed bubbles do not immediately coalesce.

If the system contains a high proportion of polyols, a high-viscosity oil phase, solvents, or surfactants with low dynamic adsorption ability, the rate of new interface formation may exceed the rate at which surfactants can protect the interface. As a result, bubbles can coalesce during the early stage of formation, leading to slow foaming and low foam volume.

2.2 Foam Films Must Have Sufficient Interfacial Strength

The thin liquid films between bubbles are not simply layers of water. They are thin-film structures composed of water, surfactants, micelles, salts, polymers, and other additives. Stable foam films require a certain degree of interfacial viscoelasticity and the ability to repair surface-tension gradients.

When a foam film becomes locally thinner, differences in surfactant distribution at the interface can create a surface-tension gradient, causing liquid to flow back toward the weakened area. This repair effect is related to interfacial elasticity, surface-tension gradients, and Marangoni flow, and is also often discussed together with Gibbs elasticity. The stronger the interfacial-film viscoelasticity and self-repairing ability, the less likely the foam is to rupture.

If an added raw material loosens the interfacial film, reduces its elasticity, or weakens the repulsive forces between bubble surfaces, foam may still form, but it is more likely to become large, coarse, and rapidly defoamed.

2.3 Surfactants Must Retain Sufficient “Effective Supply Capacity”

The total amount of surfactant added to a formulation is not equal to the effective surfactant supply that is actually available for foaming and foam stabilization. This effective supply includes not only free surfactant monomers, but also micellar reservoirs that can rapidly dissociate, migrate, and replenish the air/liquid interface, as well as the portion of surfactant not occupied by oils, fragrances, essential oils, silicone oils, soils, cationic polymers, hard-water ions, or electrolyte-induced phase-state changes.

For example, fragrances require surfactants for solubilization, oily soils require surfactants for emulsification, cationic polymers may form complexes with anionic surfactants, and calcium and magnesium ions in hard water may form insoluble compounds with fatty acid soaps. All of these factors reduce the surfactant supply available to the air/liquid interface and therefore decrease foam.

3 Direct Film-Rupture Factors: Defoamers, Silicone Oils, Fragrance Oils, Essential Oils, and Hydrophobic Oil Droplets

3.1 Defoamers Reduce Foam by Disrupting Foam-Film Structure

Defoamers are direct foam-reducing raw materials. Effective defoamers usually have three characteristics:

Characteristic	Significance for foam reduction
Incomplete compatibility with the aqueous phase or surfactant system	Allows the material to exist as small oil droplets or hydrophobic particles
Low surface tension or spreading ability	Makes it easier to enter the air/liquid interface or foam-film region
Ability to create local weak points	Triggers foam-film drainage, bridging, dewetting, and rupture

Common defoamers include polydimethylsiloxane-based silicone oil defoamers, silicone oil/hydrophobic silica composite defoamers, mineral-oil defoamers, polyether defoamers, and polyether-modified silicone defoamers. The combination of silicone oil and hydrophobic silica is commonly used because the oil phase helps the defoamer enter the foam film, while the hydrophobic particles help induce bridging and dewetting.

Excessive addition of a defoamer does not necessarily further improve defoaming efficiency. Too much defoamer may cause oil floating, turbidity, deposition, reduced stability, or loss of the effective film-rupturing state after being fully emulsified by a strongly emulsifying system.

3.2 Whether Oil-Phase Raw Materials Reduce Foam Depends on Whether They Form a Free Hydrophobic Phase

Silicone oils, limonene, vegetable oils, mineral oils, ester oils, oil-soluble actives, oily fragrances, and essential oils may all reduce foam. The key is whether these hydrophobic components can contact the foam film in the form of free oil droplets or weakly stabilized oil droplets. The destructive effect of oil droplets on foam usually involves the following process:

Process	Result
Oil droplets enter the foam film	The oil phase comes into contact with the air/liquid interface
Oil droplets spread or deform at the interface	The local composition and tension of the foam film change
Oil droplets bridge the two sides of the foam film	The thin liquid film is locally pulled thinner
The foam film dewets or ruptures	Bubbles coalesce and the foam collapses

Whether an oil phase causes significant foam reduction depends on oil-droplet size, oil/water interfacial tension, surfactant type, emulsification state, oil-phase viscosity, and dosage. If the oil phase is sufficiently solubilized, its direct film-rupturing effect may be weakened. However, the solubilization process consumes surfactants and may also reduce foam. In other words, an oil phase may reduce foam either through “film rupture” or through “surfactant consumption.”

3.3 Fragrances and Essential Oils Are Used at Low Levels, but Often Have a Significant Impact on Foam

Oily fragrances and essential oils are usually added at low levels in personal and household care formulations, but their impact on foam should not be overlooked. This is because they are often multi-component hydrophobic mixtures containing terpenes, esters, alcohols, aldehydes, ketones, and other components. Some of these components may have strong interfacial activity or hydrophobic spreading ability. Fragrances and essential oils mainly reduce foam through three pathways:

Pathway	Mechanism
Free oil droplets rupture the foam film	Fragrance oil droplets that are not fully solubilized enter the foam film and induce rupture
Free surfactant is consumed	Surfactants are used to solubilize the fragrance, reducing the surfactant available to the air/liquid interface
The interfacial-film structure is altered	Fragrance components insert into the surfactant film, loosening the foam-film arrangement

Limonene is a typical example. It is a hydrophobic terpene compound and is often used as an oily cleaning aid or fragrance component. If the formulation lacks an appropriate solubilization or emulsification design, limonene can easily form a hydrophobic dispersed phase, thereby exerting a clear foam-suppressing effect.

4 Weak Interfacial-Film Factors: Low-Foaming Surfactants and Some Nonionic Surfactants

4.1 The Low-Foaming Characteristics of Some Low-Foaming Surfactants Come from Differences in Foam-Film Stability

Some nonionic surfactants have good wetting, emulsifying, penetrating, and detergency properties, but relatively low foam. Examples include fatty acid methyl ester ethoxylates (FMEE) and some EO/PO block polyethers, which are commonly used in low-foaming cleaning, machine washing, hard-surface cleaning, and industrial cleaning systems.

Many low-foaming nonionic surfactants have strong wetting and emulsifying abilities. The core reason for their low-foaming behavior is that they can reduce interfacial tension, but the foam films they form may not have sufficient elasticity, strength, and resistance to drainage. Compared with typical high-foaming anionic surfactants, some nonionic surfactants lack obvious charge repulsion, so the electrostatic repulsive force between the two sides of a foam film is weaker. If surface coverage is insufficient or the interfacial-film elasticity is inadequate, the foam film is more likely to become thinner and coalesce.

4.2 The Foam Performance of EO/PO Block Polyethers Is Related to Structure and Temperature

EO/PO block polyethers consist of hydrophilic ethylene oxide segments and relatively hydrophobic propylene oxide segments. By adjusting the EO/PO ratio, molecular weight, block structure, and end groups, products with different performance profiles can be obtained, ranging from wetting, emulsification, and solubilization to low foaming, foam control, and foam suppression. Not all EO/PO block polyethers have the same low-foaming behavior. Their foam performance should be evaluated based on EO/PO ratio, molecular weight, end-group structure, temperature, and the combined formulation system. The foam performance of this type of surfactant is usually affected by the following factors:

Structural or environmental factor	Effect on foam
Higher proportion of PO segments	Hydrophobicity increases, foam-film stability may decrease, and some structures show low-foaming or foam-control characteristics
Changes in molecular weight and block arrangement	Dynamic adsorption, interfacial-film structure, and micellar behavior change
Temperature rising close to the cloud point	Nonionic hydration decreases, and the system becomes more prone to turbidity or phase separation
Changes in the blending ratio with anionic surfactants	May enhance or weaken the high-foaming characteristics of the original system, depending on the blending ratio and phase state

The cloud point is the characteristic temperature at which a nonionic surfactant solution changes from clear to turbid during heating. When the system approaches or exceeds the cloud point, the hydration layer of the nonionic surfactant weakens, and its dissolution state and interfacial arrangement change. Foam stability usually decreases under these conditions.

4.3 The Foam Performance of Potassium Soaps Is Strongly Affected by System Conditions

Potassium soaps are potassium salts of fatty acids. Some potassium soaps can generate relatively abundant foam under suitable chain length, suitable pH, and soft-water conditions. In particular, in traditional soap-based cleansing systems, potassium soaps are not necessarily low-foaming. Foam reduction in potassium soap systems usually occurs under the following conditions:

Condition	Cause of foam reduction
High levels of calcium and magnesium ions in hard water	Formation of insoluble calcium or magnesium fatty acid salts
Decreased pH	Fatty acid salts convert into free fatty acids, reducing solubility
High proportion of long-chain fatty acids	Solubility worsens at low temperature or high salt levels
High oil or soil load	Surfactants are consumed for emulsification and soil removal
Excessive electrolytes	Dissolution state and micellar structure are disrupted

5 Decrease in Effective Surfactant Concentration: Conditioning Agents, Oily Soils, and Component Interactions

5.1 Cationic Polymers and Quaternary Ammonium Salts May Reduce the Free Concentration of Anionic Surfactants

Cationic conditioning agents are often added to shampoos, body washes, and fabric care products. Examples include cationic guar gum, polyquaterniums, and quaternary ammonium softeners. These materials can improve smoothness, wet combability, deposition feel, and conditioning performance, but they may also affect foam.

The main reason is that cationic components may interact electrostatically with anionic surfactants, forming complexes or aggregates. Moderate complexation can promote deposition of conditioning agents, but excessive complexation reduces the amount of free anionic surfactant. This can leave insufficient surfactant available for foaming, resulting in lower foam volume, coarser foam, or turbidity in the system.

5.2 Oily Soils and Sebum Can Cause Foam to Decrease Rapidly in Actual Use

Foam performance in personal and household care products cannot be evaluated only through pure-water testing. In actual use, sebum, scalp oil, makeup, sunscreen, dishwashing grease, and particulate soils all consume surfactants. Oily soils reduce foam mainly for two reasons:

Cause	Manifestation
Surfactants shift toward the oil/water interface	The amount of surfactant available for the air/liquid interface decreases
External oily soils form oil droplets and enter the foam film	The foam film is disrupted by the hydrophobic phase

This is why some cleaners produce abundant foam in blank water, but foam decreases rapidly when heavy oily soil is present. In this case, foam reduction does not necessarily indicate poor cleaning performance. Instead, the surfactants are being used to emulsify, disperse, and detach oily soils.

6 Solvents and Polyols: Effects on Surfactant Adsorption, Diffusion, and Foam-Film Stability

6.1 Ethanol and Glycol Ether Solvents Alter Surfactant Adsorption and Foam-Film Structure

Ethanol, isopropanol, ethylene glycol monobutyl ether, propylene glycol ethers, and other solvents are commonly used to improve solubility, degreasing power, drying speed, or low-temperature stability. Their effects on foam mainly arise from changes in the properties of the continuous phase, surfactant dynamic diffusion, and interfacial-film viscoelasticity. Common effects include:

Effect	Impact on foam
Changes in aqueous-phase polarity	Surfactant dissolution, micellization, and adsorption behavior change
Changes in the critical micelle concentration, or CMC	Free monomer surfactant concentration and interfacial adsorption rate change
Effects on foam-film viscoelasticity	Resistance of the foam film to drainage and disturbance decreases
Enhanced dissolution of oils or fragrances	Surfactants redistribute between the oil/water interface and the air/liquid interface
Volatilization causing local concentration changes	Foam-film thickness and surface-tension distribution fluctuate

When ethanol content is relatively high, foam in the system usually decreases because ethanol changes the hydration environment and interfacial arrangement required for surfactants to form stable foam films. Short-chain alcohols and glycol ether solvents are generally more likely to weaken foam. Fatty alcohols, however, are not necessarily solvent-type foam-reducing factors. In some surfactant systems, fatty alcohols may instead improve foam stability by strengthening the interfacial film or forming lamellar structures.

6.2 Glycerol Is Not a Typical Defoamer

Glycerol is a water-soluble polyol mainly used for moisturization, skin feel adjustment, and modification of aqueous-phase properties. Its effect on foam is usually related to dosage and system composition:

Glycerol level or system state	Possible performance
Low to moderate addition level	Limited effect on foam; in some systems, foam fineness may improve
High addition level	Aqueous-phase viscosity and water activity change, surfactant diffusion slows, and foaming becomes slower
Coexisting with high oil phase or high fragrance level	Surfactant distribution becomes more complex, and foam may decrease
Combined with a suitable surfactant system	Foam retention may improve due to slower drainage

By changing aqueous-phase viscosity, the hydration environment, and surfactant dynamic diffusion, glycerol may affect foaming speed and foam stability. The direction of its effect depends on its addition level and formulation structure.

7 Phase-State Disturbance Factors: Salt, Hard Water, pH, and Temperature

7.1 Foam Reduction Caused by Excessive Salt Is Essentially the Result of Electrolytes Changing Micellar Structure and System Phase State

Salt is commonly used as a thickener in personal and household care systems, especially in systems based on sodium laureth sulfate, or SLES, combined with cocamidopropyl betaine, or CAPB.

Salt has a dual effect on foam. An appropriate amount of salt may increase system viscosity, slow foam-film drainage, and improve foam retention. Excessive salt, however, may cause viscosity drop, turbidity, phase separation, reduced surfactant solubility, or weakened repulsion within the foam film, ultimately leading to foam reduction. A typical salt curve can be summarized as follows:

Salt-addition stage	System change	Possible foam performance
Low-salt region	Micelles are smaller and viscosity is lower	Foam retention is generally moderate
Appropriate-salt region	Charge screening is moderate, micelles grow, and viscosity increases	Foam retention may improve
Excessive-salt region	Micellar structure changes excessively, viscosity decreases, or phase state becomes unstable	Foam decreases, becomes coarse, and may even become turbid or phase-separated

Foam reduction caused by salt usually occurs after excessive addition, after the system’s tolerance limit is exceeded, or after phase-state changes are triggered. The effect of salt is also related to surfactant type, active matter concentration, temperature, pH, and the presence of other electrolytes.

7.2 Hard-Water Ions Reduce the Effective Surfactant Level in Soap-Based and Some Anionic Systems

Calcium and magnesium ions in hard water can significantly affect foam, especially in fatty acid soap systems. Calcium and magnesium ions readily react with fatty acid salts to form insoluble calcium or magnesium fatty acid salts, causing soap scum, deposition, and loss of effective surfactant. Hard water can also affect some anionic surfactants to varying degrees. The strength of this effect depends on surfactant structure, hardness level, chelation system, and the total salt content of the formulation.

In actual use, if a product foams well in deionized water but shows reduced foam in hard water, the following factors are often involved:

Cause	Result
Calcium and magnesium ions react with fatty acid soaps	Insoluble soap scum forms and foam decreases
Calcium and magnesium ions affect the micellar or dissolution state of some anionic surfactants	Surfactant effectiveness and foam performance decrease
Surfactants are jointly consumed by soils and hard-water ions	Less surfactant is available at the air/liquid interface
Deposits enter the foam film	Foam fineness and stability worsen

7.3 pH Changes the State of Fatty Acid Soaps and Amphoteric Surfactants

pH is an important variable affecting foam. For fatty acid soaps, a decrease in pH converts fatty acid salts into free fatty acids. Free fatty acids have poor water solubility, and their interfacial behavior and micellar behavior change, so foam in the system usually decreases. For amphoteric surfactants, pH affects their charge state, thereby influencing their synergistic foaming, thickening, and mildness performance with anionic surfactants. For example, CAPB has different charge states at different pH values, and its blending effect with SLES may also change.

7.4 Temperature Affects the Cloud Point of Nonionic Surfactants and the Dispersion State of Oil Phases

An increase in temperature reduces the hydration ability of some nonionic surfactants, causing them to approach their cloud point and increasing the tendency toward turbidity or phase separation. For nonionic surfactants such as EO/PO block polyethers and fatty alcohol ethoxylates, temperature changes may significantly alter foam performance.

Temperature also affects oil-phase viscosity, fragrance volatilization, micellar structure, and salt-thickened systems. In some systems, foam may be normal at room temperature but decrease after high-temperature storage or during use with hot water. This may not indicate surfactant failure; instead, it may result from changes in nonionic hydration, oil-phase dispersion, or electrolyte-related phase state.

8 Formulation Troubleshooting: How to Determine Which Type of Cause Is Responsible for Foam Reduction

When foam decreases, the first step is to distinguish whether the problem occurs during the foaming stage or the foam-stabilization stage. The next step is to determine whether the cause is film rupture, surfactant consumption, weak interfacial film, or phase-state change. In personal and household care formulations, defoamers, low-foaming surfactants, oil-phase raw materials, fragrances, essential oils, solvents, glycerol, salts, hard-water ions, pH, temperature, and conditioning agents may all affect foam.

Observation	Possible cause	Suggested verification method
Foam is difficult to generate from the beginning	Slow dynamic adsorption, insufficient effective surfactant, high proportion of solvents or polyols	Measure initial foam height, foaming after dilution, and dynamic surface tension
Foam collapses quickly after formation	Insufficient foam-film elasticity, oil-droplet rupture, excessive salt	Measure foam retention at 1 min, 5 min, and 10 min
Foam decreases after fragrance is added	Fragrance oil droplets rupture the foam film or consume surfactant	Conduct fragrance-gradient testing, blank fragrance control, turbidity observation, and centrifugation observation
Foam decreases after salt addition following initial thickening	Salt curve exceeds the suitable range	Conduct a salt-gradient curve and record viscosity, foam height, and transparency at the same time
Foam becomes significantly worse in hard water	Calcium and magnesium ions consume surfactants or form precipitates	Compare deionized water with standard hard water
Foam decreases during hot-water use or after high-temperature storage	Nonionic surfactants approach the cloud point, or oil-phase/micellar structure changes	Conduct temperature-gradient foam testing and appearance observation
Foam becomes coarser after conditioning agents are added	Excessive complexation between cationic components and anionic surfactants	Conduct conditioning-agent gradient testing, dilution turbidity testing, and foam-fineness comparison
Foam decreases rapidly in the presence of oily soil	Surfactants are consumed by oily soil or oil droplets rupture the foam film	Conduct foam-retention testing under oily-soil load

Foam-reduction pathway	Representative factors	Core mechanism
Direct film rupture	Defoamers, silicone oils, fragrance oils, essential oils, limonene	Hydrophobic oil droplets or particles enter the foam film, inducing bridging, dewetting, and rupture
Weak interfacial film	FMEE, EO/PO block polyethers, some low-foaming nonionics	Surface tension can be reduced, but foam-film elasticity and drainage resistance are insufficient
Surfactant consumption	Oily soils, fragrances, oils, cationic polymers, hard-water ions	Free surfactant decreases, leaving insufficient surfactant supply for the air/liquid interface
Phase-state disturbance	Excessive salt, pH shift, temperature increase, cloud-point change	Micelles, solubility, viscosity, and interfacial structure change
Change in aqueous-phase environment	Ethanol, glycol ethers, high levels of glycerol	Surfactant diffusion, adsorption, hydration, and foam-film viscoelasticity change

9 Classification Tables of Representative Chemicals Related to Foam-Reduction Mechanisms in Personal and Household Care Formulations

Table 1 Defoaming/Foam-Suppressing Materials, Hydrophobic Oil Phases, and Oily-Soil Model Materials

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Silicone oil foam-suppression model	63148-62-9	S433164	Silicone oil	Viscosity 5 cSt (25°C)	Used to study the entry of silicone oil-type hydrophobic phases into foam films, local spreading, foam-film rupture, and foam decay behavior
Mineral-oil hydrophobic oil phase	8042-47-5	P104807	Liquid paraffin	Heavy, density: 0.86–0.89	Used in experiments on the effects of mineral oil phases on surfactant distribution, oil-droplet-induced film rupture, and foam retention
Polyether foam-suppressing component	25322-69-4	P103212	Polypropylene glycol (PPG)	Average molecular weight 4000	Used to study the influence of hydrophobic polyether segments on low-foaming systems, foam-film drainage, and foam-suppression performance
Phosphate ester defoaming model	126-73-8	T100707	Tributyl phosphate (TBP)	AR, ≥99%	Used in experiments on the effects of hydrophobic phosphate esters on foam-film stability, defoaming efficiency, and foam lifetime
Particle film-rupture model	112945-52-5	S124829	Fumed silica	Hydrophobic type, specific surface area (BET): 300 m²/g	Used to study the effects of solid particles on foam-film bridging, interfacial disturbance, drainage, and rupture behavior
Vegetable oily-soil model	8001-22-7	S1456046	Soybean oil	USP, natural, European Pharmacopoeia (Ph. Eur.), refined	Used to simulate surfactant consumption, oil-droplet entry into foam films, and foam reduction under oily-soil load
Vegetable oil/fat model	8001-31-8	C113014	Coconut oil	Chemically pure (CP)	Used to study the effects of oil/fat load on soap-based systems, free surfactant distribution, and foam stability
Light oil/fat model	73398-61-5	M1456050	Medium-chain triglycerides	USP, European Pharmacopoeia (Ph. Eur.)	Used to study the effects of light oil phases on emulsification demand, surfactant occupation, foam-film drainage, and foam decay
Ester emollient oil phase	110-27-0	I109490	Isopropyl myristate	≥98	Used to study the effects of ester oil phases on surfactant distribution, foaming speed, foam-film stability, and oil-phase compatibility
Terpene fragrance oil phase	5989-27-5	L106923	(R)-(+)-Limonene	≥95%, contains 0.03% alpha-tocopherol as stabilizer	Used in experiments on the effects of terpene hydrophobic components on fragrance solubilization, foam-film rupture, and foam retention
Terpene mixed oil phase	138-86-3	D106755	Dipentene	≥95%	Used to study the effects of terpene mixtures on surfactant solubilization demand, free oil droplets, and foam decay behavior

Table 2 Surfactants, Low-Foaming Surfactants, and Soap-Based System Materials

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Block polyether nonionic surfactant / thermosensitive polyether model	9003-11-6	K434429	Kolliphor® P 407	Ethylene oxide content 71.5–74.9%	Used to study thermosensitive micelles, solubilization, gelation, emulsion stabilization, and interfacial behavior of nonionic block polyethers
Secondary alcohol ethoxylate nonionic surfactant	84133-50-6	T476408	TERGITOL™ 15-S-15	Nonionic surfactant	Used in experiments on dynamic adsorption, wetting and detergency, interfacial-film strength, and foam retention of nonionic surfactants
Fatty acid methyl ester ethoxylate low-foaming surfactant	65218-33-7	F304287	Fatty acid methyl ester ethoxylate	68–71%	Used to study the wetting, detergency, easy-rinsing, and foam-decay behavior of low-foaming nonionic surfactants
Anionic high-foaming reference surfactant	151-21-3	S432157	Sodium dodecyl sulfate (SDS)	Anhydrous, ACS, ≥99%	Used in experiments as a foaming-performance reference and to study salt effects, hard-water effects, foam-film stability, and surfactant blending
Main anionic surfactant for personal cleansing systems	9004-82-4	S196294	Sodium laureth sulfate	≥25%	Used in experiments on foam in personal cleansing systems, salt-thickening curves, blending with amphoteric surfactants, and foam retention
Amphoteric synergistic surfactant	61789-40-0	C665446	Cocamidopropyl betaine	Actives content 28–32% in water	Used to study synergistic foaming and thickening with anionic surfactants, foam fineness, and pH effects
Medium-chain fatty acid potassium salt	10124-65-9	P731198	Potassium laurate	≥98%	Used in experiments on the effects of fatty acid chain length on foaming power, foam fineness, and hard-water sensitivity in soap-based systems
Unsaturated fatty acid potassium salt	143-18-0	P118571	Potassium oleate	≥98%	Used to study foaming power, oily-soil load, hard-water deposition, and foam stability in unsaturated soap-based systems
Long-chain fatty acid potassium salt	2624-31-9	P1062057	Potassium palmitate	≥98%	Used in experiments on solubility, acid–base conditions, hard-water effects, and foam reduction in long-chain soap-based systems
Long-chain saturated fatty acid potassium salt	593-29-3	P112436	Potassium stearate	AR, ≥98%	Used to study the solubility and foam performance of long-chain fatty acid salts under low-temperature, high-salt, and hard-water conditions

Table 3 Solvents, Co-Solvents, and Aqueous-Phase Modifiers

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Short-chain alcohol aqueous-phase solvent	64-17-5	E111989	Ethanol	Guaranteed reagent, water ≤0.3%	Used to study the effects of short-chain alcohol proportion on aqueous-phase polarity, dynamic surface tension, surfactant hydration, and foam-film lifetime
Short-chain alcohol degreasing solvent	67-63-0	I112011	Isopropanol (IPA)	AR, ≥99.7%	Used in experiments on the effects of short-chain alcohols on surfactant adsorption, oily-soil dissolution, foam-film drainage, and foam retention
Glycol ether degreasing solvent	111-76-2	E110825	Ethylene glycol monobutyl ether (EB)	PureSpectra™, spectroscopic grade, ≥99%	Used to study the effects of glycol ether solvents on oil-phase dissolution, surfactant distribution, interfacial-film strength, and foam decay
Diethylene glycol ether co-solvent	112-34-5	B110650	Diethylene glycol monobutyl ether	≥99.5%, for surfactant analysis	Used to study surfactant analysis systems, degreasing cleaning systems, and the effects of glycol ether co-solvents on foam performance
Propylene glycol ether co-solvent	34590-94-8	D108833	Dipropylene glycol methyl ether	≥98%	Used in experiments on the effects of glycol ether solvents on fragrance solubilization, oil-phase compatibility, the surfactant working environment, and foam retention
Aromatic alcohol co-solvent	100-51-6	B108202	Benzyl alcohol	Anhydrous, ≥99.8%	Used to study the effects of aromatic alcohols on fragrance solubilization, preservative-system compatibility, surfactant distribution, and foam changes
Aromatic ether alcohol preservative aid	122-99-6	E109370	Phenoxyethanol	≥99%	Used in experiments on preservative aids, fragrance co-solubilization, oil-phase compatibility, and effects on foam stability
Hydrotrope	1300-72-7	S485589	Sodium xylenesulfonate solution	Mixture of isomers, 40 wt.% in H₂O	Used to study hydrotropy, fragrance solubilization, system transparency, surfactant distribution, and foam performance
Polyol humectant	56-81-5	G755728	Glycerol	Anhydrous, UltraBio™, molecular biology grade, ≥99.5% (GC)	Used to study the effects of polyols on water activity, continuous-phase viscosity, surfactant dynamic diffusion, and foaming speed
Polyol solvent	57-55-6	P432968	1,2-Propanediol	Basic reagent, for preparation	Used in experiments on the effects of polyol solvents on continuous-phase properties, fragrance co-solubilization, surfactant diffusion, and foam retention
Polyol humectant model	50-70-4	S104837	D-Sorbitol	Ultrapure, ≥99.5% (HPLC)	Used to study the effects of high polyol levels on aqueous-phase viscosity, foam-film drainage, foaming speed, and foam fineness
Water-soluble polymer rheology model	25322-68-3	P615493	Polyethylene oxide	Viscosity 65–115 cps	Used to study continuous-phase viscosity, foam-film drainage rate, foam retention, and polymer-based foam stabilization

Table 4 Salts, Electrolytes, Hard-Water Components, and Chelating Materials

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Main electrolyte for salt-curve studies	7647-14-5	S433744	Sodium chloride	Anhydrous, high-purity, reagent grade, ≥99%	Used in experiments on salt-thickening curves, micellar growth, viscosity drop, foam retention, and foam reduction caused by excessive salt
Ionic-strength adjustment salt	7757-82-6	S639099	Sodium sulfate	Anhydrous, PharmPure™, ChP	Used to study the effects of inorganic-salt ionic strength on micellar structure, foam-film drainage, and foam stability
Hard-water calcium ion model	10043-52-4	C431202	Calcium chloride	Anhydrous, ≥97%	Used in experiments on the effects of calcium ions on fatty acid soap precipitation, hard-water tolerance of anionic systems, and foam reduction
Hard-water magnesium ion model	7791-18-6	M774658	Magnesium chloride hexahydrate	European Pharmacopoeia (Ph. Eur.), suitable for analysis, premium grade	Used to study the effects of magnesium ions on soap-based deposition, hard-water foam decay, foam-film stability, and surfactant effectiveness
Calcium/magnesium chelating agent	6381-92-6	E116428	Disodium EDTA dihydrate	AR, ≥98%	Used in experiments on calcium/magnesium ion complexation, hard-water tolerance evaluation, control of soap-based precipitation, and foam improvement
Buffering and complexing salt	6132-04-3	S116315	Sodium citrate dihydrate	Molecular biology grade, ≥99%	Used to study buffering systems, mild complexation, ionic-strength adjustment, and foam performance under hard-water conditions

Table 5 Acid–Base Adjustment, Neutralization, and Soap-Based System Preparation Materials

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Inorganic strong-base regulator	1310-73-2	S111498	Sodium hydroxide	Guaranteed reagent, ≥96%	Used to study acid–base condition adjustment, fatty acid saponification, anionic-system state, and foam changes
Alkali source for potassium soap preparation	1310-58-3	P431767	Potassium hydroxide	Anhydrous, ≥99.95% metals basis	Used to study potassium fatty acid salt preparation, acid–base conditions in soap-based systems, solubility, and foam performance
Organic base neutralizer	102-71-6	T478536	Triethanolamine	Reagent grade, ≥98%	Used to study organic-base neutralization, salt-form changes, formulation pH adjustment, and compatibility with surfactant systems
Organic acid regulator	77-92-9	C108869	Anhydrous citric acid	AR, ≥99.5% (T)	Used to study acidification, conversion of fatty acid soaps to free fatty acids, charge state of amphoteric surfactants, and foam reduction
Hydroxy acid regulator	50-21-5	L108839	DL-Lactic acid	AR, 85–90%	Used to study surfactant charge state, changes in soap-based systems, and foam stability under low-pH conditions

Table 6 Cationic Conditioning Materials and Materials Affecting Compatibility with Anionic Surfactants

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Cationic polymer conditioning agent	81859-24-7	P341830	Polyquaternium-10	Viscosity 300–500 mPa·s, 2% aqueous solution, 25°C	Used to study complexation between cationic polymers and anionic surfactants, conditioning-agent deposition, foam fineness, and changes in foam volume
Cationic surfactant compatibility model	112-02-7	C466513	Hexadecyltrimethylammonium chloride solution (HTAC)	25 wt.% in H₂O	Used in experiments on anionic/cationic compatibility, reduction of free anionic surfactant, turbidity formation, and foam reduction
Long-chain cationic conditioning agent	17301-53-0	N587655	N,N,N-Trimethyldocosan-1-aminium chloride	≥80%	Used to study long-chain cationic conditioning systems, softening deposition, complexation with anionic surfactants, and foam changes

Note: The products listed above are representative Aladdin products for scientific research and formulation-mechanism studies. The applications in the tables are mainly intended as references for mechanism verification, model experiments, and formulation research, and do not indicate that all products are suitable for direct use in final personal and household care formulations. Actual use should be comprehensively evaluated based on product grade, regulatory requirements, safety, odor, impurities, SDS, COA, and the specific application scenario. For more product specifications, grades, and COA information, please search by “product name/CAS/catalog number” on the Aladdin website.

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