Purple-to-Blue Color Changing Thermochromic Pigment, 31°C – KTP-30-VB

Purple-to-Blue Color Changing Thermochromic Pigment, 31°C – KTP-30-VB

Special Effect Pigments › Thermochromic Pigment Series › Colored-to-Colored (C2C)

KTP-30-VB is a Purple-to-Blue thermochromic pigment with a 31°C activation temperature in the fine 3–10μm particle size range — a Colored-to-Colored (C2C) microencapsulated leuco dye pigment that transitions from purple below 31°C to blue above 31°C in response to body temperature or warm contact. The shift between two cool-family colors produces a perceptible but tonally coherent color change — the product reads as purple when cool and blue when warm, with both states remaining visibly colored on any substrate without requiring a reveal-layer base coat design. At 3–10μm, KTP-30-VB is processable in printing inks, nail lacquer, coatings, and cosmetic systems without surface texture in cured films.

Purple-to-Blue — Design Character of an Adjacent Cool-Hue Shift

Purple and blue are adjacent on the color wheel — they share the cool color family but are clearly distinct to the eye. The purple-to-blue transition reads as a temperature-responsive modulation within a consistent cool-tone aesthetic rather than a dramatic contrast shift. In nail lacquer and cosmetics, this color behavior suits product positioning where temperature-responsive color is a feature of the overall cool-tone design language — purples and blues are frequently used in night-tone, celestial, and ocean-themed ranges where a shift between these adjacent hues reinforces rather than disrupts the product identity.

For applications requiring maximum visual contrast at the transition point, high-contrast pairs like KTP-30-BR (Black-to-Red) or KTP-30-GY (Green-to-Yellow) are more appropriate. KTP-30-VB is the correct specification when the design brief calls for a cool-family color shift that feels natural and thematically coherent with blue-violet cosmetic or decorative positioning.

Technical Specifications

Kolortek C2C Series — Full 31°C Color Shift Range

All C2C grades activate at approximately 31°C (3–10μm). Colored-to-Colorless (C2CL) grades at 31°C and other temperatures available in the KTP-31 and KTP-16/17/18/22/32/43/45 series. BPA Free food-grade C2CL grades available — see KTP-31-RBF, KTP-31-GBF, and others.

Technical Characteristics

Cool-family shift — substrate independence advantage: KTP-30-VB maintains a visible color in both temperature states — purple below 31°C, blue above 31°C. Both are clearly colored and visible on white, light, and dark substrates without needing a base coat to provide warm-state visual content. Colored-to-Colorless grades at 31°C (e.g., KTP-31-VP Purple) require a pre-designed base coat to produce a meaningful result when the pigment becomes transparent. For formulation simplicity — particularly in nail lacquer where base coat choice affects final appearance — the C2C format eliminates one design variable.

Body-temperature activation in wear conditions: At 31°C, KTP-30-VB activates during normal skin contact and product wear. In nail lacquer, hands warm above 31°C during typical activity — the shift to blue occurs and persists. When hands cool, such as with cold water or cool air exposure, the reverse to purple begins. The transition is not instantaneous; it progresses across the activation range (approximately 28–34°C in practice) producing an intermediate mixed tone visible briefly during the transition. This intermediate visual is a characteristic of all thermochromic pigments, not specific to KTP-30-VB.

Combining with C2CL blue or violet grades for layered effects: Adding a static blue or violet pearlescent (e.g., KT-225 Blue Pearl or KT-219 Violet Pearl from the KT-200 series) alongside KTP-30-VB creates a formulation where the background shimmer remains constant while the thermochromic layer shifts the foreground color. The total perceived color in the cold state is purple-tinted by both the pigment and the static component; in the warm state the thermochromic shifts to blue, aligned with the static blue pearlescent. This layered approach reduces the visual transition at very low loading levels by providing a consistent color anchor.

Processing — low-shear is the absolute constraint: The microencapsulated leuco dye system in KTP-30-VB requires complete protection from mechanical shear throughout the formulation process. Add KTP-30-VB at the final mixing stage after all dispersing, milling, and high-shear steps are finished. Use only low-shear paddle or anchor mixing for incorporation. Any capsule rupture is permanent — the affected particles become static purple or blue pigment with no thermochromic recovery. Kolortek has maintained consistent activation temperature calibration and capsule integrity specifications across thermochromic production for over 20 years. TDS and SDS on request.

Application Range

Frequently Asked Questions

Q: How does KTP-30-VB (C2C Purple-to-Blue) compare to KTP-31-VP (C2CL Purple, Colored-to-Colorless) for nail lacquer?
A: KTP-31-VP is purple when cold and becomes colorless when warm — the warm-state visual depends entirely on the base coat beneath. If you apply KTP-31-VP over a clear base, the warm nail appears clear/colorless. If over a blue base coat, the warm nail appears blue. The design flexibility is high but requires deliberate base coat planning. KTP-30-VB shifts from purple to blue with no base coat dependency — the blue warm state is intrinsic to the pigment. Choose KTP-31-VP when you want to control the warm-state color through base coat selection; choose KTP-30-VB when you want the purple-to-blue shift without managing a reveal layer system.

Q: Will the purple-to-blue shift be visible in both cool and warm room temperatures, or only on direct skin contact?
A: At typical room temperature (20–25°C), KTP-30-VB remains in the purple state — the 31°C threshold is above ambient indoor temperature. The shift to blue requires bringing the pigment to approximately 31°C or above, which occurs during skin contact (body temperature typically 32–37°C on skin surface), in warm environments (hot weather, proximity to heat sources), or on warm substrates. In a cool room, a product formulated with KTP-30-VB will appear purple. Upon contact with warm hands or skin, the blue shift activates. This makes the activation behavior touch-dependent under typical indoor conditions.

Q: Can KTP-30-VB be mixed with KTP-30-GB (Grey-to-Blue) to create a multi-layer cool-family thermochromic effect?
A: Yes — C2C grades from the same activation temperature can be combined in a single formulation or applied in separate layers. Blending KTP-30-VB and KTP-30-GB produces a combined formulation where the cold state is a mixed purple-grey and the warm state is blue from both components simultaneously. Applying them in separate printed layers allows independent control over how much of each contributes to the final visual. In either approach, the total thermochromic loading level affects both transition clarity and color saturation — bench evaluation of blend ratios under your specific film thickness is essential before finalizing the formulation.

Request Samples or Technical Documentation

The purple-to-blue shift of KTP-30-VB is best assessed in your specific formulation system and under your product lighting conditions. Contact Kolortek to request samples of KTP-30-VB alongside other C2C and C2CL grades for direct comparison, download the TDS, or discuss formulation guidance for nail, cosmetic, or printing ink applications.