Bubble Blues - any ideas?

Jumpergal · 11-10-2011, 01:44 PM

When I originally sculpted the figure which I take my name from, the Jumper (actually a Canadian Forces SARtech in jump gear) I had no idea it would be so popular. Now I find myself needing to cast more than originally thought, and though the Smooth-on resin I use is just a bit thicker than water I still have some bubble issues, no matter how carefully I mix and pour. This adds to the prep time and the "darnit" factor.

I use Rebound for the mould, with Shell Shock for the mother. I have been using Smooth Cast 325 with Ease Release. I tried the primer trick that the Smooth-on website suggests but with no luck. Also tried the talc, also no luck. It's a two part mould with no sprue. Mould is 12.5 inches tall by six wide by five deep. Figure is around 11 inches tall by three wide by three deep and irregular.

Given that I will be looking at making a generous number of these, and also since I've always wanted to get into larger production of some of my other pieces, I'm beginning to think about other ways of getting bubble-free.

Vacuum? Pressure pot? Centrifuge? 3-d printing?!

What are your thoughts, friends?

FANTAMATION · 11-10-2011, 02:42 PM

when you say bubbles do you mean little tiny spherical nodules on your castings or little pinholes in the castings?

Jumpergal · 11-10-2011, 03:16 PM

Pinholes. I've managed to get the moulds made so they don't have warts, at least. But when I demould there are pinholes. Sometimes there's a thin wall of plastic with a series of pinholes beneath it.

FANTAMATION · 11-10-2011, 04:33 PM

An easy solution for this problem is to just rub the mold down with some resin using your (gloved) fingers before pouring and filling your mold, you should have enough time to do this AND fill up the mold before the resin starts to kick. Rubbing the mold with a little resin first will definitely get rid of any air bubbles that cling to the surface of the mold.

blip · 11-11-2011, 02:27 AM

Vibration will send bubbles to the top of a thick goop. About the wavelength of a hair trimmer will do it. 50Hz. Coating the inside is better though.

Jumpergal · 11-11-2011, 09:22 AM

D'oh! (slaps head) Of course! What a brilliant idea, and so simple. I was coating with everything BUT the material itself!!!!

Thanks very much. If I don't need to spend $$$ on a pressure pot or a degassing rig, yay!

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11-10-2011, 01:44 PM	#1
Jumpergal Join Date: Aug 2011 Location: Ajax ON Posts: 47	Bubble Blues - any ideas? When I originally sculpted the figure which I take my name from, the Jumper (actually a Canadian Forces SARtech in jump gear) I had no idea it would be so popular. Now I find myself needing to cast more than originally thought, and though the Smooth-on resin I use is just a bit thicker than water I still have some bubble issues, no matter how carefully I mix and pour. This adds to the prep time and the "darnit" factor. I use Rebound for the mould, with Shell Shock for the mother. I have been using Smooth Cast 325 with Ease Release. I tried the primer trick that the Smooth-on website suggests but with no luck. Also tried the talc, also no luck. It's a two part mould with no sprue. Mould is 12.5 inches tall by six wide by five deep. Figure is around 11 inches tall by three wide by three deep and irregular. Given that I will be looking at making a generous number of these, and also since I've always wanted to get into larger production of some of my other pieces, I'm beginning to think about other ways of getting bubble-free. Vacuum? Pressure pot? Centrifuge? 3-d printing?! What are your thoughts, friends?

11-10-2011, 02:42 PM	#2
FANTAMATION Join Date: Jun 2009 Posts: 243	Re: Bubble Blues - any ideas? when you say bubbles do you mean little tiny spherical nodules on your castings or little pinholes in the castings?

11-10-2011, 03:16 PM	#3
Jumpergal Join Date: Aug 2011 Location: Ajax ON Posts: 47	Re: Bubble Blues - any ideas? Pinholes. I've managed to get the moulds made so they don't have warts, at least. But when I demould there are pinholes. Sometimes there's a thin wall of plastic with a series of pinholes beneath it.

11-10-2011, 04:33 PM	#4
FANTAMATION Join Date: Jun 2009 Posts: 243	Re: Bubble Blues - any ideas? An easy solution for this problem is to just rub the mold down with some resin using your (gloved) fingers before pouring and filling your mold, you should have enough time to do this AND fill up the mold before the resin starts to kick. Rubbing the mold with a little resin first will definitely get rid of any air bubbles that cling to the surface of the mold.

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11-11-2011, 02:27 AM	#5
blip Join Date: Dec 2010 Posts: 966	Re: Bubble Blues - any ideas? Vibration will send bubbles to the top of a thick goop. About the wavelength of a hair trimmer will do it. 50Hz. Coating the inside is better though.

11-11-2011, 09:22 AM	#6
Jumpergal Join Date: Aug 2011 Location: Ajax ON Posts: 47	Re: Bubble Blues - any ideas? D'oh! (slaps head) Of course! What a brilliant idea, and so simple. I was coating with everything BUT the material itself!!!! Thanks very much. If I don't need to spend $$$ on a pressure pot or a degassing rig, yay!

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