This week I thought I would do something a little different…
Zilla and I are still working from home and amidst moulding tasks for the production, I have been continuing to work on my personal project, my little self portrait stop-motion puppet. This week Zilla taught me how to make a stone mould for my character, and as my personal project is just that, it means I can share lots of photos. So I thought, why not document the whole process and give those interested a little how-to!
So here goes…
The Novice* Mould-Makers guide to: MAKING A STONE MOULD!
*I am still learning, so do not take anything I say as gospel. I do however have an excellent teacher in the highly experienced Mattzilla Duron.
Firstly, why stone? Well there are pro’s and cons to creating moulds out of stone. Pros? It is non-toxic and affordable (big pros). Cons? It is not as durable as other materials such as urethane or silicone, but it really depends on your moulds purpose as well as your resources!
Step 1: Spray your sculpt with Crystal Clear
This product is an acrylic coating that helps to protect your sculpt from little nicks, bumps and bruises. You are simply giving your sculpt a little armour to help it endure the mould making process. Make sure to do this outdoors or in a ventilated space with correct PPE. Give it about 20 minutes to off-gas before you take it back inside.
Step 2: Mark your half way line
Exactly as it sounds, draw a line using a marker all the way around your sculpt. This is a guide for you to build up your lay up.
Step 3: Begin your layup
Before starting, find a flat piece of wood to build your layup on. Roll out a base of clay. For this project I used water based clay. You want you base to be about 1.5inches thick, and with plenty of space around your sculpt. Once you have your base rolled out, place your sculpt on top and begin building up the clay to that half way line. Be careful not to damage the sculpt, I really struggled with this and my fingernails nicked my sculpt several times. Don’t stress too much though, you can neaten up the sculpt later. Once you have built up the clay to that half way line, try to make the whole thing flat and neat (I found this the most challenging part). It is also advisable to make your puppet lay as flat as possible. In my case, her hands needed to be pushed back… I basically had to break her wrists to make them sit flat in the clay up. I cleaned up the sculpt afterwards.
Step 4: Add keys to layup
Once happy with your build up around the puppet, and everything is looking flat and neat (or as neat as you can muster without losing your sanity in my case), it is time to add your keys. Keys are like 3D puzzle pieces that help lock your mould together. Keys come in all different shapes and sizes, but for this mould, I created half hexagon keys using the same water based clay.
Step 5: Box it up
Using foam core, create your box. You want the height of your box to be about 1.5inches above the highest point of your mould. Measure everything out, and cut the foam core lightly with a Stanley knife/ box cutter, just enough to snap it without breaking the whole piece off. You want to line the inside of the box with clear tape to prevent your mould sticking to the box. Then use a hot glue gun to glue your box on to your wooden base.
Step 6: Release it
Use a release agent, in this case we used Ease Release 200. This is where mould making is like baking… spraying on the release is like greasing your cake pan. You only need to do a light spray. Make sure to do this outdoors, or in a well ventilated space with correct PPE. Give the release spray about 20minutes to off-gas.
Step 7: Mix your stone
We are using Gypsum cement. It comes in big bags in powdered form, like plaster does. Plaster moulds can be great for one-use moulds, but stone is much stronger. Mix your stone with water, to a syrup like consistency. I do not have a recipe for this, but it is easy enough to add a little more stone or water if your consistency is off.
Step 8: Paint it on
Begin by painting on a thin layer in any detailed sections with a paintbrush. Continue adding more material and build up the layers on your sculpt, making sure to cover all the lay up and also travel up the sides of the walls. The material will begin to cure and thicken as you work, so you can build up the material over the sculpt and layup. Do not completely fill the box.
Step 9: Hessian/ Burlap layer
Wait for your material to cure to a point where if you touch it with your finger, it will leave an imprint, but you won’t have material on your finger. While you wait, cut up some strips of hessian/burlap fabric. Once ready, paint on a thin layer of stone onto your mould, then add a strip of burlap, paint stone over this and continue in a papier mache fashion. You want about 3 layers of burlap in the middle of your mould. This technique makes your mould stronger, and less likely to break. It also makes it much easier to repair your mould if it did break as opposed to if the burlap was not there.
Step 10: Final layer
Again, wait for the material to cure to the point you can leave an imprint with your finger. Then paint/ pour in the remaining material till your box is full. If your material has cured in the bucket, you will need to mix more material. This final layer can be a thicker consistency. Do not add more water or stone to your existing batch as this will not work!
Step 11: Leave your mould to set.
CUP OF TEA TIME! To check that it is ready, touch it with your hand. If it is warm, it is not ready. Once it is cool it is ready to be removed and cleaned.
Step 12: Clean your first part
The first thing you need to do is to remove the mould and box from the wooden base. If you are like me and went to town with the hot glue then this is a task! I used a heat gun to melt the hot glue a little and pried it off! Then flip it over and remove the clay. You can use loop tools to scrape away and/ or a screwdriver or other prying implement to jimmy it up at the sides. The latter worked a treat for me! Then you can clean any excess water clay using a paint brush and water. Then if you like, remove your box (keep it to the side) and spray away excess.
Step 13: Tidy the edges.
Using a plaster scraper or a knife, scrape away any sharp edges on your mould. Neaten up your corners etc.
Now you have completed the first part of your mould. CELEBRATE!
Step 14: Create prosthetic edge (and in turn pry points)
First, use a pencil to mark out your prosthetic edge (Zilla helped me with this). The purpose of the prosthetic edge is to create the smallest seam line around your puppet. When material seeps into the gap between your two mould parts, you end up with a seam of material that must be cleaned up so it is best to use a prosthetic edge to reduce that seam width. This prosthetic edge also creates your pry points which you use to pry open your mould. Roll out some clay to about half a centimetre thick and begin to cut out shapes to place on to your mould. Gradually piece together the puzzle.
Step 15: Box it up
Put your box back around your piece. For this character I need the wall to connect right up to the feet. This will allow me to include my armature in the casting process later.
Step 16: Release it. Repeat Step 6.
Step 17: Vaseline the cured stone
Sometimes releasing the stone is not enough. Stone is porous? and can stick to itself, so the vaseline is a little insurance.
Step 18: Repeat steps 7 - 11
Step 19: Clean up
Now this step can happen now or after you create your foot plate. I did it in this order… well, because I did. So I removed the clay prosthetic edge. And cleaned the second part of my mould in the same way outlined in steps 12 & 13
Now you have completed the first two parts of your mould, it is time to create the foot plate.
Step 19: Tidy up base
The purpose of the foot plate, is so that the material does not escape out the bottom of the mould, while also allowing you to include your armature when casting (we will get in to this when I get in to casting!). You want your mould to be flat where it meets the bottom of the feet. For me, mine was a little off due to a slightly loose wall and material escaping down there! So I used the plaster scraper to neaten that up.
Step 20: Create keys and pry points
For these keys, I simple used a large drill bit and drilled 5 very shallow holes in to the base of my mould around the feet. The pry points (where we will be able to pry our mould open) should be at least the size that you could get a screw driver in there. Again I created mine as half hexagons.
Step 21: Vaseline on dry stone
Repeat step 17. I did not release this part as Zilla thought it was unessecary.
Step 22: Repeat Steps 7-11
This time, I did not have a box around my section so was simply careful to build up the layers on the base, without letting anything drip down the sides (or cleaning it up when it did).
Step 23: Separate pieces and clean!
Like before, tidy up using a knife and a plaster scraper, or sand paper. Give everything a good tidy and a good clean.
Your mould is now complete! CELEBRATE!!
Mine is certainly not perfect. There are lots of things that could be improved, but I gave it my PB and I am very happy with it for my first attempt! You can always use sand paper to sand out any little imperfections, eg. where I made a few unsightly nicks on my puppets thigh. There are also ways to repair your puppet once it is cast, which Zilla will teach me in due course! I did learn how to remove seam lines from a silicone cast in Week 7 if you feel like backtracking for those who are just tuning in.
So next week, I will build my simple armature and cast my puppet, using soft expanding foam and a silicone skin. I will document everything again and hopefully give you another how-to post this time next week!
It has been a great week in our home studio. I have learned a lot and am continuing to grow as an artist.
Till next time.
