HT 45 addition-cure silicone

HT 45 Transparent Zhermack - Silicone Liquid Rubber RTV2 Additive for Technical Matters

Silicone RTV2 with high hardness for moulds, prototypes, ceramics and jewellery

HT 45 Transparent Zhermack RTV2 two-component rubber with vulcanization by addition to ambient temperature. It is intended to make the molds and duplicate models, especially in applications where the precision of reproduction, dimensional stability and a mould with a stronger consistency are important.

The system consists of two components, BASE and CATALYST, which are mixed in the ratio 1:1. After 24 hours, vulcanized silicone has a hardness declared by 43 ± 3 Shore A.

Compared to a softer silicone, this hardness can be useful when the user wants a flexible mould, but with a stronger outfit. The choice of hardness must be made according to the geometry of the piece, the deformation requirement at the demoulding and the process in which the mould will be used.

Recommended applications

According to the technical documentation Zhermack, HT 45 Transparent is recommended for:

• making molds and modeling-making - for applications where reproduction accuracy, dimensional stability and mechanical strength are important;
• rapid prototyping - for the production of the moulds used in prototyping processes;
• artistic ceramics - for the reproduction of models and the production of moulds;
• jewellery - to make the moulds and duplicate the models.

In practice, HT 45 is also chosen by users seeking a more firm mould than the one obtained with the more hardheaded Shore A silicone. This feature may be relevant for certain technical or industrial applications, but the choice must be made according to the concrete geometry of the piece and the process of demoulding.

Practical advantages

• High hardness for a mould silicone - 43 ± 3 Shore A after 24 hours.
• Simple mixing ratio 1: 1 - BASE and CATALYST weigh in equal amounts.
• Good fluidity - the viscosity of the mixture is less than 8000 cP.
• Relatively short curing time - 60-90 minutes at 23 ° C
• High dimensional stability - important for the reproduction of technical models.
• mechanical strength - relevant characteristic for the repeated handling and use of the mould.
• Relapse resistance - declared value of 19 ± 2 N / mm.
• Reproduction of fine details - one of the characteristics mentioned by the manufacturer for this material.

Main technical characteristics

• Type: silicone RTV two-component, with vulcanization by addition
• BASE mixing ratio: CATALYST: 1:1
• Vascosity of the mixture: less than 8000 cP
• Density: 1,1 g / cc
• Working time at 23 ° C: 10-12 minutes
• curing time at 23 ° C: 60-90 minutes
• hard after 24 hours: 43 ± 3 Shore A
• Relapse load: 3,5 ± 0,5 N / mm ²
• Landing at break: 370 ±40%
• Relapse resistance: 19 ± 2 N / mm

Working time and curing time

At temperature of 23°C, working time for HT 45 Transparent is about 10-12 minutes. The curing time is approximately 60-90 minutescalculated from the beginning of mixing the two components.

Environmental temperature directly influences these times. At temperatures above 23 ° C, working time and curing time shall be reduced. At temperatures below 23 ° C, they increase considerably.

For this reason, the model, containers and all necessary materials must be prepared before mixing the components.

Completing a multi-step mould

If the first quantity prepared is not sufficient to complete the mould, the silicone can be allowed to strengthen, and the additional material can be added within 24 hours of the first casting being cured. According to the manufacturer's documentation, the added material adheres to the silicone without altering the final result.

Compatibility and precautions

The technical documentation mentions the compatibility of HT 45 Transparent with gypsum, coatings, polyurethane resins and acrylic resins.

Important: Same documentation requires contacting the manufacturer before the silicone comes into contact with polyurethane resin. For a concrete application with polyurethane resin, we recommend checking compatibility prior to the final mould.

Best TOOLS Recommendations

HT 45 Transparent is an option to consider when the project requires a flexible mould, but with a firmer outfit. The higher hardness can be advantageous for certain technical moulds and industrial processes, but it does not automatically mean that a tougher silicone is more suitable for any geometry.

For models with pronounced retention areas or geometry that require significant deflection of the mould upon demoulding, the necessary hardness should be carefully evaluated.

Complementary products useful for processing HT 45 Transparent:

• precision scale - for dosing the components in ratio 1: 1;
• mixed containers - for controlled preparation of silicone;
• Mixture spatula - for complete mixing of components,
• Vacuum equipment - to degas the mixture,
• Sulphur-free modeling plastic - for the preparation of certain patterns and the construction of the moulds, when the process requires this material.

Common questions about HT 45 Transparent

Conclusion

HT 45 Transparent Zhermack RTV is a two-component silicone of addition designed for the realization of molds and modeling applications, rapid prototyping, artistic ceramics and jewelry. The hardness of 43 ± 3 Shore A allows obtaining a flexible mould with a firm outfit and the curing time of 60-90 minutes at 23 ° C makes it suitable for processes in which precision, dimensional stability and a relatively fast working cycle are important.