Handmade Watercolor Systems: Long-Term Material Observations on Environmental Humidity

In long-term records of handmade watercolor systems, environmental humidity is a continuous baseline variable. Unlike temperature, humidity is often not directly felt, yet it remains present throughout all seasons and affects various stages—from preparation, natural drying, and hardening to long-term storage and practical use.

Long-term observations show that humidity does not affect all colorants in the same way. Responses vary significantly depending on the binder system and pigment combination. Therefore, humidity cannot be treated as a uniform standard parameter for all colors.

1. Material Behavior During Natural Drying

After handmade watercolors are mixed, they gradually release moisture under natural ambient conditions until reaching a relatively stable solid state. The level of environmental humidity directly changes how moisture moves from inside the paint into the surrounding air.

• Slower drying in high humidity: In higher humidity, the air's capacity to hold moisture changes, noticeably slowing down the overall drying process. For color mixtures that naturally dry slowly, high humidity can significantly extend their formation period. Under these conditions, while a solid outer layer may gradually form on the surface, the core requires much more time to reach a stable state. Certain pigment-and-binder combinations tend to remain soft or easily reactivated over extended periods.
• Drying speed differences in low humidity: In very dry environments, moisture on the paint surface evaporates faster, forming a solid outer shell quickly. However, because internal moisture must still move outward, the rapid hardening of the outer layer leads to an uneven drying pace between the surface and the core. In certain colors, this behavior develops into internal cavities.

2. Differences in Sensitivity Across Paint Systems

Records document that the binder system determines the overall environmental sensitivity, while the specific pigment influences how that material response presents itself.

• Honey watercolor systems: Among all tested systems, honey-based watercolors respond most noticeably to humidity changes. Colors using this binder system are more susceptible to ambient humidity shifts. However, individual pigments retain their own properties, meaning not every color experiences identical changes.
• Metallic and chameleon watercolor systems: In comparison, metallic and chameleon watercolors show lower sensitivity to humidity. High humidity slightly slows their drying, while low humidity slightly accelerates it. In long-term records, these systems did not exhibit widespread internal cavities related to humidity shifts that would require adjustments; overall material stability remained consistent.

3. Ongoing Effects on Hardening and Storage Microclimates

The impact of humidity goes beyond the drying timeframe, affecting final hardening levels and long-term storage.

If the storage environment remains continuously humid, certain colors in the honey watercolor system may struggle to reach a fully hardened state, leaving them easily reactivated by moisture over time. If already hardened paints experience a sudden jump in ambient moisture, the surface may soften again or tend to stick.

During regular painting use, the inside of a watercolor palette creates its own microclimate. If left closed in a high-humidity state for a long time, the paint inside may absorb moisture, soften, or re-activate. Under specific conditions, there is also a risk of mold growth. Regarding potential mold, these records note only visually observable external risks in humid conditions; specific microbiology or underlying growth mechanisms are outside the scope of visual material records.

4. Summary and Observation Boundaries

The effect of environmental humidity acts on an interconnected system made of pigment, binder, water content, ambient air, and storage container. Temperature and humidity should be treated as two independent variables: high temperatures can speed up drying, while high humidity slows it down. High temperatures with low humidity encourage rapid surface drying, while low temperatures paired with high humidity lead to very slow formation processes.

Humidity does not alter the fundamental category of the paint; instead, it changes the timeframe and physical appearance of the transition from one state to another. For long-term preservation, maintaining a relatively stable and not overly humid environment helps preserve the solid-state stability of handmade watercolors (especially honey-based systems).

Video recordings documenting parts of the handmade watercolor process and pigment behavior are archived at VHacademy (an independent material behavior research project accessible via paid access).