Silicone Product Hardness Selection Tips


silicone rubber is an elastomer that has many unique properties that enable the extensive use of silicone rubber for different applications in the medical, food, aerospace, and consumer industries.

What are the different types of silicone?

* FSR-Fluoro silicone Rubber

* HCR-High Consistency Rubber (or solid silicone rubber)

* LSR-Liquid Silicone Rubber

* RTV-Room temperature Vulcanize



Like silicone, fluoro silicone rubber is a long-lasting elastomer that is stable, typical applications include aerospace fuel system components, diaphragms, gaskets, hose lining, seals, and O-rings.


Based on the different cure and processing methods, silicone rubber can be classified as solid silicone (HCR) and liquid silicone (LSR).

HCR is produced as gummy, high viscosity solid rubber that is partially vulcanized. Process ways include compression molding, transfer molding, and extrusion of rubber tubing.

LSR on the other hand are supplied in drum or pails in liquid rubber form, due to their low viscosity, injection molding is the perfect way to process LSR.

HCRs are less expensive than LSRs both for raw material and tool mold cost. HCR’s methods are better suited for smaller production runs, while LSR is a better fit when making thousands or millions of parts.



In terms of polymer employed and the curing process, silicone rubbers can be divided into room temperature vulcanized rubbers(RTV) and high-temperature vulcanized rubbers(HTV). RTV silicone rubbers come as a soft paste or a viscous liquid. HTV silicone rubbers come in two different physical states: liquid and solid.

The above are various types of silicone rubber, in this post, we will focus specifically on the HCR silicone rubbers’ special properties and their applications.


Silicone materials classification,characteristics and applications

Silicone rubbers have exhibited excellent properties, such as thermal conductivity, fire resistance, good chemical stability, flame retardancy, excellent resistance to heat and cold, etc. By changing the base polymer, adding reinforcing filler and special additives, parts of properties will be strengthened significantly to meet special application needs, silicone rubber will be classified based on its standout properties.


General Purpose silicone rubber


  1. General-purpose siliconerubber

General-purpose silicone rubber has the basic feature of silicone, heat resistance, flame retardance, chemical stability, UV resistance, etc, it can be used to fabricate any commonly used silicone products such as kitchenware. Generally, if products have no special application need, general-purpose silicone material will be used. The normal hardness range from Shore A 30 ~70 in cure state.

  1. Low hardness siliconerubber

This kind of silicone has very low hardness Shore A 5~20.

Feature: high strength, low hardness, high elongation, very soft

Application: baby nipple, fresh-keeping film, anti-slip mats, shoes insole, silicone molds.


                               silicone paciflier                                                                              thermosets


3.High hardness siliconerubber

Material hardness up to Shore A 90 after curing.

Feature: high hardness and rigidity, high dimensional stability

Application: an alternative to thermoplastic or thermosets


  1. High tear strength silicone

The tear strength of general silicone is about 9.8 kN/m, high strength silicone can be 29~49 kN/m, ideal for molding items that require high tear strength.

Feature: excellent tear resistance, high tensile strength, high elongation

Application: silicone stretch & seal lids, silicone bands, remote control cover.



  1. High transparency silicone

This kind of silicone are highly transparent with good strength.

Feature: super transparency, high tear strength, easy to color with color pigments.

Application: medical tubing, silicone nipples, silicone cases

  1. Flame retardant silicone

Silicones are flammable, they can be burned into white ash, however by adding a small amount of flame retardant, silicone can comply with UL94 V-0, V-1, or V-2 standards.

Feature: flame retardant, no poisonous gases released

Application: consumer electronics, subways, wires and cables, electricity meters



          silicone medical tubing                                                    Flame retardant silicone


  1. Thermal conductive silicone

They are designed with high thermal conductivity and heat resistance.

Feature: High thermal conductivity, electrical insulation, heat resistance

Application: thermal conductive gasket, heat transfer pads, computer CPU, power supplies


  1. Electrically conductive siliconerubber

They are silicones filled with electrically conductive material carbon black.

Feature: electronic conductivity, low amperage conductor, thermal conductivity

Application: keypads, cable connectors, gaskets, washers.


 Thermal conductive silicone                                                           heat resistant cots


  1. High heat resistance silicone rubber

They are designed for use in challenging environments with temperatures up to 250 ~ 300°C in a certain period.

Feature: high temperature capability

Application: heat resistant cots and seals, auto parts,silicone spatula

  1. Oil-resistant siliconerubber

They are specially made silicone with better oil resistance at a higher temperature.

Feature: excellent oil resistance

Application: gasket applications, O-rings, and seals



From the above we can see silicone materials are formulated into so many different types, so choosing the best fit material is crucial to your project’s success, please inform us in advance of your specific application needs so we can recommend the right material for your cases.

About XHF Silicone :

18+ years of experience in CNC mold making and custom molded silicone products;

R&D Support (Custom products design, 3D files)

CNC tool mold design and process (Programming, mold making)

Silicone Molding Production (High Volume Production, Quality Control)


Customers who want to develop custom silicone products are welcome to contact us at :

[email protected]


Dongguan XinHongFa Silicone Manufacturing Co., LTD.

Custom-made various types of silicone kitchenware, baking tools,products,etc

If you have requirements for silicone materials, we can also meet your needs!  WELCOME to INQUIRE!