ST Series ink

ST Series Standard white vs Competition extra white
ST 310 White ink
ink for apparel tags and rubber applications
custom apparel label printing
ST Series on rubber like substrates
ST Series inks for EPDM Rubber
Screen printing ink for YET bags
ST Series ink for pad printing on basket balls

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ST Series Pad Printing Ink

Screen Printing Inks, Pad Printing Inks


ST pad printing ink is an easy-to-print, ultra-fast-drying, high-opacity, 1- or 2-component pad printing ink for soft touch materials, rubber, apparel, and natural and synthetic fibers. This ink is durable and flexbile. It can also withstand many industrial washing cycles. As a result, it is the best ink for t-shirt care label printing, shoes, industrial rubber marking, and rubberized soft-touch promotional products. Typical applications include Printing on Stress Balls, Sporting Goods, Skateboard Wheels, Soft Touch Surfaces, Soft PVC, ID Cards, Binders/Report Covers, and Textiles.

Also, with the hardener added, the ST Series ink film is much more resistant to mechanical wear. Even after hundreds of washings, this printing ink will not fade because we only use pigments with high fade resistance. The pot life of the ink-hardener-solvent mixture is 6–8 hours at room temperature (70°F and 40–65% RH). After adding the i-300x pad printing hardener, the ink-hardener mixture becomes chemically reactive and must be processed within 6–8 hours. Please see TDS for additional information.

Like all other Natron printing inks, the ST series is classified as non-toxic (NT)—the pigments are free from heavy metals. For more information, please see our safety data sheets, which are available in accordance with EU and US regulations. Additionally, the product label has the primary indications displayed.

The Natron ST pad printing ink is also available in six neon (fluorescent) colors, four metallic colors, and 23 high-opacity standard colors. All colors in this ink series are inter-mixable.

  • Highly flexible ink film for maximum wear comfort
  • Very good resistance to industrial washing
  • High opacity makes it ideal for printing on dark substrates.

Available Sizes

  • 1.0Kg (2.2lbs)


  • i-300X


  • TMF (Fast)
  • STB
  • TDG

Have questions about pad printing ink?

Technical Specs

Available Colors








Lemon Yellow




Gold Yellow






Rose Red






Kelly Green




Bright Green




Process Blue




Reflex Blue


Ultramarine Blue


Dark Blue






Cool Gray 9


Cool Gray 6


Rich Gold






Neon Yellow


Neon Red


Neon Pink


Neon Green


Neon Blue


Neon Orange

Very High Opacity

The Natron ST series is intended for pad printing on rubber, natural, and synthetic fabrics that require high opacity, fade-resistant inks, which this ink provides. This ink series ink film has very high opacity.

Very good wash and mechanical resistance

This ink series is resistant to industrial machine washing. Washing resistance is achieved after a full cure of 24–48 hours at 20 °C (70 °F). The ST series is able to withstand over 50 industrial washes.

Very flexible

Outstanding flexibility and elasticity are two of the major characteristics of the ST ink line. As a result, this is the perfect ink for printing on flexible rubber substrates such as EVA, EPDM, and many other rubber substrates.

Abrasion resistance

For non-textile substrates such as EPDM, EVA, and soft-touch coated surfaces, the ST Series ink film exhibits outstanding adhesion, resulting in excellent rub, scratch, and block resistance. This pad printing ink is resistant to chemical products such as oils, greases, and solvents.

Durable, supercharged inks!

Print on Textiles, rubber, and soft touch substrates!

ST Series Mixing and Printing instructions

The only way to mix printing ink is by weight, whether you’re adding hardeners, solvents, or mixing different colors to make a new color.

  • To use the ink as one component, add the solvent to the ink. Mixing ratio: 10–35% of the ink’s weight, depending on the color. Solvent is added to the ink to adjust the ink’s viscosity. The choice of solvent and the amount added are highly dependent on the printing environment and the printing speed.

Using the ink as a two component ink

  • A two component ink has two components; the solvent and the hardener. This ink uses the i-300X hardener. Two component inks have a pot life of 8 hours.
  • Pour the printing ink into a mixing container and note the weight.
  • Add the hardener to the ink. The mixing ratio is 10 parts ink to 1 part hardener, i.e., 10% of the ink’s weight. Mix the ink and the hardener together.
  • The solvent, which should be between 10% and 35% of the ink’s weight, should then be added to the ink-hardener mixture.

Note, the ink-hardener-solvent mixture is chemically reactive and must be processed within 7–9 hours.

Printing Parameters: Pad Printing

  • Printing Plates (clichés) – Textiles
    Use any commercially available clichés that are made of ceramic, photopolymer, laser, or steel plates. The recommended cliché depth is 35 μm for standard prints and 50μm for half tones.
  • Printing Plates (clichés) – Hard goods/ rubber substrates
    Use any commercially available clichés that are made of ceramic, photopolymer, laser, or steel plates. The recommended cliché depth is 20 μm for standard prints and 35μm for half tones.
  • Printing pads
    Use silicone printing pads. The ink works regardless of the hardness (durometer) of the pad. 60 – 65 Durometer for textiles.
  • Printing machines
    The Natron ST Series is suitable for both closed-cup and open-ink well machines. Use the appropriate thinner for the correct type of machine. For open ink wells, use slower pad printing ink solvents (thinners).

Printing Parameters: Screen printing

For screen printing, use any of the commonly available polyester meshes and solvent-resistant emulsions. Use 110–156 mesh (mesh per inch)-count screens for the highest opacity and on dark substrates. Use a mesh count of 230 for fine details.

ST Series and the Environment

The ST Series pad printing ink is non-toxic ink that is made with pigments that don’t fade and don’t contain any heavy metals. Additionally, it is eco-sustainable, meaning that it does not contain:

  • Alogens
  • Azo dyes
  • Formaldehyde
  • Latex
  • PAH
  • Phthalates
  • Animal origin ingredients
  • Bisphenol A (BPA)
  • G-B ester
  • Melamine
  • Persistent organic pollutants

Frequently Asked Questions

Yes. We recommend adding at least 10% – 15% of inks weight into the ink.

Adding the i-300X hardener allows the printed tags to pass over 50 industrial wash cycles. Without the hardener, the printed labels will start to fade after 15 industrial wash cycles.

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