Blood pump
Casting NathanWow, it's been a couple of weeks (three weekends) since my last update. I could have sworn I was going to do weekly posts... ah well, work has been crazy and the weekends not much slower.
Since I last wrote, I received my shipment of silicone, alginate, plastics, and other supplies from Smooth-On; sadly, one work-day later than I needed, so the life casting was delayed to last weekend. More on that later.
Also last weekend we had a massive workshop setup and cleaning event (we call these things "parties" to draw more workers) -- and we got excellent results. In the midst of this chaos, Mohammad, one of our diligent volunteers, used the (shiny new) tubing bender to curve out a half dozen or so tubes for the vortex tunnel. He ran out of raw materials before he ran out of enthusiasm. Minions are great!
Paul, when not building the new stairs to help us get IN to the lab, or shelves to help us store more stuff in the Lab, also started work on the portable "oven" for the vacuum table, very handy.
In my copious free time, I put together a prototype for the large blood pump and tested Andy's small peristaltic pump (which works beautifully). I also whipped up a useful magnetic stirring device to make it easier to formulate new blood and slime recipes (some powders must be continuously stirred while sifting or they clump). The blue LED from the variable-speed computer fan gives the whole thing an eerie mad-science glow that I love, too.
I never did get around to making skull-cap material out of PVA; I'm -sure- it will work, though! Just need to try a dozen or so formulations until one works... maybe next weekend.
Also, last short piece, my dentist (Matthew Carpenter, in Round Rock, great guy) has been providing information and materials support for our dental prosthetic tasks.
The BIG event, that we've been preparing for, was the lifecast of Nathan, who we will then sculpt Demon makeup for. We will transform this nice fellow into a nine foot horror... it will be fun! We will also do the same to _me_ (the price I demand for buying all of the supplies) as a backup, and for my Christmas and Halloween costume. It's my year to win the company contest, after all. Sadly, my own lifecasting won't be done for another couple of weeks, due to schedule constraints.
Beginning Sunday early at the Lab, I put some finishing touches on the magnetic stirrer; kicked around a bit; and started assembling supplies. We were using a number of new things this time -- burlap and raw plaster, a new additive to the silicone to act as a built-in release, and of course, no bald cap.
The bald cap and the burlap instead of medical bandages is due to the offensively expensive nature of these items. Sadly, it turns out that at least one of them (the plaster bandages) is still critical to the success of a good lifecasting shell. But burlap and Hydrostone 105 (10-15 minute set time) can still act as a durable second layer, and they are infinitely cheaper than plaster bandages.
I did a test of the burlap "bandage" and it set up fairly well, and it held the plaster nicely.
I got an ancient tub with remnants of some body double (the silicone I use) and mixed up a small batch to make sure it would set. It did, if a bit sluggishly.
Marla cut a bunch of burlap strips. I organized the table, pre-measured some stuff, fiddled with some minor things. Matt came in around noon and built a scrap box out of scrap wood, a lovely and useful thing. Beth showed up, as did Susan P (the OTHER Susan P), who was to be our photographer today.
Nathan had gotten turned around driving to the Lab, but eventually Susan was able to get him there... but our noon start time was well destroyed by then.
At two-ish, I gave the assembled (restless, cat-like, distracted) crew the long, detailed "this is what we are doing" story, referring to my three pages of notes in the process. Sorry for the tedium! But I like to have a well-informed group.
Of course, Matt and Marla have assisted me on this stuff for _years_ and are great -- I'll be relying on them to do my lifecast later. A lot of the spiel was for Nathan (a complete newcomer, unaware of the torments to come, though we did try to warn him), Beth, and Susan.
That done, we propped Nathan up on a comfy stool, gave him his last chance to drink or pee for the next three or four hours, and then taped cling wrap to his head. Actually, I used spirit gum for some parts, and cloth bandage tape for others.
Since we aren't doing an "art mold" but just a shape (with detailed face/clavical) to act as a base for prosthetic makeup and costume, we weren't worrying about most of the details.
Once he was capped, some trash bags and duct tape made a fetching protective skirt. Of course, the rule at the Lab, especially if I'm working with anything the least bit moist, is to never wear anything you love...
The back shell of burlap soaked in plaster went very well, though the weight of the material made it pull away from the center line we started with -- annoying, but not too bad, since we just reset the center line after the bulk of it had firmed up. However, medical plaster bandages do a much better job of sticking and conforming to the model, so the first layer should be made up of those, with a second layer of burlap/plaster for strength (and cost reduction).
The final aspect of the back shell was to build up a ridge about an inch back from the edge, to act as a back-stop for the front shell (a technique that I decided on just prior to this project) and with keys for rotational alignment. I then used some loose plaster to fill any undercuts around the backstop and keys and to generally firm up anything that looked too dry.
Once the backstop and keys were firm, I took a sharp modeling tool and cleaned the edges, removing texture and giving clean lines to the ridge and edge. Then, a liberal (very liberal, widely applied) layer of petroleum jelly. Yum!
The front frame went in about the same as the back, though we started with bandages based on our recent experience with the burlap. We had just about finished the front frame (and partial shell) when we, and by "we" I mean Nathan, discovered that lifecasting in a 100-degree lab with exothermic materials is not the best way to support life. Heat-induced claustrophobia took over Nathan's brain and we popped the shells off of him in no time. We were at a point, however, that everything was still in good shape.
After cooling Nathan down, we remembered that we had a (newly cleared) air-conditioned office at the back of the Lab. Oops! We moved into there to finish reviving Nathan.
To all of our surprise, Nathan then insisted that we finish the mold. Dubious, we were eventually convinced.
We strapped the shell back onto him, held in place with a loop of duct tape, and then I used one layer of medical plaster bandage to lock the halves together. No worries about having to chisel him out, though, since a single bandage will peel off easily; it has just enough grip to act as a clamp. Needless to say, in the fuss we forgot to re-skirt Nathan. His pants will never be the same.
Our trusty assistants (Marla and Glen by now, Beth had to take her leave) then started mixing up silicones.
Remember that test I did at the beginning of this day? Yeah, well, it appears that storing that one tub of silicone at the lab for a few months did, in fact, kill it—it set all right, it set up almost instantly. Even with the new Hyper-Folic additive, which would normally retard the setting, it was nearly useless.
The 80+ degree temperature in the "chilled" office didn't help, either. These materials say "Store and Use at Room Temperature." Apparently, rooms don't normally reach 110 degrees during the day.
Very aware of the amount of time that Nathan was having to spend in his shell, we threw out that batch of silicone and opened a new one, straight from the mail last week... only to find that it is setting up too fast too!
I didn't notice (at the time) that we had opened a quick-set one. Oops.
So I grabbed my trusty cartridge gun and my last two cartridges (which had been cooking at the lab just like the first, bad, tub we had discarded; I crossed _all_ my fingers on this one, believe you me) and we went back to the old, reliable (if a bit crude) caulking-gun method for the bulk of the silicone.
The details turned out surprisingly good for such an interrupted, heat-damaged process. For this, I have nothing but praise for my trusty assistants, Matt and Marla.
Eventually, we were happy with the silicone and I had thickened a small batch and stuck on a few blocky, blobby keys, and we went straight in to finishing the front shell (even before the keys had set).
The remaining shell was a simple layer of plaster locking the silicone onto the front frame, and it went on quickly and easily.
Then we popped the shells apart, as I marveled at how well my new technique at the edge worked, and pried it all off of Nathan's facial and head hair.
The tiny amount of hair-released silicone we did manage to get onto his face, from that aborted batch, did an amazing job.
Soon, though, I need to do a mix test with this stuff in a new, air-conditioned batch of silicone, to see how it affects the material. I'm feeling a bit dubious about it so far.
And, from now on, I keep all delicate materials at home, and we start all lifecastings in the cold room in the back.
In spite of the excitement, we were done before six, giving us maybe three hours of working time on the model, and we got a mold that will do what we need — provide a base to sculpt the Demon makeup onto.
Success!
I’m currently uploading over 100 megabytes of pictures to Flickr, so I don’t have links for them yet — but look me up as EdwinWiseOne (a person) or for the sets “
Blood Pump” or “
Casting Nathan” to get a glimpse of the exciting life of a haunted house FX team.
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