A problem with flowing liquid from the silicone

[Mustafa]

Hi all


I,m sorry if i post in wrong section


Kindly freinds

I maked a mould with silicone but after a while some liquid or oil flow from the cured silicon i wiped it but again comes

If i poured my fda silicone in thetmold the liquid/oil will flow again and make ihibits with silicone near to the master surface

Any idea freinds

 

[modelcitizen]

bad silicone OR not properly / thoroughly mixed. make a new mold.

 

[Duncanator]

Curious, it appears that the silicone is sweating something out. My first guess is also that you have a bad batch of silicone.

Do I understand correctly that you are casting silicone parts from your silicone mold?
If so, it could be a problem if you are using different types of silicone. There are basically two types of silicone (Tin based and Platinum based) and they don't play nicely together.

 

[Duncanator]

Can you explain a little more about what you are using and doing? It's hard to diagnose from your short description.

 

[robn1]

It could be a bad batch or a bad mix, but there are mold rubbers that have a mold release mixed in which sweats out to release the cast part. I once used some Smooth-On Urethane mold rubber like this without knowing about it, drove me crazy trying to clean up the oily residue.

 

[Duncanator]

there are mold rubbers that have a mold release mixed in which sweats out to release the cast part.

Now that sounds like a possible diagnosis!

 

[modelcitizen]

hm. i would then suggest reading the properties sheet....

 

[Mustafa]

bad silicone OR not properly / thoroughly mixed. make a new mold.

Thank you all freinds

Really i maked 4 moulds and all same problem

I,m using a steel bowl to mix with a spoon for i be sure i,m mixing very good

For that i think it,s from the silicone i bought

It is from china


Here i have 2 problems


I can make moulds without problems with

the silicone (Not the FDA) but it sweating
---------------
Now the mould ready for casting with fda silicone
---------------

You put the FDA silicone but not cure

For 2 reason maybe

1/ contact with the sweating
OR
2/ these 2 Kinds of silicone not suitable togeter
And here you can not use release agent
( Release agent+sweating ) -__-

Second

I tried to make mould with FDA silicone (no sweating)
But it didn't cure fully



No way to stop the swating??

 

[robn1]

I'm assuming FDA silicone means food safe? Those types are platinum silicones and they are very sensitive to certain materials, especially sulfur. They won't cure if they are in contact with sulfur (common in clay) or some other materials. Even master parts painted with certain paints will inhibit the cure and I avoid platinum for that reason. I found that it will cure against painted parts if I left it for a few days, but that's a long time to wait. A good tin silicone may take overnight to cure but at least it's done.

If you need a food safe silicone you don't have much choice though, I'd suggest you check it after two or three days and see if it's cured then. If so try again and let it sit a few days.

 

[rbeach84]

Always learning something new here!
Regards, Robert

 

[MangyDog]

Cant high humidity cause this to happen too?

It sounds like you're from China, from what little i know there are some extremely humid places in china....

 

[Mustafa]

Cant high humidity cause this to happen too?

It sounds like you're from China, from what little i know there are some extremely humid places in china....

Hi

I,m from middle east (Gulf) it is same about the humidity

But the weather these days without humid

I found something about the sweating in same the factory site in FAQ section

I didn,t understand fully ( I don,t know full english ) but it seems it is not a problem and it is normal with this product?

 

[modelcitizen]

obtain the data sheet for the specific product and read it. there's obviously a babel thing happening here. read up on the products before you buy them to know their properties. there are many differing types of silicone...which did you buy?