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zaterdag 9 juli 2016

Face casting

In a few months, it's time for Elf Fantasy Fair again! The costume I have in mind requires a mask. More specifically, a rigid, skull-shaped mask. To make sure it fits comfortably on my head, I made a cast of my face, wich I will use for sculpting the mask on.
Making a face cast isn't that easy. You can't do it by yourself, so I called in some help. My wife, her mom and stepdad and one of our friends were glad to help me. And we got the entire process on video!

To make a cast of a body part, you can use either silicone or alginate. Alginate is much cheaper than silicone, but an alginate mold dries out quickly and isn't permanent. Immediately after molding, you have to make a plaster cast, before the mold dries out, and after that, it's thrown away. So, here's the stuff you need:
  • Alginate (I used Smooth On Alja Safe Acrobat, a fibre reinforced alginate)
  • Plaster bandages
  • Vaseline
  • Gloves
  • Plaster
  • Clay
Alginate is a powder derived from seaweed. It's mixed with water to make a slurry that sets into a rubbery consistency. Pure alginate is quite runny and not easy to use for making a cast of a face, the fibre reinforced type I used is designed especially for use on vertical surfaces.

The first thing I did was drawing an outline for the alginate on my face using a sharpie, and then I greased up my entire face using vaseline. Alginate releases from skin quite easily, but eyebrows or other facial hair need to be protected or you risk getting the alginate stuck to your face. I have a short beard, wich wasn't really a problem. A swimming cap is very useful to protect your hair, but since I'm bald that wasn't needed!
Before we mixed a batch of alginate, we cut a roll of plaster bandage into 30 cm strips so everything was ready. Keep in mind to wear clothes that you don't mind getting dirty (they will no matter how careful you are)! I used a large trash bag with some holes cut in it to protect my clothes.
And one very important thing: make sure you have a comfortable chair! I sat on a regular chair, and I had to tilt my head back the entire time. Towards the end, my neck started to hurt quite a bit! Some sort of beach chair would have been a lot better.

The procedure
First, your entire face except your nostrils is covered in alginate. The powder is mixed at a one to one ratio by volume with water. As soon as it's mixed, the clock starts ticking! The Alja Safe Acrobat sets very fast, it starts thickening after five minutes. I had mixed way too much, and we had to throw some away. It's better to mix up small batches.
The most challenging part is the nose, because the nostrils have to be kept open so you can breathe. Don't put straws up your nose, that's way too uncomfortable. I used the back of a sharpie to block one nostril at a time while my crew was putting cold goo on my face.
After the alginate has set, it needs to be reinforced. Alginate by itself is very flexible and tears easily, so it needs a support shell. This is easily done using plaster bandages. Simply dip them in water, and build up a plaster shell over the alginate. It takes about fifteen minutes for these to fully harden, after wich the mold can be removed.

After the plaster has hardened, it's time to remove the mold from your face. Some tutorials tell you to remove the plaster and alginate separately, other recommend removing them together. I removed them together so the alginate was supported all the time.
We carefully peeled the edges off my face first, while I used my facial muscles to slowly loosen it from the inside. Take your time for this, you don't want to damage the mold! It works best if you tilt your head forward, support the plaster shell with one hand and use the other to get the mold off your face.
After removing the mold, you first have to plug the nostrils with some clay, and then immediately pour plaster in it. An alginate mold isn't permanent and dries out quite fast. I used Ultracal 30, a mixture of plaster and cement that's very strong and durable. This stuff sets slowly, so you don't have to rush things. At first, I was afraid I didn't mix it right because it took so long to set. It took an hour before it started to thicken, and the next morning, it had set.
After the plaster has set, you remove the alginate and plaster bandage; they can be thrown away now. The plaster casting probably needs some cleaning up around the nose. In my case, there were some minor flaws around my mouth. Because we underestimated how fast the alginate set, we had to tear off a piece and start over again, but it's not really a problem.

donderdag 7 juli 2016

Book cover ornaments

I've this isn't the first time you stumbled upon my blog, you know I have made a few customized sketchbooks. I've got this cool technique to make imitation leather, that's both a lot cheaper and easier than using real leather. If you want to learn about it, check out this post (this was my first book project, wich kinda failed, but it explains the technique nicely and I don't want to explain it again every time, so I just refer to this post).

Another thing I add to almost all of my books is some sort of cover ornament. Corners, symbols, all sorts of stuff. Until now, I always made them out of cardboard or MDF, but these thingies take a lot of time to make, much more than you'd think. Since I sell these books in my Etsy store, I should charge an insane price if I want to take into account the amount of time that goes into making one.
To speed up the process a little bit I decided to make molds of my cover ornaments, so I can just cast them in resin. Also, it makes it easier to make multiple copies of one book and keep my store stocked. Until now, after a book was sold, I had to remove it from the store.
So let's get started! I made some ornaments like I did for my other books, and then made silicone molds from them.

  • MDF scraps (I never throw leftover away, they come in handy for stuff like this)
  • Coping saw, files, sandpaper
  • PVA and cyano acrylate glue
  • Acrylic gesso and paint
  • Sand (more on that later)
  • Foamcore board
  • Hot glue gun and sticks
  • Release spray
  • Molding silicone
Shaping the ornaments
I made four corner ornaments, four clasps for wrapping straps around the back of a book, and an Elder Sign sigil. This involves a lot of cutting, filing and sanding.
MDF doesn't really hold a sharply defined edge very well, especially thin MDF. There's a trick I learned from Bill Doran at Punished Props, though. If you apply cyano acrylate glue to the edge, it becomes very hard and keeps a good edge much better. Use thin glue for this, not the gel type, so it soaks into the fibres. After it has dried, you can sand and file it much better. Oh, and it never hurts to keep a bottle of acetone near when working with super glue. I managed to glue my fingers together on more than one occasion...

I wanted to give the Elder Sign sigil a textured background. I sprinkled coarse sand over it, smoothed it out as much as possible, and then dripped watered down PVA glue over it, soaking the sand with it and glueing it in place.
Before making a mold, I painted all pieces, first in gesso primer and then gray paint, and sanded it between each coat. Painting it makes it easier to spot any flaws.

When my ornaments were ready, I made molds using silicone. There are two kinds of mold making silicone: tin cured and platinum cured. Tin cured is cheaper, but it shrinks a little bit (not much, and usually not really an issue) and has a shorter life span; after a few years, it will start to deteriorate. Platinum cured silicone hardly shrinks, but it is quite sensitive to cure inhibition. Certain kinds of clay, glue and paint prevent it from properly curing. Most of the time, tin cured will do just fine.
The type of mold I made is the simplest type, a flat-backed box one part box mold. To construct the box, I used foamcore board and a hot glue gun. Foamcore is strong enough to build a molding box, but easy to rip apart after the silicone has cured. To make sure no silicone creeps under the ornaments, I glued them to the bottom of the box using PVA glue. And even though it's not strictly necessary for silicone, I applied some mold release spray.

Next, I mixed up some silicone and poured it into the mold boxes. To prevent bubbles (and if you don't have a vacuum degasser chamber), pour it from high enough, so the stream gets stretched out and most of the bubbles pop. It's best to pour it in the corner of the box and let if flow over the items, instead of pouring directly on them.
The next day, the silicone had cured and I liberated the items from the molds. They turned out quite ok, without any visible flaws. I already made a few casts using polyurethane resin, and it works perfectly!