casting a Banksia Pod

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Oliver Springs, TN
I had some time today and cleaned off the counter and generally straightened up the shop for the most part. I found a Banksia pod and decided to try and cast it in some Smooth-Cast 326. Smooth-Cast is a urethane resin similar to Alumilite I think. I don't claim to be an expert, but here's how I go about casting.

It says in the directions on the SC that is has an open time of 7 min. once mixed. That's plenty of time, but you can't waist time looking for something so you have to have all your stuff ready.

Here's what I generally use when I cast.materials.jpg The SC has a part A and B and is mixed at 1:1 by volume.Here it is getting ready to be mixedscale.jpg I added some blue dye, turquoise and pearlescent powders to the mix. mix.jpg

I place the banksia in a form. in box.jpg I cut the pod so that it would fit tight and wouldn't float. I was able to get two pieces that fit nicely. I marked on the form where the middle of each piece is and where the seam between them is located so when I cut them apart I can get the best blanks. I didn't get a shot of the poured form, because I mixed too much resin and didn't want to waste it so I used the excess on a single blank form that I have. I put a cutoff of the banksia in this single form and used it for the excess resin.

I placed both forms on a tray rack.jpg and put it into a paint pressure pot that I use as a pressure chamber.in pot.jpg I ran the pressure up to around 60 psi. pot.jpg Why 60 psi you might ask? The pot has a pressure relief valve that is supposed to be set at 80 psi. Well it's not or my gauge is off! I popped it at around 70 psi once and it scared the holy crap out of me! So, I stop at 60 to 65.

I'll let the resin sit in the pot under pressure overnight. I've taken them out in an hour before, but I'm not in a hurry so I'll let it sit.

That's probably as clear as mud!

John
 
:lurk: :lurk:

Probably a dumb question (but that hasn't stopped me before..)..

With something that porous is there a problem with running out of resin once you put it under vacuum? That is I'm assuming that a lot more resin goes into the piece once the vacuum takes hold so how much extra do you need to put in to make sure the pod is still fully enclosed.
 
pods cut 2.jpg

Here they are finished. I couldn't wait till tomorrow. If I do it again, I'll go lighter on the dye, it's a little dark.

Ryan, I was worried about using enough resin, so I put what I thought was more than enough, actually I could have gotten by with about 10 oz. I use pressure not vacuum. I get good penetration with the pressure forcing the resin into the voids. It's my understanding that the bubbles that are in the resin don't come out like in a vacuum, but are crushed such that you can't see them.
 
Neat color contrast though!

Thanks for the details, this is an area I know less than zero about but some of the results are pretty cool! These are looking like they could well be on that list for sure.
 
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