Clint M

Why Would My Rubber Mold Play Out?

9 posts in this topic

I have poured maybe twenty five baits out of my mold and all of the sudden the lures start sticking real bad to the sides of it. Next thing you know it tears chunks out of my mold. What went wrong? Have had no issues until now.

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are you pouring polyurethane in a silicone mold? and yes are you using any mold release?

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Try spraying a light coat of Pam cooking spray in your mold before pouring your resin Clint. Not enough that it leaves puddles in the bottom of the mold, but just enough to coat it. You'll need to be sure to wash your castings before painting them though.

Ben

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Well ive had to make a new mold. I tore out chunks of my old one. Guess I will keep it for sentimental reasons. BTW found some cheaper closer mold making material. Ill send you a message. Its outta Mississippi.

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I have been told that Silicone and polyurethane chemically react to each other and after so many pours chunks will start breaking off. No way to stop it, but mold release will help slow that down. Mold release works real good. I haven't poured 100 times in any one mold to see what happens. I did have some Mold Max 60 from Smooth On that did break chunks off premature. I thought there was something wrong with the Mold Max because it was sooo thick for mixing. I had to take the stuff out of the jug with a putty knife. when set it is a hard RTV silicone.

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So do you have an aluminum one produced or what is your options. I dont want to have to keep making molds. It slows me down too much.

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I only did prototype work with the polyurethane and RTV. I had so many problems I had to quit. I made some spin cast molds to cast polyurethane and on the parts, the micro balloons would stay in the center of the mold and the heavy stuff would be on the out side of the mold where the parts were at, so they wouldn't float.. then tried the RTV and was having trouble with air bubbles in the polyurethane because of the fill gate location.

I really like the mold release. It looked like it would extend the mold life.

I don't know what to use for a mold, maybe someone knows, something like Delrin that could be machined. that stuff is expensive.

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