[Katherine Swift]

This question comes from Jody:

So I’ve been doing resin (Epoxy) for over a year now. I got pull after pull after pull. Then all of a sudden, my molds were withering. brand new molds would last 10 pulls and that has been consistent, 10 to a mold be it my mold I made myself or one I bought in from elsewhere.

At first, I had someone tell me it was how I made my molds. This can’t be though, because even ones I’ve bought in are doing it.

Basically, the pink silicone turns white and then it sticks, mold release agent or not. Something has changed. I’m wondering if it is my resin, has something changed in it that it is killing my silicone? I can’t fathom what would cause my molds to suddenly only get 10 pulls.

[Katherine Swift]

Hi Jody,

I’m sorry to hear this is happening to you. I have a few more questions:

What brand of resin are you using?
What else are you including in the resin?
What mold release are you using?

[Jody]

I’m using K36 resin (also known as Araldite® Kit K36 )

Including Barnes Opaque pigment (for epoxy resins)

No mold release, I never needed to…. till now.

[Katherine Swift]

Hmm. It sounds like maybe it’s getting too hot? What are the minimum and maximum recommended mixing amounts?

[Jody]

No heat, very small volumes, 2.5ml in the mold to 10ml at a time. It still takes the normal setting time. Ratios are correct.

It’s 100ml resin 50ml hardener ratio for example.

[Katherine Swift]

Unfortunately, I’m out of ideas at this point. Have you asked your silicone and epoxy resin manufacturers for their thoughts?

[Jody]

I did. They said they have no idea why either. At first they said it was how I made my molds. But I make it according to the instructions. My method has not changed. I bought molds from elsewhere, and the resin did the same to those.

My hardener has gone yellow which I’ve since learnt is oxidation but the manufacturer said that won’t affect anything.

I’ve been doing this for over a year, and something has to have changed, but I don’t know what or why the resin would destroy the molding after just 10 pulls.

[Author]

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