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Silicone Rubber Kit (Economy)

Looking to take the first step on your mould making journey? Our Silicone Rubber Kits are the best place to start.

We offer two grades of silicone rubber. Our professional grade, Silicone Rubber 3481 and our economy grade, known as Economy Silicone Rubber.

All our kits come in two parts – a silicone rubber base and a catalyst liquid. When mixed together they combine and start to set.

£12.00 - £290.00

Next Day Delivery*

We endeavour to dispatch all order within 24 hours, but please allow 3-5 working days for delivery (due to current global supply chain issues).

Shipping Information

Our shipping costs are worked out by the gross weight of your order delivered to your address. NB: We do not currently ship internationally (UK only).

 Silicone Rubber Kit Economy

RTV Silicone Rubber ideal for Jesmonite, polyurethane/polyester/epoxy resin, unsaturated resin, plaster, candles and gypsum crafts, toys, soaps, statues, casting, mould making and more….

  • Two part silicone rubber kit: liquid silicone and curing agent.
  • Easy 20:1 by weight mix ratio
  • Exceptional fluidity, easy to mix, easy to de-mould.
  • Good tensile and tear strength, very low shrinkage…

Name Polysil Economy Silicone Rubber
Appearance White
Mixing ratio of curing agent (%) 5
Hardness (A°) 23 ± 2
Density (g/cm3) 1.08
Viscosity (mPas           -25°C) 21000 ± 9000
Tensile strength (Mpa) ≥4.3
Tear strength(kgf/cm) ≥25
Elongation break (%) ≥480
Shrinkage (%) ≤0.2
Silicone Rubber Kit Economy – Technical Guidelines:
  • Shake the catalyst container well before use.
  • Weigh the desired amount of base into a clean mixing container.
  • Weigh the proper amount of catalyst into the container. Mix the base and catalyst together by stirring with a stick until a uniform colour is obtained. Scrape the container walls and bottom well to insure a thorough mix.
  • Though it is often unnecessary to de-air the material due to its low viscosity, some may choose to do so. If so, place the container into a vacuum chamber and extract the air from the mixture using a vacuum pump capable of achieving 29 inches of mercury vacuum. The mixture will rise, crest and then collapse in the container. Interruption (bumping) of the container may be necessary to prevent the container from overflowing. Keep the mixture under full vacuum for 2 – 3 minutes.
  • Slowly bleed air into the vacuum chamber. When the chamber is at atmospheric equilibrium, remove the cover plate and take out the container.
  • Pour the de-aired material slowly in a steady stream from one end of the mould so that the material flows evenly over the pattern. This should minimise the entrapment of air bubbles under the flowing material.

A mould release agent may be applied on the pattern first, to improve release.

  • Allow the rubber to cure before removing the cured rubber mould from the pattern. Heat acceleration is not recommended with this product.
  • For the best results, allow the mould to air cure for an additional 24 hours before using it in production.


Silicone Rubber Kit Economy- Shelf life:

12 months from date of shipment when stored at 25°C in the original sealed packages.


Silicone Rubber Kit Economy – Catalyst Information:

Add 5% of catalyst by weight to silicone rubber base. Please use a precise electronic scale to weigh the rubber and catalyst.

Mixing proportions and temperature:
  1. Below 0°C regardless of how much catalyst is added, the rubber will react very slowly, and never fully cure.
  2. Below 5°C  the rubber will react very slowly and cannot be cured within 24 hours.
  3. Below 15°C  the working time is approx. 30-60 minutes, with a curing time of about 12-24 hours.
  4. Temperatures about 25°C, the working time is about 15-30 minutes, with a curing time of about 4-6 hours.
  5. Temperatures about 35-40°C , the working time is about 10-15 minutes, with a curing time of about 2-3 hours.
Silicone Rubber Kit Economy  – Notes:

Silicone rubber is greatly affected by temperature. The above testing data is purely for reference purposes, specific use is down to the user’s discretion. Before large scale application, it is recommended to take a small amount for testing purposes first. Once you are satisfied with the results, large scale production can begin. Polysil Ltd cannot be held liable for losses as a result of the above not being followed.


Catalyst Safety Information:

Hazard statements:
H226 Flammable liquid and vapour.
H315 Causes skin irritation.
H317 May cause an allergic skin reaction.
Precautionary statements:
P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources.
No smoking.
P261 Avoid breathing dust, fume, gas, mist, vapours and/or spray.
P264 Wash skin thoroughly after handling.
P280 Wear protective gloves/ protective clothing/ eye protection/ face protection/ hearing
P303 + P361 + P353

If on skin (or hair): Take off immediately all contaminated clothing. Rinse skin with water. P370 + P378

In case of fire: Use dry sand, dry chemical or alcohol-resistant foam to extinguish.
Contains Bis[(2-ethyl-2,5-dimethylhexanoyl)oxy](dimethyl)stannane; Methyltrimethoxysilane.

First Aid Measures:

First Aid responders should pay attention to self-protection and use the recommended protective clothing (chemical resistant gloves, splash protection).
Inhalation: Move person to fresh air and keep comfortable for breathing. If not breathing, give artificial respiration; if by mouth to mouth use rescuer protection (pocket mask, etc). If breathing is difficult, oxygen should be administered by qualified personnel. Call a physician or transport to a medical facility.
Skin contact: Remove material from skin immediately by washing with soap and plenty of water.
Remove contaminated clothing and shoes while washing. Seek medical attention if irritation or rash occurs. Wash clothing before reuse. Discard items which cannot be decontaminated,including leather articles such as shoes, belts and watchbands. Suitable emergency safety shower facility should be available in work area.
Eye contact: Flush eyes thoroughly with water for several minutes. Remove contact lenses after the initial 1-2 minutes and continue flushing for several additional minutes. If effects occur, consult a physician, preferably an ophthalmologist. Suitable emergency eye wash facility should be available in work area.
Ingestion: If swallowed, seek medical attention. Do not induce vomiting unless directed to do so by medical personnel.