Swelling mold and masters

Questions about Making Your Own Lures

Swelling mold and masters

Postby Remixfly » Tue Jan 08, 2019 7:29 am

Have a project I’m working on and have successfully shrank molds and been able to pour Alumilite white masters from for remolding but am having tons of issues swelling a mold and getting anything resembling a usable master. I am assuming that my issue is the exothermic curing is drawing the oderless mineral spirits into the Alumilite causing my issues. What would be best guess to help remedy or is the another product/material that would perform better? I would prefer a rigid master but am open to suggestions.
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Re: Swelling mold and masters

Postby dahlberg » Tue Jan 08, 2019 12:21 pm

Hmm, I've done one mold a few years back to make a mag rapala about 25% bigger. I sure don't recall having any curing issues with the resin afterward, but I don't recall for sure which rubber I used. Might have been quick set. I do remember having issues with tearing if i wasn't really careful.
This looks like a question for Mike the Goop King. How large is the object you are making? have you tried heating the mold a bit?
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Re: Swelling mold and masters

Postby Remixfly » Tue Jan 08, 2019 1:24 pm

Thanks for the quick response. The parts I am making are fairly small so I have been heating molds. All the details are there in the mold but the casts show very little of it as well as bubbles in the casts that disfigure parts. I have noticed that the mineral spirits are cloudy and I’m wondering if the cloudiness is from moisture and that’s what’s causing the issues to an extent.
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Re: Swelling mold and masters

Postby dahlberg » Wed Jan 09, 2019 11:50 am

I think that might be a pretty good guess. It doesn;t take much moisture to mess up the urethane.
hope you get it worked out!
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Re: Swelling mold and masters

Postby dahlberg » Wed Jan 09, 2019 12:17 pm

I think that might be a pretty good guess. It doesn;t take much moisture to mess up the urethane.
let us know if you cant get it worked out!
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Re: Swelling mold and masters

Postby dahlberg » Wed Jan 09, 2019 12:17 pm

I think that might be a pretty good guess. It doesn;t take much moisture to mess up the urethane.
let us know if you cant get it worked out!
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Re: Swelling mold and masters

Postby Remixfly » Thu Jan 10, 2019 6:37 am

I let the swollen mold sweat out a bit then gave it another shot after heating and I got a very clean reproduction. Approximate 20-25% which is good for what I’m wanting. I’m thinking it had to be moisture causing my headaches. Thanks for the help it was greatly appreciated.
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Re: Swelling mold and masters

Postby dahlberg » Thu Jan 10, 2019 11:33 am

Glad it worked out! What are you making if you don't mind my asking?
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Re: Swelling mold and masters

Postby Remixfly » Mon Jan 14, 2019 3:29 pm

Sorry Larry, I just saw this. I am making a series of heads for streamers. So far they have been extremely well received but I’m in the infancy of this project and still testing durometers and wall thickness. I really don’t have a way to show photos other than direct posting which isn’t supported if I’m correct.
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Re: Swelling mold and masters

Postby dahlberg » Thu Jan 17, 2019 5:51 am

I got the pics you sent. Excellent! I've shown this stuff to several tyers and just hinted at some of the possibilities and none of them have picked up on the potential. Glad to see you've got your thinking cap on and running! I've been mixing a few microballons into the rubber and it seems to improve the consistency. Also mixing it with FlexFoam and a few balloons in various proportions and getting excellent results in controlling buoyancy.
keep on gooping!
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