RTV silicone rubber for artificial stone molds
INTRODUCTION of RTV silicone rubber for mold making:
Our RTV silicone rubber for mold making,is normally of milk white color and in a viscous liquid state. It is composed of 2 parts(A: silicone rubber,B: curing agent),which are mixed in a proper ratio and react to turn solid during some curing time. It embraces 2 categories,namely condensation cured type and addition cured type. In order to cater to different applications and customers,we have various items with different hardness depending on customers' requirements. Our products are applicable to multiple fields and purposes,including candle casting,resin casting,polyurethane casting,gypsum product reproduction,life casting,metal casting,concrete casting,etc.
OPERATION PROCEDURES of RTV silicone rubber for mold making
1. Stir the liquid silicone (Part A and part B) well before use (except when depending on machine).
2. Weigh the desired amount of part A into a clean mixing container,and then weigh the proper amount of part B into the container. Mix the two component together by stirring with a stick. Scrape the container walls and bottom well to insure a thorough mix.
3. Though it is often unnecessary to deair the material due to its low viscosity and our special formulation,it is better to do so to obtain a bubble free rubber. If so,place the container into a vacuum chamber and evacuate the entrapped 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 vacuum may be necessary to prevent overflowing the container. Keep the mixture under full vacuum for 2-3 minutes.
4. Bleed air slowly into the vacuum chamber. When the chamber is at atmospheric equilibrium,remove the cover plate and take out the container.
5. Pour the deaired material slowly in a steady stream from one end of the mould so that the material flows evenly over the pattern. This should minimize entrapment of air bubbles under the flowing material. A "ready" mold may be poured firstly over the pattern,which will also help reduce the possibility of entrapping air on the pattern and in the cured rubber. A mold release agent may be applied on the pattern first to improve release.
6. Allow the rubber to cure for 2-4 hours at 24C before removing the cured rubber mold from the pattern. Heat acceleration is recommended if necessary
TECHNICAL GUIDELINES of RTV silicone rubber for mold making:
1. To choose suitable hardness, It depends on two factors:
1) First one is the size of the mold to be made. if it is large,we need to choose the higher hardness,such as 40,45,50 (shore A).otherwise,we need to choose soft silicone rubber with hardness of 10-35(shore A).
2) Second one is about the details of your application,if the shape or design is complicated; We need to choose soft hardness, as soft rubber can tightly match every small corner of the master mold. Otherwise,hardness of 30,35 or Higher is preferable.
2. To choose proper viscosity
Generally speaking,it depends on whether you have a vacuum chamber. If you have a vacuum chamber,viscosity is not a problem,Or, Comparable low viscosity is preferred ,as bubbles can be easily released in this way.
3. To choose wanted Color
We also have our own pigments to match with the silicone rubber. If need be,it will be our pleasure to sell you colored silicone rubber,or you may do the dying process by yourselves. Just choose the best way for you.
SHELF LIFE of RTV silicone rubber for mold making:
12 months from date of production when stored at 25°C in the original sealed packages.
PACKAGE of RTV silicone rubber for mold making:
Packed in clean pails, 25kg/pail,200kg/pail.
QUALITY WARRANTY of RTV silicone rubber for mold making
We promise that quality of goods will be 95% same as sample
| 635#|| 630#||625#||620#|
|Mixing proportion of curing agent (%)||5%||5%||5%||5%|
|Operating time (mins 25 0C )||40~70||60~90||40~70||30~50 |
|Curing time(hours 25 0C)||4~7||5~7||4~7||3~5|
|Hardness (A°) ||35±2||30±2||25±2||20±2|
|Viscosity (Mpas -25 0C)||30000~38000||27000~32000||17000~19000||12000~14000|
|Tear-strength (KN/m)|| ≥30||≥30||≥27||≥32|
|Elongation-break(%)||≥420||≥440|| ≥440|| ≥420|
|Linear Shrinkage (%)||≤0.3||≤0.3||≤0.3||≤0.3|
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