Ambient Temperature in Handmade Watercolor Systems: Long-Term Material Observations

In records of handmade watercolor systems, ambient temperature serves as an ongoing independent variable. Unlike seasonal shifts, which usually alter temperature and humidity simultaneously, temperature can be isolated and observed as a single factor. Material responses vary significantly across different processing stages, and different pigments and binder systems show varying degrees of sensitivity. Therefore, no single uniform pattern applies to all colors.

1. Temperature Responses During Making and Natural Drying

During the mixing and drying phases, ambient temperature directly influences the rate of moisture evaporation, affecting how the paint sets into its final form.

• Drying speed differences at high room temperatures: When ambient temperatures are high, the natural drying speed of certain color combinations accelerates noticeably. A solid layer may form quickly on the surface while the interior still retains high moisture. This timing gap between surface drying and core drying leads to internal cavities in specific colors.
• Differences in stability across color systems: High temperatures do not automatically cause internal cavities in all colors. Some color combinations maintain a stable form in warm room air, while others show higher sensitivity. These differences depend on pigment properties, particle shapes, and binder formulation. The accurate observation is that high room temperatures increase the likelihood of rapid surface hardening and uneven drying in certain specific colors.

2. Distinguishing Between Liquid and Solid States

The impact of temperature depends heavily on the physical state of the paint (whether liquid or already hardened) and requires separate observation for each stage.

• High-temperature responses in the liquid state: Paints still in a liquid or incompletely hardened state can undergo noticeable changes in shape and volume under elevated ambient temperatures. Certain colors exhibit material expansion, internal gas pressure, and the formation of numerous bubbles and net-like foam structures. This represents a specific behavior of liquid materials under thermal exposure.
• Extreme tests under very high temperatures: In extreme tests involving artificial heating (such as specific high-heat environments), paints in the formation stage display intense outward expansion, bursting, and large internal gaps. These extreme tests serve strictly to observe boundary limits and differ fundamentally from natural drying under normal making conditions.

3. Temperature Impacts in the Hardened State and During Storage

After complete natural drying and transition into a solid form, changes in ambient temperature trigger different visual responses than those seen in the liquid phase.

• Solid-state responses to warmth (cracking and softening): At higher storage temperatures, surface cracking appears on some hardened colors. The extent of cracking varies depending on the pigment and binder system: some colors show distinct changes, while others show minor or no changes. Additionally, rising temperatures can cause certain solid colors to soften, indicating that the surface structure remains changeable with temperature even after hardening.
• Surface conditions at very low temperatures: When paints are exposed to very low temperatures (such as freezing conditions), the paint body itself usually does not freeze completely. However, ice crystals and moisture readily form on the surface. For solid paints, repeated cycles of moisture and ice formation disrupt the surface appearance, making extremely low temperatures unsuitable for long-term storage of standard solid watercolors.

4. Specific Applications of Temperature and Observation Boundaries

The relationship between temperature and material stability is not purely linear. Low temperatures can offer practical material value under specific conditions.

• Specific requirements for cool storage: Although extremely low temperatures are unsuitable for regular solid paints, maintaining long-term stability at normal room temperature is difficult for certain binder systems or specific color mixtures. Under these specific conditions, keeping a consistently cool environment is necessary to extend the material's shape stability over time.
• Summary and storage range: Observation records demonstrate that temperature acts on an interconnected system of pigment, binder, moisture content, and processing stage. For routine making and storage, maintaining a stable environment at or slightly below room temperature is most effective for preserving the shape stability of handmade watercolors.

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