Casting fish fins with resin

[kstenzel]

Has anyone casting fins with resin ever used anything to attempt to soften the cured fins and perhaps make them more flexible? Have been having some issues lately with hard brittle fins cracking & breaking and just wondering if any additive exists that would help.

[Jknuth]

Has anyone casting fins with resin ever used anything to attempt to soften the cured fins and perhaps make them more flexible? Have been having some issues lately with hard brittle fins cracking & breaking and just wondering if any additive exists that would help.

From what I understand you can use acetone to thin it a bit and make it flexible. I really havent tried it yet.
Try calling the tech people at Us-composites and see what they have or suggest.

[Dondi]

Has anyone casting fins with resin ever used anything to attempt to soften the cured fins and perhaps make them more flexible? Have been having some issues lately with hard brittle fins cracking & breaking and just wondering if any additive exists that would help.

Fin Magic or IE 3025 will give you firm fins with some flex.

[kstenzel]

Thanks Josh, I think I will try that Monday and see if they have any suggestions. Actually it was your blank that gave me the idea because your fins seem more flexible than the ones I have been producing lately.

[Jknuth]

Thanks Josh, I think I will try that Monday and see if they have any suggestions. Actually it was your blank that gave me the idea because your fins seem more flexible than the ones I have been producing lately.

Let me know what they tell you, I keep forgetting to check with them until its around 2:00 am then forget in the morning.
lol
As far as my blank I am just using bondo brand polyester resin.
Your fins seem fine to me, what brand are you using.

[kstenzel]

Think I may have answered my own question. US Composites wasn't of much help, but I called Eager Polymers & they had several suggestions. First was a Liquid Plasticizing Agent EP9009 that sounds like it might do what I am looking for although eventually (perhaps years down the road) it will become hard & brittle again. Their second suggestion was adding Fiberglass Flock, a finely ground glass (1/32") that can be used like Cab-o-sil only it will add strength. Think I will try both of these & see how they work

[clifftax]

Think I will try both of these & see how they work

So whats the verdict ?

[duxdog]

I have been using vinyl resin vs poly resin for my fins lately. A guy at the boat repair shop that has been working with resins for 35 years offered it to me to try.It is very flexable. I am very pleased with the results.

[Cory]

Duxdog, does the vinyl resin stay flexible or once you position it does it hold its place and become firm again?

[kstenzel]

Adding the EP9009 & fiberglass flock to the polyester resin seemed to make little or no difference as far as I could tell... Would be interested in hearing more about the vinyl resin too.

[Pescado]

IE 3025 is the best I have used. Strong, even when paper thin. Heat will soften, so you can shape however you want. The IE 3080 (i think that's the number) is the same with more working time. If someone has a better material I would like to see the finished cast side by side.

 PB

[Dondi]

IE 3025 is the best I have used. Strong, even when paper thin. Heat will soften, so you can shape however you want. The IE 3080 (i think that's the number) is the same with more working time. If someone has a better material I would like to see the finished cast side by side.

 PB

Paul,
 I agree IE3025 is a great fin casting product....depending on the type of mold you will cast your fins in. I use a 2 sided flexible urethane mold for fins. I prefer a paste that I can spread vs. the water thin, viscosity of the IE3025. That is the main reason I use "Fin Magic". That along with the fact that I get good results from it.
 So I think the type of mold you will be using should be a consideration as well...

[duxdog]

Sorry guys I haven't responded back. I have been on the river. The vinyl resin heats up with hot water or a heat gun and then is ridgid after it cools. I like the results I get with it. I do not have a vacuum chamber and had bubble issues with the polymers. and the cost of a quart of resin is very inexpensive.