Monday, October 29, 2012


This year's Halloween project was an Alien chesterburster.  It took 3 or 4 weekends for me to do completely from scratch and even though this was the second or third time I've done somethin' like this with my Dad, I still wasn't completely sure if it would work.  I'm not a sculptor at all, but I very much enjoy the process of casting and molding.

And so, here's a slew of pics that I took along the way.  Enjoy!

It started with this doodle.  The plan was to sculpt somethin' that looked like this, cast it length-wise in plaster, then use that mold to pour a latex replica.  The circles in the doodle represent spheres that I would use to "key" the two halves of the mold.  We've done this before using rubber balls with great success, but this time me botched the casting process a bit.  You'll see.

I approximated how big the burster would be sticking off my chest.  I guessed 6-7 inches.  So we planned for a wooden box that was 8"x8".  In the center my Dad tapped a steel rod that I would sculpt on top of for support.

Some great reference images I nabbed from the web.  As soon as I saw these the pics it suddenly became more detailed than I had in my head.  I got nervous that my sculpting abilities wouldn't be enough to satisfy me.  The original chestburster had tiny little arms too, but ya never see them that well in the movie.  I think they were sculpted into the body like a relief.  I left the arms off though - I thought they cluttered the design plus it woulda been hard...  I used a block of Roma Plastilina that I actually had lying around from years ago.  It's an oil-based clay that's pretty rigid to work with and won't dry out.  It's the only clay I've had experience with (since high school) so I think that's part of my short-comings.  I'm sure there are better options out there, but I knew this clay didn't need to be baked or hardened and that it holds up to plaster.

The initial sculpt.  I basically needed to get the size and shape right more than anything.  Really wanted that profile to work.  Since the clay is so rigid, it was tough to get things perfectly smooth like the Alien's dome.  Even with a little water it was tough to shape.  I had an idea for the toothpick teeth that I thought would work so in the sculpt I needed to define a "mouth guard" strip that the teeth would adhere to.  Unfortunately I didn't exactly define that same "gum strip" on the lower jaw.  I think I musta been scared to mess with the lip/jaw/mouth at that point in order to craft a level for the lower teeth to stick to.  Then towards the base I just tore off some hunks of clay and smeared/flattened them out for the fleshy base.

Sizing up the tooth pick teeth.

The gorey chest-hole was one of the funnest parts. Some fleshy clay flaps and rolled out clay tendrils for guts.  The imprecision is what made it so fun.  To make it nice 'n' tidy for the plaster I cut away the clay leaving a quarter-inch lip around the base.  This will give it some heft to punch holes through for mounting.

I was pretty "meh" about the actual alien sculpting, but I figured the paint and blood would make up for it in the end.  "We'll fix it in post!"  At my folks' house we sprayed down the clay with a "mold release (which is why it looks shiny) and attached the sides of the box.  We figured the mold release would keep the plaster from sticking to the clay.  The clay gets manhandled/destroyed when removing it from the mold, but we thought a release might make it a bit easier at least.  Ready for plaster.

We got a 25 bag of plaster of paris from Home Depot.  It seemed like waaaaaay more than we needed, but it's cheap and this way we wouldn't run into the more serious problem of not having enough as sets up.  Plaster is mixed with 2 parts water to one part powder mix -- that's what the two buckets are for.  When the water is added it starts a chemical reaction to harden so you need to work/pour fast.  You can't slow it down or dilute by adding more water - the stuff will harden under water once the reaction begins.

You can see the pour kinda sloshed up on to his dome a bit.  I was kinda worried about that when the other half got poured on top.  Such a thin thing would snap off and create a gash in the top when the latex gets poured but in the end it was okay.  There's also some little drips that splashed and created little dimple on the other side.  I figured the blood and paint would cover those opposed to trying to scrape them off.

Once half was poured, I quickly stuck in four rubber balls making sure they sunk in about half way.  Then pulled 'em out to let the first half harden.  When the second half is poured, it'll fill in the cups and create a four "keys" for which to line up the two halves perfectly.  Or so we hoped...

 Since plaster hardens so fast, we gave it a good couple hours before pouring the next half.  BUT, in hindsight I think we shoulda let this baby cure overnight because it was difficult to separate the two halves.  For each half we poured we also needed to tap on the sides with a hammer to knock out any air bubbles that might be caught between the sculpt and the plaster.  Thus all these little bubbles on the top.

A 25lb. bag of plaster filled a 8"x8"x8" box perfectly.  I was completely surprised.

Scrawled in for posterity initially - but the the mold proved to be a one-time use so we just pitched it.  A very limited release...

The next day we dismantled the wooden box and exposed the plaster cast.  Here you can see half of the mold once we had it all apart.  Separating was the biggest problem we faced as the two sides fused together a bit.  Plaster doesn't really stick to things as it hardens.  It's not like glue, but I suspect we didn't let the first half cure long enough and the moisture was enough to continue the bonding for the when the other side was poured on top.  In addition to that, we knew the clay sculpt had many undercuts and deep nooks and wells in the gorey base that the paster would seep into and harden; making it very difficult to separate.  We knew that, but we didn't anticipate the plaster joining both halves.  We delicately chiseled between the two halves slowly prying them apart - the process was tense.  Eventually we got the halves apart and you can see all the damage we did to the edge.  Fortunately the Alien itself wasn't chipped or damaged.  I think the rubber ball keys were part of the problem too.  You can see they didn't work at all and in fact they probably just provided more surface area for the second plaster pour to cling to.  The good thing is, we didn't really need the keys in the end.  All the chisel damage inadvertently created it's own key between the two sides.

Here's a shot of the sculpt after the plaster halves were pulled from it.  The fleshy parts are a bit mangled and some plaster chipped off in the process.

Here are the two sides lined up looking into the hollow cavity where the sculpt used to be.  Kinda looks like some H.R. Giger art...  Things lined up pretty well and the seam didn't look too damaged from what we could tell.  All those little pockets and holes are the inverted flesh flaps and gory bits from the clay.  When we separated the halves, this is what the clay was hanging on to.  You can see bits of gray clay still stuck in the plaster.  I cleaned out as much as I could with dental-like picks. 

Next step was the latex.  I bought a 16 oz. jar of mask maker's liquid latex from Blick and we filled 'er up.  With the two halves together, we used a ratcheted strap to keep it secure.  I needed a blob of clay on the right side to make a dam where there was some damage from the separation.  Liquid latex is stinky stuff, but it's pretty cool.  It cures with exposure to air and while its obviously very flexible, it's also very strong and tear resistant.  So the idea is to fill it up completely to make a good "skin", then...

...drain it.  Here we have it propped upside down over a bowl to let all the latex drain out.  We let that cure for a little while (just touching it to see how dry it is) then we filled it up and and drained it again to skin up another layer.  We figured we'd leave it draining like this for a full day.  Any excess latex might collect at the base which was preferable opposed to the tip of the noggin.

We could only really see the exposed base to know if it was dry enough, but it passed the poke test so we started to separate the mold.  Again kinda tricky because all the undercuts of the latex base want to cling to the plaster.  In fact, in some areas the latex formed loops around plater bits so I had to break away bits to get it free.  Which is why we just discarded the mold when we were done.

Here you can see some of the detail in the base.  It doesn't look like much thanks to my sculpt, but I was pretty surprised that so much detail was retained when making a copy of a copy of a copy.  My fingerprints in the clay even showed up in some areas!  You can see bits of clay and plaster that had to give away through out the process.  I picked all that junk out.

The mouth is just a small slit of an opening, but I'm happy it was retained.

Popped out.  You can see some excess "flash" the latex made around the seam.  Probably because the mold wasn't precise and airtight and that was the area where some plaster spilled over on the dome.  You might see this kinda stuff on model kits though.  Above my thumb you can see some little dimples/bumps.  Those were air bubbles that we didn't knock out.  Eh, I thought they looked like any ol' natural disfiguration ya might find on a snake-like creature that births from your chest...  Also too, you can see the base is more yellow in color.  That's because the base was most exposed to air and cured the fastest.  The Alien head, for example, was down in the depths of the mold with little air getting to it while it drained.  Fortunately it was cured enough when pried apart the mold.

After some overnight curing, I used a dremel to file down the latex flash and I trimmed away the mouth a bit.  Kinda tricky because the dremel just wants to grab and tug at a rubbery skin when I just want to sand it down/away.  And an exact-o wasn't any easier trying to cut such a flexible and strong material.

In these two pics I painted some extra latex directly onto the creature.  I kinda just wanted to patch over some rough parts/holes and maybe hid the seam a bit more on the topside.  I think the drippy brush strokes looked pretty cool, like blood or mucus, but it kinda got lost when the paint started layering on.

After the latex dried again it was time for paint.  I asked a couple different folks at Blick what type of paint they would recommend for painting latex but they seemed stumped.  I started with acrylics (the little bottles ya see there) remembering back to high school and thinking there was some flexibility in them.  And you can see I have a scrap piece of latex that I was testing paint on in the lower left corner.  When I researched it online a lot of folks mentioned various airbrushing techniques but I wasn't about to invest in a compressor...  

Here's the bloody base in acrylics.  I thought it looked great when the watery paint pooled up in areas and generally made it look wet.  However I came to learn that acrylics were not a good choice.  Once this dried I could see the base was cracking in areas where I'd try to bend it.  And too, I thinned out the acrylics to get an initial wash of color first.  A think fleshy color to start, then built up different consistencies of red - but that weak, diluted mix probably allowed it to crack more easily.

I was getting a little concerned with the acrylics so another trip to Blink and I found some great paints called "Liquitex" which proudly stated that they were water-resistent and flexible when dry.  Perfect.  I started re-painting the base and spattering with with "blood" in my bathtub (to be replaced eventually).

The teeth are in place too.  The tooth pick tips were spray-painted silver since the Alien creatures have what appears to be metal teeth.  I dripped some Krazy glue on the "mouth guard ledge" and delicately held each tooth in place with a pair of tweezers.  It was a mess and no matter how still you think you can hold your hand, ya can't.  The teeth were so light and the glue was so tacky that it felt like static electricity was pulling this tiny wooden tooth in a direction it wasn't supposed to go.  Eventually they all settled in as best I could and I added another coat of latex over the top teeth just to reinforce them more.

I mixed a few different reds (dark and light) so that helped keeping it from looking too flat, but I really like how paint would pool up in the valleys and look wet and shiny!

When the paint was dry we punched a few holes in the outside flange so I could string it up to my chest.  My Dad had a custom made punch set that cut through the latex with a few twists and a hammer smack.  Using some spare shoelaces, it all proved stable enough for an initial test.

Needs more blood!  My sis had a bottle of fake Halloween blood that I used for more gory details.  Again with the shiny wet base...  This fake blood concoction really helped I thought.  Getting in all the cracks and just adding another deeper red to the mix.  When it dried it kinda cracked up in some areas, but it looked cool.  I had a plan to seal it all with a clear varnish in the end so I wasn't too worried about it deteriorating.

With the first fake blood pass drying, I worked on the shirt.  I wore the shirt and just guessed at the relative height to make the incision, figuring I could always tear it more when I stuffed the Alien through. Then more splatter work with the fake blood in the bathtub.  It's really hard to control splatter, but more than that, the fake blood was so thick that it didn't flick off the brush bristles so well.  Eh, I got enough I guess.  I also just soaked the brush and dabbed at the top letting the excess run off and drip.  PRO TIP: a Whole Foods bag made for a great shield underneath the shirt to prevent blood from soaking onto the back.  It's the right size to fit under a shirt, and it has handles for hanging!

With the shirt drying, time for more blood!  Another flick and dribble pass on the Alien itself.  Every step of the way I was nervous something would take a wrong turn.  I really wanted more blood though - like it was soaked in it since it came out of my chest.  I felt like I was getting carried away and it's important to see some part of fleshy yellow Alien.  Any more felt like a gamble.

First dress rehersal.

Eh...I wasn't completely sold on my first blood splatter.  The blood was drying kinda funny around the edges and I thought I might be able to do something better/different with a second go.  So I did another shirt, but it turns out that I liked my first attempt more after I put a second coat of drippings on it.  First is on the right, second try on the left.

On Saturday night I laced it up for a party.  While it was completely stable I was still able to maintain mobility, it did affect my posture and neck.  I felt the need to stand up straight with my chest out and with that shoelace around my neck I felt hindered to turn my head.  It wore off quickly though - just a weird side affect.  This is EXACTLY what it must be like to wear a bra...


I did apply a couple quick coats of a flexible Liquitex varnish for high gloss.  It helped the whole thing look shinier/wetter than without it.  I think the "gore-hole" turned out the best and was the most fun to sculpt and paint since anything goes.  Kinda wish some of the pics were bigger/better, but I'm glad I could at least share the process.  Might add a few more from the party later on.  And I'll bring it on Halloween for friends at work to see up close.


PS - thanks to my Dad for helping out with this scatter-brained Halloween plan!