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21 April 2016
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Silicone Technique
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Operations of silicone rubber

 

Step One: Preparation of the Original molds
Firstly, you should deal carefully with the Original mold or the products you want to be molded. If

no polishing of the Original mold or the products you want to be molded, the surface of it is not

so smooth or perfect, then the products madeout of silicone molds will be not up to standard.

 

Step Two: Take 100g of part A(silicone rubber) and add 2g of part B(curing agent) and mix two

parts evenly.
Notes1: Moulding silicone rubber is a kind of flowing liquid and it contains two parts. Part A is a

kind of white flowing liquid and part B is the curing agent. Remember to mix part A and part B

evenly, otherwise the silicon rubber will be partly solidified and this will give birth to difficulties in

your final operation. What’s more, the finished moulds will meet a short life. All of these will

cause a waste of silicon rubber.

Notes 2:the weight of the silicone and catalyst should be weighted correctly. According to local

weather, the mixing ratio can be 100 to 2 under room-temperature 25 0C; if the local weather is

about 10 0C, then the maximum mixing ratio should be 5%;When local temperature is -5 0C, no

reaction will happen between the silicone and hardener; once the temperature of local weather is

38-45 0C, the mixing ratio of silicone and curing agent should be 1 %.

 

Step Three: vacuum pumping
Without exception, this step takes about 2-3mins,less than 10 minutes. Otherwise, it will cause

cross linking reaction, and no more further steps will be available.

 

Step Four:Brush or Pour the silicone rubber

4.1 Brushing cast:
a. Evenly brush the mixed silicon rubber on the product which is covered with mold spray with a

brush or a brush pen.
b. After the cross linking reaction (about 30 minutes), brush a second coat which can increase

the tension and tear strength of the mold.

c. Cover a glass cloth on it after another 30 minutes of a second cross linking reaction, and use

a brush pen or a brush to avoid any interstices.

d. Cover a third coat.
(Note: if you have high requirements for the tension and the tear strength for the mold, please

repeat step c and step d. Hence, the finished silicone moulds will have a good quality and a

longer life, which can help you save cost and increase production efficiency.)

4.2 Perfusion/Pouring moulding:
It is suitable for simple products with the smooth surface.Without any mold lines,which helps you

save time and is easy for operation.Evenly and slowly perfuse the mixed silicone rubber into the

square fram.After the cross linking reaction and the silicone rubber turns dry,you can take the

products out.Thus,the mold has been done.

(Note:we usaully use soft silicone rubber to make molds by perfusing,which is easy for

demoulding and will not damage the product in the silicone molds.)

Step Five: Operations for the external mold
a. Make a square frame with four pieces of wooden boards or rubber plates, then place the

product which is covered with the finished silicon rubber mould in the middle.

b. Slowly and evenly perfuse the gypsum into the square frame. Also you can brush the resin on

the product which is covered with the finished silicon rubber mould with a brush or a brush pen.

Repeat this process two or three time after the cross link reaction.

 

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