Master Class: Reformulating E-Liquids for Ceramic Coils – A deep dive into Viscosity, Wickability, and Flavor Dynamics

Author: R&D Team, CUIGUAI Flavoring

Published by: Guangdong Unique Flavor Co., Ltd.

Last Updated:  Feb 28, 2026

Micro-Level Ceramic Wetting

In the fast-moving landscape of vapor product development, the only constant is evolution. As the industry shifts from traditional fiber-wicked atomizers (cotton, silica) toward advanced porous ceramic heating elements—driven by demands for consistency, pure flavor, and device longevity—manufacturers of finished electronic liquids face a critical engineering challenge.

Legacy formulas, optimized for the rapid, high-absorption capillary flow of organic cotton, often fail when introduced to ceramic systems.

This mismatch does not merely affect user experience; it causes catastrophic failures: “dry hits,” premature coil burnt taste, and leaking due to poor saturation or improper sealing.

As a premier global manufacturer of advanced fragrances and flavor concentrates for electronic liquids, we understand that flavor excellence is inherently tied to physical chemistry. Success in the modern market requires more than just mixing. It requires reformulation with intent, focused on the complex interplay of viscosity, thermal dynamics, and flavor compound volatility within porous media.

This comprehensive technical guide explores the science behind reformulating e-liquids specifically for ceramic heating elements, providing actionable insights for e-liquid mixologists and production managers.

Part 1: The Material Science of Wicking – Cotton vs. Ceramic

To understand how to reformulate, we must first analyze the fundamental difference in physical wicking mechanisms between the “old guard” and the “new standard.”

1.1 Traditional Wicks (Cotton/Cellulose)

Traditional wicking uses natural or synthetic fibers arranged linearly or randomly.

• Mechanism:Capillary action occurs in the microscopic gaps between the fibers.
• Characteristics:Extremely fast absorption rate. It acts like a sponge, quickly soaking up liquid regardless of high viscosity.
• Drawback:It degrades rapidly under high temperatures, holds “flavor ghosts” (residual flavor from previous fills), and is prone to hot spots.

1.2 Porous Ceramics

Advanced ceramic wicks are engineered from materials like Silicon Carbide (SiC) or alumina, which are synthesized through a sintering process to create a rigid, porous matrix.

• Mechanism:True capillary flow within an interconnected, microscopic pore structure. The liquid moves through the solid material via its empty internal voids.
• Characteristics:Highly precise control over pore size and distribution, exceptional heat resistance (eliminating burnt cotton taste), and material chemical inertness.
• Drawback:Significantly higher resistance to fluid flow compared to open-fiber networks. The absorption is methodical and relies heavily on fluid dynamics.
• The Crucial Formula Deviation:Because ceramic wicks are inherently “slower” to saturate than cotton, standard high-VG (Vegetable Glycerin) formulas (e.g., 70VG/30PG or 80VG/20PG) often cannot reload the ceramic pores quickly enough after a draw, leading to dry hits even though the tank appears full.

Part 2: The Core Challenge – Deciphering Viscosity and Flow

Viscosity, simply defined, is a fluid’s resistance to flow (its internal friction). It is the single most critical physical property when reformulating for ceramic coils.

2.1 The Dynamic and Kinematic Split

In reformulation, we must consider two types of viscosity:

• Dynamic (Absolute) Viscosity (μ):Measure of internal resistance (often measured in centipoise, cP).
• Kinematic Viscosity (ν):Measure of resistive flow under gravity (ν = μ / density).

In vapor dynamics, we focus heavily on dynamic viscosity.

• Propylene Glycol (PG):≈ 42 cP at 25°C.
• Vegetable Glycerin (VG):≈ 1,400+ cP at 25°C.

VG is hundreds of times more viscous than PG. Small shifts in the VG/PG ratio radically change the overall viscosity of the e-liquid.

2.2 The Viscosity-Temperature Relationship

It is essential to understand that viscosity is not constant. It drops dramatically as temperature increases. For instance, VG’s viscosity plummets from 1,400 cP at room temperature to roughly 100 cP at just 60°C.

Ceramic coils excel here. Because they hold residual heat well, they reduce the viscosity of the liquid immediately surrounding them during a vaping session. However, for the initial draw (“cold start”) or chain-vaping (rapid successive draws), the room-temperature viscosity is the limiting factor. If the liquid in the tank cannot reach the ceramic, the ceramic burns the liquid remaining in its pores.

A standard benchmark used by device manufacturers for reliable wicking in typical 1.0–1.5 Ω ceramic pod systems is a dynamic viscosity between 20 cP and 80 cP at ambient temperature (25°C). Standard 70VG formulas are often 150 cP or higher.

According to research shared by the American Chemical Society, the physical properties, including viscosity, of PG/VG mixtures deviate significantly from ideal behavior, meaning simple linear calculations do not always apply when additives (flavors) are included [^1].

Viscosity Pouring Comparison

Part 3: Mastering Wickability via Surface Tension and Pore Size

If viscosity is “resistance to movement,” wickability is the “ease with which a liquid saturates a porous solid.” It is governed by the Washburn Equation, which describes capillary flow in porous materials:

The Strategy: To maximize wicking speed (increase L over time t), you must decrease viscosity (η), increase pore radius (r, determined by hardware design), decrease the contact angle (θ, improve “wetting”), or increase surface tension (γ, although this is complex as it counteracts wetting).

3.1 Wettability (θ)

This is the attraction between the liquid and the ceramic surface. If the ceramic is “hydrophobic” to your e-liquid formula, the liquid will bead up, creating a high contact angle and resisting wicking.

Some ceramic formulas require specialized surfactant-like compounds within the e-liquid to reduce this contact angle and ensure immediate, complete saturation upon contact.

3.2 Dynamic Pore Utilization

High-VG liquids often experience “pore blocking.” The large VG molecules cannot easily enter the smaller pores of the ceramic matrix. This effectively reduces the active wicking area of the coil. Reformulating to a lower viscosity allows the fluid to utilize 100% of the engineered pores.

Part 4: Flavor Chemistry – Volume, Volatility, and Viscosity Interactions

As a fragrance manufacturer, this is where our expertise becomes paramount. Flavor concentrates are not just aromatic markers; they are chemical diluents that radically affect the base fluid mechanics.

4.1 Concentration Dynamics (Muting vs. Amplification)

Ceramic coils are known for producing exceptionally clean flavor, but they generally vaporize less liquid volume per puff than cotton-wicked sub-ohm tanks.

The Counter-Intuitive Approach: When reformulating a formula (e.g., a complex dessert flavor) from a cotton 70/30 base to a ceramic-friendly 50/50 base, you might expect you need more flavor because you lowered the volume of VG (the primary vapor carrier).

However, because the 50/50 liquid wicks faster, the ceramic can run more efficiently and at lower temperatures without burning. The flavor is often perceived as stronger or “purer” because the high-viscosity “shield” (VG) is reduced, allowing the top and middle aromatic notes to volatilize more cleanly. We often recommend a slight reduction in flavor load (5–10% decrease) when moving to a high-PG base to avoid over-saturation of flavor and potential chemical harshness.

4.2 Volatility Management and Boilers

Ceramic coils heat up methodically and maintain a more stable thermal envelope than cotton. This affects the “flash-off” sequence of your flavor compounds.

• Low-Boiling Point Esters (Fruits, Citrus):In traditional cotton setups, these might vaporize too quickly, disappearing on high-wattage hits. On ceramic, they volatilize more gracefully.
• High-Boiling Point Ketones/Phenols (Creams, Tobaccos, Custards):On cotton, these often require high heat that risk burning the cotton wick itself. Ceramic can maintain the high temperatures needed to fully “unlock” these notes without scorching.

Therefore, reformulating for ceramic is an opportunity to adjust the flavor profile to be more nuanced, utilizing higher concentrations of high-boiling point compounds that were previously too difficult to vaporize effectively in low-power cotton systems.

4.3 Understanding Aromatic Thinning

Most flavor concentrates are solubilized in a PG base. When you add 15% flavor to an e-liquid, you are not just adding aroma; you are adding 15% PG diluent. This radically drops the viscosity.

When developing fragrances for ceramic, we engineer specific solvent blends (often including PDO – Propanediol, a thinning alternative) to manage the thinning effect while maintaining flavor solubility. For a ceramic formulation, the flavor concentrate itself should be designed to be as “thin” (low cP) as possible to assist in the overall formula’s flow [^2].

Ceramic Pore Flow Visualization

Part 5: Step-by-Step Guide to Reformulating for Ceramic Systems

This methodology is used by our technical consultants to help clients transition their product lines.

Phase 1: Establish the Target Viscosity

• Benchmark the Base:Start by testing the current failure point. If your 70VG formula is dry-hitting, test its ambient viscosity. You likely need to drop from ~150 cP to below 100 cP.
• Adjust the VG/PG Ratio:The most effective lever.
• For standard pod systems (1.2Ω): Move from 70VG/30PG toward 50VG/50PG or even 40VG/60PG (high PG is often preferred for salt nicotine stability and rapid flow).
• For high-power ceramic systems (CBD/Distillate):High VG is rarely compatible; reformulation requires almost entirely PG, PDO, or specialized thinning agents (which we provide).

Phase 2: Diluent Optimization

• Use High-Purity Diluents:Always use USP/EP grade PG and VG. Impurities in VG can increase viscosity and introduce microscopic particulates that clog ceramic pores.
• Explore PG Alternatives:If a client requires a smoother hit than standard PG, we may suggest Propanediol (PDO). PDO has slightly different viscosity-temperature curve dynamics and surface tension properties than PG, which can sometimes improve wetting in stubborn ceramic formulas.
• Manage Total Solids:Be mindful of formulas with high sugar contents (sweeteners like sucralose) or highly complex, dense flavor compounds. These can leave carbon deposits (“gunk”) inside the ceramic matrix. While ceramic can withstand burn-offs that would destroy cotton, minimizing gunk through flavor reformulations (reducing sweeteners) is crucial for coil life.

Phase 3: Flavor Re-Profiling

• Re-balance Flavor Load:Do not assume a simple reduction of total flavor percentage. Instead, re-profile the relative ratios within the flavor concentrate.
• Strategy:Increase the ratio of middle and base notes (the high-boiling point compounds) and slightly reduce top notes (low-boiling esters). This leverages the ceramic’s thermal stability.
• Eliminate Essential Oils:Some organic fragrance lines use natural essential oils. These are rarely compatible with ceramic due to extremely high boiling points, potential residue, and difficult wick-saturation characteristics. Move exclusively to optimized aroma chemicals and flavor fractions.

Phase 4: Wicking and Stability Testing

• The Ambient Flow Test:Measure viscosity at 25°C. For standard e-liquid pods, aim for 40 cP – 80 cP [^3].
• The “Cold Start” Dry Hit Test:Place a filled device in a refrigerator at 4°C for 30 minutes. Take the first draw immediately. If the coil burns, the viscosity at lower temperatures is still too high. The liquid around the coil cannot flow in quickly enough. You must increase the PG ratio or utilize a viscosity modifier.
• The Stability Stress Test:Cycle the filled device between extreme heat (35°C) and cold (4°C). This tests for leaking (viscosity dropped too far under heat) and crystallization/precipitation (flavor compounds dropping out of solution under cold).

Conclusion: Engineering Excellence Over “Trial and Error”

Reformulating for ceramic coils is not a matter of guesswork; it is a critical engineering challenge that demands a deep understanding of fluid dynamics, material science, and flavor chemistry. Relying on legacy high-VG formulas in modern ceramic hardware is a strategy for market obsolescence, resulting in frustrated consumers and compromised product quality.

As a dedicated manufacturer of high-performance fragrances and flavor concentrates for the vapor industry, we provide more than just ingredients. We are your technical partners in this transition.

Our analytical laboratories are equipped to measure dynamic viscosity, surface tension, and volatile aroma profiles under thermal stress. We engineer flavors from the molecular level up to ensure they not only taste exceptional but possess the physical characteristics required for precise, efficient operation within porous ceramic systems.

By embracing the science of reformulation, your brand can unlock the true potential of ceramic technology: unparalleled flavor purity, unprecedented consistency, and enhanced consumer trust. The market has shifted. Your formulations must shift with it.

Ceramic Optimized Product Hero Shot

Transform Your Product Line: Partners in Ceramic Compatibility

Don’t let legacy formulations hold back your brand’s hardware potential. If your products are struggling with dry hits, burnt taste, or leaking in modern ceramic systems, we are ready to assist.

We provide customized technical consultation, advanced viscosity analysis, and a comprehensive library of fragrance concentrates engineered specifically for ceramic compatibility.

Take the First Step:

• Technical Exchange:Let’s schedule a call with our flavor chemists and material scientists to discuss your specific hardware compatibility challenges.
• Request Free Samples:Experience firsthand the difference a ceramic-optimized flavor concentrate can make in flow, stability, and taste.

Contact Us Today:

Citations

[^1]:

“Properties of Propylene Glycol and Glycerol Mixtures and Implications for E-Cigarette Users,” an analysis found in peer-reviewed contexts such as ACS Chemical Health & Safety or presented at relevant chemical conferences.

[^2]:

Data on volatile organic compounds and carrier solvent interactions, referenced from databases like the Flavor and Extract Manufacturers Association (FEMA) or the Good Scents Company Information System.

[^3]:

Benchmarks for dynamic viscosity (centipoise, cP) are derived from collaborative research between e-liquid mixology laboratories and leading global ceramic heating element manufacturers (e.g., Smoore/CCELL, ALD, or similar industry engineering whitepapers).