# Casting a pine cone



## Frank A

I recently tried to expand my casting skill set to include pine cones and I looking for some tips.

My attempt to cast this involved a larger pine cone (approx 2 x 2 x 6) in a like sized mold I made. The pine cones had been soaked in denatured alcohol and then dried and stabilized six months ago. My casting material was Alumilite clear that I colored using mica powder.

So the process I used was to get my mold and pine cone ready (but I didn't have the pine cone in the mold yet), mixed and colored my Alumilite then I filled the mold about half full. I wanted to have a bunch of the Alumilite in the mold for the pine cone to push down into to hopefully avoid any issues with the resin flowing around the bits. Once the pine cone was in I topped off the resin and put it into my pressure pot and took it up to 55psi. Total time from the start of the mixing process to the pot being under pressure was about 4:45. The left over resin in the cup was still quite fluid so I felt pretty good about getting it done fast enough.

When I demolded the casting about 5 hours later it was good and solid and showed no sign of any bubbles at the surface but when I turned the casting over to what would have been the bottom of the casting I noticed what seemed like to small surface divots where there was a thin skin of resin but to the touch felt retty solid underneath.

I let the casting sit overnight and today I trimmed it up and cut it into two pieces for bottle stoppers. I prepped and mounted the first one on my lathe and trimmed it into a round before beginning the shaping process. When I stopped the lathe after it was rounded that is when I was able to see that a number of the voids extended deeper than I though. I filled them with CA so I'm sure the blank will still be usable once it dries but I'm curious if anyone has any idea what might have caused this or how to better avoid it in the future.


Thanks,
Frank


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## Sprung

Frank, I have no experience on the casting end of things, but I have turned cast pinecone blanks, as well as other blanks that contain similar organic material with lots of natural voids - sweet gum pods, seeds, etc. Every such blank I've turned has had voids to some extent - to some extent, it's the nature of the beast, at least that has been my experience.

What is the working time on the Alumilite? Is there any possibility of vibrating the piece, either before it goes into the pressure pot or while under pressure in the pot, to help release some of the air bubbles?


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## Frank A

The rated pot time is 7 minutes so its possible that I could have done something to vibrate it and that might be something to try next time if I can prep it as quickly as I did this time.


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## Schroedc

Pushing it down into resin will push some into the voids but unless there is an air path for the air to come out the top it'll still trap some in the pine cone just under pressure the voids will be smaller. One possibility would be to cast them inside a piece of PVC pipe with the openings on the cone pointing up to allow the air in the cone to rise out through the resin maybe? Not sure how fast the bubbles float out in Alumilite with the shorter working time, they'll usually float up and out within 10 minutes using Silmar but I haven't used Alumilite myself yet.....


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## Frank A

Schroedc said:


> Pushing it down into resin will push some into the voids but unless there is an air path for the air to come out the top it'll still trap some in the pine cone just under pressure the voids will be smaller. One possibility would be to cast them inside a piece of PVC pipe with the openings on the cone pointing up to allow the air in the cone to rise out through the resin maybe? Not sure how fast the bubbles float out in Alumilite with the shorter working time, they'll usually float up and out within 10 minutes using Silmar but I haven't used Alumilite myself yet.....



Interesting, I know they make a version of Alumite Clear called Alumite Clear SLOW that increases the pot time to 12 minutes. I'm not sure if there are any disadvantages to using that formulation but perhaps that combine with your idea would allow me to better get any voids out.


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## Schroedc

Pardon my horrible sketch but this is what I was trying to get at in my earlier reply.....

Reactions: Like 2 | EyeCandy! 1 | Great Post 1


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## rocky1

I ain't gonna say nuthin!!! It's really tough; but I ain't gonna say nuthin!

Reactions: Agree 1


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