| Application and Substrate | Specify whether the powder will be used in solvent-based ink, water-based ink, plastic masterbatch, coating, paint, textile printing, packaging, or another formulation. | Define the substrate, binder or polymer, processing method, and expected contact conditions before requesting samples. | Thermochromic powder performance depends strongly on compatibility with the carrier system and processing temperature. | Require a technical data sheet and test the powder in the final formulation rather than in a carrier-free condition. |
| Activation Temperature | Identify the temperature at which the color change must begin and the temperature at which the final color state should be reached. | Common commercial grades are available around 15°C, 25°C, 31°C, 37°C, 45°C, and 60°C, subject to grade availability and tolerance. | The activation point determines whether the product responds correctly to touch, cold-chain exposure, warm beverages, medical indicators, or industrial heat. | Measure color change during controlled heating and cooling cycles using a calibrated temperature probe. |
| Reversible or Irreversible Behavior | State whether the material should return to its original color after cooling or remain permanently changed after exceeding a specified temperature. | Use reversible grades for repeated-use indicators; use irreversible grades for one-time temperature exposure records. | Reversible and irreversible systems serve different applications and cannot be evaluated by the same performance criteria. | Run at least five heating-and-cooling cycles for reversible grades and document the color response after each cycle. |
| Color System | Define the initial color, activated color, background color, opacity, and whether a color-to-color or colored-to-colorless transition is required. | Specify color references using an agreed visual standard or measured color values such as CIELAB, rather than color names alone. | Color names can vary between suppliers, while measured values provide a more consistent basis for approval and batch comparison. | Compare approved samples under standardized lighting and record color difference with a colorimeter when required. |
| Particle Size and Dispersion | Set the required particle-size distribution and dispersion behavior for the printing, coating, or compounding process. | A typical requirement is a fine powder suitable for the selected screen, nozzle, film thickness, or polymer process; the exact limit must be validated in the application. | Large agglomerates may cause clogged screens, rough surfaces, visible specks, poor color uniformity, or unstable dosing. | Request particle-size data, inspect dispersion by microscopy, and conduct a production-equipment trial. |
| Thermal Processing Limit | Define the maximum temperature and residence time the powder will experience during drying, curing, extrusion, molding, or lamination. | Select a grade whose processing window remains below its documented degradation or performance-loss threshold; avoid assuming that activation temperature equals processing temperature. | Excessive heat can permanently damage the color system, reduce sensitivity, or shift the activation temperature. | Request thermal-stability data and compare color strength before and after the intended process cycle. |
| Light and Environmental Resistance | Define expected exposure to sunlight, UV radiation, humidity, water, chemicals, abrasion, and storage temperature. | Set a required service life and test duration according to the end use; indoor and outdoor products should not use the same durability assumptions. | Many thermochromic systems are more sensitive to prolonged UV exposure and harsh chemicals than conventional pigments. | Conduct application-specific accelerated light, humidity, chemical, and abrasion tests using agreed acceptance criteria. |
| Concentration and Formulation Compatibility | Specify the required loading level, viscosity range, binder type, solvent or water system, pH, and mixing energy. | Establish a laboratory dosage series first, for example low, medium, and high loading levels, then select the lowest level that meets color and coverage requirements. | Higher loading does not always improve performance and may affect viscosity, adhesion, flexibility, opacity, or cost. | Evaluate dispersion stability, color strength, settling, adhesion, and final-film appearance after storage. |
| Regulatory and Product Safety Documentation | Identify the destination markets and the product-contact requirements, including packaging, toys, textiles, cosmetics, or other regulated uses. | Request a current SDS, technical data sheet, composition or restricted-substance statement, and market-specific compliance declarations where applicable. | Regulatory obligations vary by application and destination. Documentation should be reviewed for the finished article, not only the raw powder. | Use an independent laboratory or qualified regulatory reviewer when the application involves food contact, toys, skin contact, or children’s products. |
| Quality-Control Specification | Define measurable release criteria for appearance, color strength, activation temperature, moisture, particle size, and batch consistency. | Create a written specification with approved reference samples, test methods, sampling plans, and tolerance limits before mass production. | A clear specification reduces disputes and makes suppliers in different regions directly comparable. | Require a certificate of analysis for each lot and retain control samples for comparison during incoming inspection. |
| Packaging and Storage | Specify protection from moisture, heat, light, contamination, and mechanical damage during international transport and warehousing. | Use sealed, moisture-resistant inner packaging with clear lot identification; store in a cool, dry, dark location according to the supplier’s instructions. | Improper storage can reduce shelf life and cause performance variation before the powder reaches production. | Review packaging specifications, storage conditions, production date, recommended shelf life, and transport records. |
| Shelf Life and Batch Traceability | Define the minimum remaining shelf life required at receipt and the traceability information that must accompany each shipment. | Require lot number, manufacturing date, retest or expiry guidance, net weight, and a documented change-notification process. | Thermochromic performance may change during long storage, especially under heat, humidity, or light exposure. | Perform incoming inspection and periodically retest retained samples against the approved reference lot. |
| Supply Continuity | Assess production capacity, lead time, geographic risk, backup manufacturing capability, and availability of critical raw materials. | Qualify at least two technically acceptable supply routes when business continuity is important, while recognizing that color matching between sources requires validation. | Changing suppliers can alter color, activation temperature, particle size, or dispersion behavior even when the product description appears identical. | Conduct second-source qualification and require advance notification of formulation, process, or raw-material changes. |
| Commercial Evaluation | Compare total landed cost rather than powder price alone, including sampling, testing, packaging, freight, duties, insurance, and rejected-batch risk. | Evaluate suppliers using the same specification, sample quantity, delivery term, payment condition, and quality requirements. | A lower unit price may be offset by higher freight, additional testing, inconsistent batches, or poor compatibility with the final process. | Use a weighted sourcing score covering technical fit, compliance, quality, delivery reliability, and total landed cost. |
| Pre-Approval Sample Plan | Define the number of samples, test batches, accelerated-aging tests, and production trials required before approval. | Approve only after laboratory evaluation, pilot-scale processing, packaging or substrate testing, and a documented comparison with the reference sample. | Small laboratory tests may not reveal shear, drying, extrusion, coating-thickness, or scale-up problems. | Record formulation, equipment, processing temperature, test conditions, results, deviations, and final approval status. |
