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Heat Resistant Foam
7 replies to this topic
Posted 16 January 2006 - 07:57 PM
I need some foam that, once cured, can resist 350 degree plastic. I'm using a 2-part bondo mold to pour the foam in. I've been experimenting with 8lb urethane foam, but once it gets much above 150 degrees it starts expanding, cracking, and much worse releasing tons of gasses. It doesn't seem to matter how long I let it cure, I just tested a piece that I poured two weeks ago and had equally bad results. Coating it with epoxy doesn't help.
I need something that can be poured into a 2-part mold, is buoyant, reasonably tough, and won't react when melted plastic is poured next to it.
Thanks for any ideas...
Posted 16 January 2006 - 10:50 PM
This lure will be poured out of soft plastic. The foam will be for floatation only, and is suspended inside the soft plastic. I have a 4-part mold for the soft plastic bait, and the cured foam piece is suspended inside of it when I pour the plastic in. Hope this makes sense...
Posted 17 January 2006 - 08:56 AM
hi, i'm no foam expert( just starting out actually) but a search look on the smooth-on website turned up a possible product called "Flame Out 7 Flame Resistant Rigid Foam" - i think its more costly than normal foam though.
Posted 17 January 2006 - 12:01 PM
The Flame Out foam might work, I emailed Smooth On to see what they have to say.
Balsa would be too time-consuming. It's a rather irregular shape that has to be very precise and also has a bent piece of wire going through the center.
I was looking around at epoxy mixed with microballoons last night, that might work if I could find some really cheap, low viscosity epoxy.
Posted 17 January 2006 - 01:43 PM
Here's the response I got from Smooth On. I guess foam is out. Are there any other alternative materials for casting hard baits?
Thank you for your inquiry. Flame out foam will not burn, however Urethane foams are not high heat deflection materials. The symptoms you have described are typical. Usually about 150 F max is all you can expect out of a Urethane foam.
Posted 17 January 2006 - 02:13 PM
You're gonna have that problem with any porous float you try. The micro balloons might work. As I'm sure you know micro balloons are small glass spheres that contain air. For a medium to cast them with you could try smoothcast 300. It's one of the lightest resins I've found. You can tie a rattle to the harness and encapsulate it in the float before casting the plastisol