At CeraLab, we believe in building formulations from the ground up — not just to create better products, but to understand the chemistry that drives performance. In our last post, we prepared a controlled set of carnauba-based wax blends to examine how the balance of hard and soft waxes affects usability, drying, and buffing behaviour.
This time, we turned our attention to solvents.
Solvents do far more than dissolve wax — they determine how a product feels during application, how quickly it dries to a haze, how easy it is to buff, and even whether the final film cures evenly or separates. These properties are deeply interconnected, but rarely predictable from boiling point or solvent name alone.
To explore this, we created a focused matrix of 12 samples, all using the same wax base, but with different solvents and addition levels. Our aim was simple: to learn what really happens when you tweak solvent volatility in a solvent-wax system — and to turn those lessons into something useful for training, formulation design, and further development.
What we found challenged a few assumptions — and helped reinforce others.
What We Tested
To isolate the effects of solvent choice, we kept the wax system consistent: a 70:30 ratio of solvent to a balanced 1:1 blend of paraffin and carnauba wax. This base gave us a reliable film with moderate hardness and gloss, allowing us to observe how each solvent influenced drying, application, and buffing without interference from formulation complexity.
We selected six solvents for this study, chosen to represent a broad range of evaporation rates, solvent chemistries, and industry relevance. Each solvent was tested at both a low addition level (3 g, balanced with 3 g odourless kerosene) and a high addition level (6 g), for a total of 12 samples. All samples were 25 g in total weight, using a uniform batch preparation method to maintain accuracy.
Here’s a breakdown of the solvents, their approximate boiling points, and why they matter in formulation work:
| Solvent | Boiling Point (°C, approx.) | Description | Industry Relevance |
| Heptane | ~98 °C | Fast-evaporating straight-chain hydrocarbon | Common in quick-dry spray waxes and panel wipes; good for degreasing and rapid flashing systems |
| Cyclomethicone | ~170 °C | Volatile silicone (typically D4/D5 blend) | Used in high-gloss detailers and trim dressings for its dry, residue-free finish |
| D-Limonene | ~175 °C | Natural terpene with strong solvency and scent | Found in eco-labelled cleaners and waxes; also used for its aggressive solvency and citrus fragrance |
| D40 | ~180 °C | Medium-drying aliphatic hydrocarbon | Standard solvent in paste waxes, polishes, and traditional detailers |
| D60 | ~220 °C | Slower-evaporating, low-odour aliphatic solvent | Preferred in hand-applied products requiring longer working time or soft cure |
| Isopar M | ~240 °C | High-purity, very slow-drying branched paraffin | Used in paste waxes and protective coatings for extended open time and improved gloss flow |
How the Tests Were Carried Out
Each sample was evaluated under consistent ambient conditions using simple, practical methods designed to reflect how these products behave in real-world use. While the approach was deliberately straightforward, the insights it offered were both reliable and highly relevant to formulation work.
After cooling, we began with a visual inspection. This allowed us to spot early signs of incompatibility — such as surface weeping, non-uniform textures, or gloss dulling. These observations often reveal more than numbers, offering clues about how well a solvent has integrated or whether it’s disrupted the wax structure during setting.
Hardness was then assessed by gently pressing a fingertip into the centre of the wax. Rather than relying on instrumentation, we used a standardised scale from 1 to 10, with 5.5 as the target for a buffable wax. This method, while tactile, reflects the real-world expectation: whether the surface feels soft, firm, brittle, or just right.
Application ease was tested using a foam applicator to spread each sample onto a clean panel. We judged each wax by how smoothly it spread, whether it resisted motion, and whether it tended to over-apply. While this is subjective, it maps closely to user experience and is especially useful when training others to recognise workable viscosity and slip.
To record dry time, we measured the interval between application and visible haze formation — the moment when the wax transitions from a wet film to a matte surface. This gives a good indication of flash-off behaviour and working time, both of which are critical for usability.
Finally, buffing performance was assessed 10 minutes after application. Using a clean microfiber towel and light pressure, we looked at how easily the wax lifted from the surface, how cleanly it broke away, and whether it left any residue or tackiness. This is one of the most telling measures of a wax’s overall behaviour — a formulation that applies and dries beautifully but refuses to buff cleanly will never satisfy the user.
Together, these tests provided a well-rounded view of how each solvent affected the wax system — not just in theory, but in practice.
Key Comparisons We Explored
Once the test results were in, we took a closer look at how solvent properties — particularly boiling point, addition level, and interaction with the wax matrix — influenced the performance of each sample. The findings highlighted several relationships worth examining, some of which challenged common assumptions around volatility and drying behaviour.
Boiling Point vs. Dry Time
At first glance, we might expect solvents with lower boiling points to evaporate faster, resulting in shorter dry-to-haze times. In reality, the opposite trend emerged. The slowest-drying samples weren’t always those with the highest boiling points. In fact, D60 and Isopar M, both high-boiling solvents, consistently produced some of the shortest haze times.
This tells us that boiling point alone is not a reliable predictor of drying performance in wax systems. Instead, factors like solvent-wax compatibility, diffusion rate, and the formation of a coherent wax film play a more significant role in determining when a sample is “dry enough” to buff.
Hardness vs. Buffing Ease
Samples with hardness values around 4.5–5.5 were generally the easiest to buff. Above or below this range, performance started to drop off. The hardest sample (D-Limonene, low level) left a dry, resistant film, while the softest sample (D40, high level) was sticky and difficult to remove.
This reinforces the idea of a “buffable hardness window”, where the cured wax is firm enough to break cleanly but not so soft that it gums, or so hard that it resists wiping.
Dry Time vs. Buffing Ease
Longer dry times didn’t lead to easier buffing. In fact, many samples that dried slowly became more difficult to remove, likely due to additional solvent loss and tighter wax film formation. Buffing performance seemed to peak when haze time was moderate — around 5–6 minutes.
This supports what many professionals observe in practice: there’s an optimal moment to buff, and missing that window — even by a minute — can shift the user experience dramatically.
Application Ease vs. Dry Time
There was no strong correlation between how easily a wax spread and how long it took to haze. Some fast-drying samples spread well; others didn’t. This is expected — application feel is dominated by surface slip and initial wetting, which depend more on viscosity and surface tension than on evaporation rate alone.
Addition Level vs. Buffing Performance
Across most solvents, higher addition levels didn’t consistently improve or worsen buffing. In some cases, they promoted smoother application (e.g. Heptane, D-Limonene), but in others they introduced instability — like weeping in D40 or non-uniform texture in Cyclomethicone. This indicates that each solvent has a compatibility threshold beyond which it disrupts the balance of the wax system.
General Observations During Testing
In addition to the recorded metrics, several qualitative patterns emerged during the hands-on application and evaluation of each sample. These observations provide important context for interpreting the data and offer clues about real-world usability that wouldn’t be obvious from numbers alone.
Visual Appearance and Film Formation
Most samples produced smooth, uniform films when applied to test panels, but two exceptions stood out:
- Sample D (Cyclomethicone, high) showed mild surface non-uniformity. This may indicate partial phase separation or incomplete mixing due to the low surface tension of volatile silicones.
- Sample I (D40, high) exhibited visible liquid weeping after cooling, suggesting poor solvent retention or oversaturation of the wax matrix. This was also the softest and stickiest sample, reinforcing the idea that compatibility matters more than volatility alone.
These findings highlight the importance of visual inspection as part of the evaluation process. Surface inconsistencies, gloss dulling, and oil separation can all signal deeper formulation issues.
Tactile Feedback
Although we measured hardness numerically, the feel during application and buffing offered additional insights:
- Soft samples like D40 (high) tended to smear and resist removal, even though they appeared dry to the touch.
- Harder samples (e.g. D-Limonene, low) felt dry but lacked the mechanical breakaway that makes a wax satisfying to buff.
This again supports the idea of an optimal hardness range — not just for gloss or residue, but for user interaction.
Spread and Over-application Risk
Several solvents — especially Heptane and Isopar M — produced waxes that spread very freely. While this improved coverage, it also introduced the risk of over-application, especially for inexperienced users. In contrast, samples with slightly firmer consistency felt more controlled during use, even if they required a bit more effort to apply.
This is worth considering in training environments and for DIY-focused products where consistency and predictability may outweigh absolute ease of spread.
What This Tells Us About Solvent Selection
One of the key takeaways from this study is that solvent behaviour is formulation-specific. It’s tempting to think of solvents as interchangeable or to select them based on boiling point alone, but our results show that performance is governed by more than volatility.
1. Boiling Point Is Not a Proxy for Drying Time
We saw clearly that lower-boiling solvents like heptane didn’t dry faster, and that higher-boiling ones like D60 and Isopar M often dried more quickly and more cleanly. This suggests that diffusion rate, wax-solvent miscibility, and film formation kinetics are more important than pure evaporation rate. A solvent that flashes too fast may leave wax poorly levelled; one that stays too long may interfere with hardening.
2. Compatibility Thresholds Are Real
At high addition levels, some solvents (notably D40 and cyclomethicone) caused destabilisation — visible as weeping, uneven films, or excessive softening. Others (like Isopar M and D60) were much more forgiving across both levels. This reflects the need to consider a solvent’s chemical behaviour, not just physical properties. Solvents with high surface activity or partial polarity may need structural stabilisation, especially when added in larger volumes.
3. There’s an Optimal “Feel” Zone
Hardness, dry time, and buffing ease don’t exist in isolation — they cluster in a sweet spot that defines a usable wax. Based on this test set, samples with:
- Hardness between 4.5–5.5
- Dry time between 4–6 minutes
- Buffing scores of 4–5+
delivered the best overall experience. This gives us a target zone for refining formulations in either direction — whether for faster workflow or longer open time.
4. Addition Level Isn’t Linearly Predictive
We didn’t see a clear pattern where more solvent meant better or worse performance across the board. In some cases, it helped application or flow; in others, it undermined the structure. This underlines a broader formulation principle: increasing solvent load doesn’t solve problems — it reshapes them. Testing both high and low additions is essential to finding that balance point.
Next Steps
This round of testing gave us a clearer picture of how solvent selection influences not just drying speed or application, but how a wax behaves as a whole. We’ve seen that even simple substitutions can affect everything from tactile feel to visual stability — and that performance is rarely driven by one property in isolation.
Our immediate priorities are:
1. Hybrid Solvent Blends
Many of the solvents tested show value in specific areas — fast flash, strong solvency, high gloss, or structural stability. The next step is to combine the strengths of two or more:
- Pairing a volatile solvent (e.g. heptane or D-limonene) with a slower carrier (e.g. D60 or Isopar M)
- Balancing flash-off and open time to control haze and buffability
- Testing for phase stability and visual clarity under load
This will let us move from discrete solvent trials to real-world blend scenarios, more closely aligned with commercial formulations.
2. Structural Modifiers
We’ve identified edge cases where certain solvents destabilised the wax matrix. To address this, we’ll begin testing:
- Microcrystalline waxes for improved cohesion
- Hydrophobic polymers for gloss retention and film integrity
- Silicone resins or polyethylene wax where hardness and water resistance need a boost
These trials will explore how to reinforce performance without losing ease of use.
3. Training Material Integration
Finally, this data will feed directly into our training programme. The full results, visual comparisons, and performance trends will be used to:
- Help trainees understand how to interpret solvent properties in context
- Reinforce the importance of solvent–wax compatibility
- Offer real data to support learning around formulation trade-offs
As always, the goal isn’t just to find what works — it’s to understand why it works. That understanding is what allows us to make better, faster decisions when designing products or troubleshooting in the lab.
Stay tuned as we build on these results in the next development phase.