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Elastosil RT 623 or RT 623 KR? Same product number, completely different working speed

RT 623 or RT 623 KR? Although the name sounds similar, the differences in real production use are significant. The KR version was designed for fast cycles and mass production, while the standard RT 623 offers greater process control and working comfort for more complex molds. Find out which variant better suits your technology and learn how to choose the right silicone for real production conditions.

Elastosil RT 623 or RT 623 KR? Same product number, completely different working speed

RT 623 or RT 623 KR? Same product number, completely different working speed – which one should you choose for pad printing pad production?

At first glance, the name suggests only a minor difference. The same product number, the same manufacturer, similar applications. In practice, however, ELASTOSIL® RT 623 A/B and RT 623 A/B KR were designed for two different production workflows. Understanding this difference not only helps improve pad quality, but also allows you to significantly shorten production cycles and increase line efficiency.

Same foundation: stability and mechanical durability

Both the standard RT 623 and the KR version are based on the same material concept: they are addition-cured RTV-2 silicones with very good flowability, high mechanical strength, and zero chemical shrinkage. Both materials form a medium-hardness elastomer (around 31 Shore A) with high tear strength and excellent elasticity, which directly translates into long service life of pad printing pads.

In both cases, the user gets a material that maintains hardness stability over time, does not degrade under cyclic loads, and ensures consistent print quality.

Where does the difference begin? Reaction speed

The key difference between RT 623 and RT 623 KR lies in system reactivity.

The RT 623 KR version (KR = “kurzreaktiv”, fast-reacting) was developed for accelerated production processes. The material is characterized by:

  • higher reactivity,

  • faster transition to a tack-free state,

  • shorter demolding time,

  • the possibility of further accelerating curing by heating.

As a result, RT 623 KR significantly reduces the production cycle time for pad molding, which is crucial in industrial environments.

The standard RT 623 A/B offers a more “relaxed” working profile. It gives the operator more time for pouring, degassing, and process adjustments, which is especially beneficial for:

  • larger molds,

  • complex geometries,

  • single-unit or small-batch production,

  • manual pad preparation.

KR = serial production and automation

RT 623 KR perfectly meets the needs of companies producing pad printing pads in serial or semi-automated processes. Fast crosslinking enables:

  • increased mold throughput,

  • better machine utilization,

  • reduced production downtime,

  • faster transition to the next production cycle.

In practice, this means real time and operational cost savings while maintaining the same mechanical quality of the finished product.

Standard RT 623 = greater process control

The classic RT 623 remains an excellent choice where process control is more important than maximum speed. The longer pot life makes it easier to:

  • pour molds precisely,

  • perform manual degassing,

  • work with larger silicone volumes,

  • carry out prototype and test production.

For many users, this “process stability” is more valuable than saving a few hours of curing time.

Mechanical properties: minimal differences

After curing, both materials offer very similar properties:

  • hardness around 31 Shore A,

  • very high tear strength (>30 N/mm),

  • elongation at break up to 700%,

  • high resistance to material fatigue.

This means that choosing between RT 623 and RT 623 KR is not a quality compromise — it is a production strategy choice.

Summary: which one should you choose?

If your goal is maximum efficiency, fast production cycles, and serial manufacturing, RT 623 KR is the natural choice. If, on the other hand, you value greater process flexibility, longer working time, and precise control during pouring, the standard RT 623 remains a very solid solution.

In practice, many companies use both variants in parallel — selecting the material not according to a catalog, but according to real production conditions.