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Making a Super Flexible Rubbery Sculpting Compound

Most customizers who’ve been reading the Modeller’s Extra know how much we love Apoxie Sculpt and its variants for most of our sculpting needs. But it falls short when you need to sculpt thin pieces that stick out into the air, like a stray lock of hair, a thin tubular accessory, or a thin flat piece of clothing. AS cures rock hard and in thick diameters is break resistant but in thin diameters is too brittle. In those times Kneadatite (Green Stuff) fills the need by being tougher and more flexible. But Green Stuff has its limits too because it can only bend so much before snapping, with thinner pieces being able to bend further before breaking. And both products have the drawback of hindering articulation if they’re used in places that drape over a joint, like making a skirt that drapes over the hip joints. Kneadatite less so but it still doesn’t give enough to allow for posing because it pushes back against bending.

So the Nerd was pondering this problem of finding a medium that can be sculpted yet will cure very flexible.

He tested Kneadatite’s claim that if you mix more of the Yellow than the Blue of Green Stuff together you get a more flexible compound. He used as much as a 3 to 1 ratio of Yellow to Blue. And while it’s true that it was a bit more flexible than a 1 to 1 ratio, a 1/16″ diameter piece still snapped in two after curing for a week. This made him sad because the various ratios of Kneadatite held out great promise of flexibility after one or two days of curing but get more and more brittle as time goes by.

At the same time he was trying to figure out a way of making Kneadatite more workable because he can’t blend or sculpt with it worth a dime. Somewhere in the cobwebs of the Nerd’s aging brain he remembered way back when he first found out about the various sculpting compounds from the various sites on the web, and he remembered that at a couple (though he couldn’t remember which) saying that you can mix Kneadatite with other two-part epoxies to marry their features. Mixing Kneadatite together with Milliput was used (these sites hadn’t yet discovered the magic of Apoxie Sculpt which was why they used Milliput in the example). So the Nerd mixed up a batch of Kneadatite on the left hand and a batch of AS on the right hand and he combined these two together like he was trying to invent Reeses Peanut Butter Cup (you younger readers won’t remember the old 70s TV commercials where one guy eating peanut butter would run into some guy eating chocolate and they’d say “You got peanut butter on my chocolate,” and “You got chocolate in my peanut butter,” and the narrator would come on about a new candy called Reeses that was that exact combo).

Now the Nerd didn’t expect this to make a super flexible sculpting compound but bear with him for a bit because he was shooting for something else at that time. What it did make was what at first seemed like a best of both worlds scenario between AS and Kneadatite. The mix was easier to handle than Kneadatite, having the smoothing and blending capability more like AS. After a day of curing it seemed like it had the half-way flexibility between Kneadatite and AS as would be expected. But after a few more days it became less flexible and thin pieces broke at bends that aren’t much more than what regular AS by itself would break at. Ratios of 3 to 1 Kneadatite to AS still produced the same result. So while the mix was more workable than Kneadatite, it didn’t have the toughness. And it didn’t have quite the same ease of use as AS. So really that mix wasn’t worth the effort since it sort of diluted the strengths of either compounds.

So the Nerd felt like he was a bigger loser than normal at this failure. Then he remembered something about two-part compounds: one part of the compound is the catalyst and the other part is the hardener. This is true of two-part putties as well as those syrupy epoxies. Then the Nerd said to himself, he says: “Nerd, you need to play mad scientist if you’re going to get the chicks.” So he decides to try mixing catalysts and hardners between AS and Kneadatite. Now AS has a Part A and B, and Kneadatite has Yellow and Blue, and the Nerd has no idea which is the catalyst and which is the hardener so he tried all four combos: AS’s Part A compound with Kneadatite ‘s Blue, B with Blue, A with Yellow, and B with Yellow.

The wrong combo of catalyst-catalyst or hardener-hardener was A-Yellow and B-Blue. Those wouldn’t cure at all. The combos that cured were A-Blue and B-Yellow. A-Blue resisted mixing together like water and oil and finally came together with much kneading and alot of mess. It’s pretty much a useless compound because it had all the bad qualities that doesn’t exit in AS and Kneadatite. It had a hard time sticking to things, it was hard to get detail in, and it resisted blending into its surrounding. It dried rock hard, which meant that thin pieces broke instead of bent. But B-Yellow…now that was a different story.

After mixing, B-Yellow was very sticky, like chewing gum sticky. But like its parents you only need to dampen your fingers and tools to keep it from sticking to yourself. It was very blendable, even more so than AS because it can spread out thinner. It smooths beautifully. It doesn’t take detail or sculpting anywhere as well as AS, and a little less so than Kneadatite, but it’s still workable with some practice. The Nerd only tested trying to put detail in right after mixing and didn’t do time interval tests, so it might take detail better as it cures much like AS and Kneadatite would. It cures in about 2-3 hours. But the magic came after it cured. After one day of curing this hybrid was more flexible by far than its parent Kneadatite. The other thing too is that instead of springing back straight to shape, it has a tendency to hold the bend it was placed in and slowly move back to its cured shape. Very thin pieces would actually droop along with gravity over time. And best yet, even after several weeks of curing it remained flexible instead of slowly hardening. It also remained soft enough that you can score in lines with your fingernails even after it’s dried and cured all this time. And it took paint as well as cured AS or Kneadatite.

Being the mad scientist that he is, the Nerd tried different ratios of B to Yellow. It doesn’t make that much of a difference until you get too disproportionate. At a 3 to 1 ratio of Yellow to B, the mix doesn’t really cure. It remained a bit sticky even after weeks and will stick to paper enough to peel off a thin layer of the paper if left on a sheet. This 3-1 ratio of Yellow to B can also be squished back to itself so that you can actually press 2 dried pieces together and knead them back into one. The Nerd can’t really see a use for such qualities but you might. A 3-1 ratio the other way, more B to Yellow, cured but is more springy. A 1/8″ thick piece when bent back on itself takes a larger arc to accomplish it than a 1-1 ratio. So the Nerd recommends going only as far as 2 to 1 ratio either way. With Kneadatite being more expensive than AS, he thinks using a 2 to 1 ratio of AS’s B to Kneadatite ‘s Yellow would produce the most cost effective result.

So while the Nerd didn’t find a way to make Kneadatite more workable or AS more flexible at thinner pieces, he did accidentally discover the other thing that he was pondering, which was a super flexible sculpting compound. Now we should be freed of having to steal rubber hair from other figures and instead can sculpt our own to any length and shape we desire. Bendable tails should be easy to do now if a wire is used and B-Yellow sculpted around it (though it sure would be expensive). Maybe someone will even tackle Medusa with bendable hair using wire inlaid B-Yellow. Hope all the genius customizers at Fwoosh can make use of this and expound on it.


A rolled piece approximately 3/16″ diameter being bent back on itself


A near paper thin piece being bent back all the way to the point of folding on itself 


Hair test. First pic is the sculpted position after curing. Second pic shows it bent back. Third pic is after being let go after bending; the hair will keep this shape for a few minutes and slowly start to move back. Left on a table it ended up moving back halfway to the cured position in the first pic and stayed there. If it was on a figure where gravity was pulling down on it, it would move all the way down and drape over the the figure’s back. 



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