Custom Toys and Action Figures by Blayne

Thursday, March 7, 2013

How To: Work with Kneadite ('Green Stuff') sculpting material

I recieved a comment on my Hellblazer John Constantine custom over at TFW2005 recently:

Dude, Blayne!I think this is the best thing I've seen from you, bro!That is killer work! I purchased the Citadel Green Stuff but have no idea how to use it without wasting it. Lol! I mean I bought the whole sculpting tool kit too. So, is the head on John here completely sculpted from scratch or is it just the hair resculpted on top of the other head?

I decided to do cross-post some explanation about Greenstuff/Kneadite here, as it pretty different to work with compared to Aves Apoxie sculpt.

For this Hellblazer John Constantine custom, I dremmeled down the original hair and part of the face. I think there was some minor Aves sculpt work done on the cheeks/scar to fill them out, and the rest was Green Stuff.

As for Citadel Green stuff, it also goes by Kneadite. I buy mine in a spool on eBay. It's the same thing as the official 'Citadel' brand you'd find at at Warhammer shops, but it's much cheaper, and you get more for your money when purchasing online.

To properly use Kneadite, there's some things you should keep in mind:

Unspool the green stuff (or just lay it out flat), and use a hobby knife to separate the yellow/blue sections.  Trim about 1 mm on either side of the divide. The Yellow and Blue halves have a tiny bit cured where they touch, so trimming that thin cured bit right out before you mix it presents chunks of hard sculpt turning up unexpectedly as you sculpt.

Press/fold/press/fold the 2 pieces together until it's a uniform green color with no swirls. From there, it'll be really sticky for a few min. Add sections to whatever you're sculpting, bit by bit. When sculpting detail, get the rough shape you need, then wait a few minutes for the material to firm up, allowing it to keep detail better, and stick less to your sculpting tools.

For all my sculpting, I use a hobby knife (with Excel #11 disposable blades) + silicone 'clay shapers' + some water to sculpt. Some people use saliva, but that's... well, 'personal preference'. I keep a waterbottle nearby with an upturned cap. I've heard of some people using those stamp water-wheels to wet their fingers just enough to smooth the sculpt. Be careful about adding new pieces on top of where you've applied water - it won't stick with that water in between.

Unlike Aves Sculpt, Kneadite doesn't really stick well to it's self once it's started to firm up. It will, but there will always be a seam line (and a slight weakness if stressed along that seam), unless that piece was added while it was still in it's 'sticky' phase.

Try to work in manageable sections. I did the Hellblazer custom's hair in Kneadite during 3 sessions over 3 days. I leave things to cure for a full day, just to ensure things aren't damaged/shift when trying to sculpt over something that's 90% cured. When sculpting with Kneadite, add what you need, and focus on a specific area. If you're sculpting the hair on your custom figure's head, consider only sculpting the bangs, and the next day (or a few hours later) sculpting the next section. However, if the sculpt is layered (many small bits of hair, etc.), consider sculpting the entire overall shape at once, then going back and adding detail pieces after things have cured.

Kneadite is very... rubbery to sculpt with, making it ideal for hair, faces, and other things. It doesn't blend, so avoid trying to smooth it off to blend/feather into another surface - it won't work. Also, if you sand it down to nothing to achieve that blend to the base figure (this works with Aves) - but Kneadite will actually peel/fall off if it's too thin.

You can actually use this to your advantage. For example, I sculpted claw-like nails on a ninja turtle figure using Kneadite - they cured, and popped right off with a bit of pressure (due to the type of plastic Playmates uses to make their new TMNT figures). I put a drop of gel-type superglue on the finger, and replaced the cured kneadite fingernail. Rock-solid now.

Kneadite (Cons):

  1. Kneadite can pick up fingerprints easily - be sure to smooth these out before the material cures to far.
  2. Kneadite doesn't sand well. It's similar to trying to sand soft 'cape' plastic. It's possible, but the surface afterward is rough and 'pilly'. Try to achieve your final surface on your last layer.
  3. Kneadite can't smooth/blend well into anything. This goes hand in hand with not being a good material to be sanded. Make sure your sculpted section has clearly definined edges to to this into a benefit.
  4. Kneadite doesn't cure well to it's self in multiple stage sculpting. It's best to sculpt a defined area all at once.
  5. Kneadite has a small cured section between the unmixed Yellow/Blue A/B parts. Always cut this away to avoid hard pieces surfacing as you sculpt.

Kneadite (Pros):

  1. Flexible! This is the closest sculpting material to flexible plastic I've ever used. While Aves Sculpt can sand well (unlike Kneadite) - Kneadite has a flexible 'give' to it that Aves and other sculpting compounds lack. In small areas prone to bumping) tips of hair, nose, hands, boots, accessories, thin sections that overhang), Kneadite has some flexability. The same areas if dropped, or bumped when sculpted with Aves (rock hard) will actually chip, or snap. This is why Aves is excellent for overall construction on the main body of a figure, or for gap-filling, while Kneadite is good to sculpt defined details on top of a figure.
  2. Kneadite can cut/trim easily. As long as you have an ultra-sharp blade (#11's work great), 'whittling' down your sculpt in some areas (for hair, edge cleanup/trimming, or for adding battle damage, usually) works well vs. the rock-hardness of cured Aves.
  3. It's initial rubbery firmness creates realistic clothing/wrinkle/bunching up/ effects faster than Aves.
  4. When Aves has a tiny bit of water added to it's surface (during sculpting), it actually becomes very soft / 'gooshy', or and paste-like if too much liquid is added. However, Kneadite won't absorb the water - adding some just helps ensure a smooth surface.