Marking materials include inks, coatings, laser marking materials, tapes, and other supplies used to identify industrial parts, products, materials and packaging. Marking materials are available in many different forms and are designed for specific types of substrates. Some products are dispensed as aerosols, liquids, powders, pastes, solids or transfer tapes. Others are packaged as cartridges, crayons, pencils, films, or laminates. Depending on their form, marking materials can be applied with a brush, copier, roller, printer, or screen. Application methods also include curtain, dip, immersion, electrostatic, spin, and spray coating. Marking materials for metal, plastic, composite, and wood substrates are commonly available. Suppliers may designate products as suitable for aluminum, anodized surfaces, asphalt, ceramics, porcelain, crystals, fabric, fiber, fiberglass, food products, glass, graphite, paper, paperboard, rubber, silicon, or steel. 

Types and Components

Marking materials differ in terms chemistry and color. Inorganic chemistries often contain silicates, cements, or glazes. Ceramic compounds consist of oxides, carbides, nitrides, carbon and other non-metals with high melting points. Resin bases and polymer binders are natural or synthetic, translucent or transparent, and solid or semi-solid. Examples include acrylic, alkyd, copal ester, epoxy, polyurethane, polyvinyl chloride (PVC), and silicone chemistries. Solvent, oil, and water-based marking materials are also commonly available. Wax coatings repel water and are suitable for use with corrugated paper boxes or cardboard. Metallic marking materials are filled with metals such as aluminum, copper, zinc, or stainless steel. In terms of color, choices for marking materials include: black, blue, brown, gray, green, orange, purple, red, white, yellow, clear, and transparent. 

How to Select

Selecting marking materials requires an analysis of processing parameters and performance specifications. Processing parameters include coverage, wet thickness, dry thickness, cure or dry temperature, cure or dry time, viscosity, specific gravity, humidity, and particle size. Pot life and VOC content are also important considerations. Pot-life is the time between the mixing stage and the gel stage at which a marking material remains usable at 77^o F. Pot life for epoxies depends on variables such as temperature, the shape of the container, and the hardener used. Volatile organic compound (VOC) content is regulated by state, federal, and provincial governments. Performance specifications for marking materials include conductivity, resistivity, dielectric strength, index of refraction, and transmission. 

Features and Applications

Suppliers of marking materials describe products in terms of features and applications. Some marking materials are abrasion resistant, chemically resistant, conductive, dielectric, glow-in-the dark (photoluminescent), heat resistant, impact resistant, or designed for high-temperature applications. Others are temperature indicating, VOC compliant, waterproof, weatherproof, water repellant, wear resistant, or reflective. UV resistant marking materials protect against damage from ultraviolet (UV) radiation. General-purpose products are designated for interior or exterior use. In terms of applications, marking materials are used in a variety of market segments, including: aerospace, agriculture, automotive, commercial, chemical processing, material processing, mining, military, pharmaceutical, food processing, semiconductor, and security.

Standards

ASTM D4796 - Standard Test Method for Bond Strength of Thermoplastic Traffic Marking Materials

BS EN 61249-8-7 - Materials for Interconnection Structures Part 8: Sectional Specification Set for Non-Conductive Films and Coatings Section 7: Marking Legend Inks

BS EN 13212 - Road marking materials - Requirements for factory production control

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