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Project 2:

Prototyping an object for slip casting

100 points

Begin date: September 15th, 2021

Due date: October 18th, 2021


For this project, you will use the skills you learned during your last assignment involving plaster mixing and some of the basic properties of clay to design a vessel.  You will sculpt an object in clay using two(+) wooden profiles to produce your form with the intention of making a one-part plaster mold of that shape.  Using this plaster mold, you can begin experimenting with liquid clay called “casting slip” to produce multiples of the same form.  


This assignment involves design ideation so you will have an opportunity to sketch out the shapes that interest you to better understand the nature of what it is you’re making before doing so.  Please spend time with these and be as intentional as you can in the way your form follows function.  You will be asked to explain how your design contributes to its specific function.  


***You have four weeks to work on this assignment so please use that time wisely.  Be ambitious.  Ask questions.  Push yourself to make something challenging.   



  • Make X10 drawings of shapes that interest you and focus on the top and bottom profile along with the side profile.  You may experiment with cutting out shapes for the three profiles of your design (Top, Bottom, and the Side) however, you must have X10 well thought out drawings that describe what you’re going to make and why.    

  • Make your prototype based on the demo given in class (YOU WILL NEED TO GAIN APPROVAL FROM YOUR INSTRUCTOR BEFORE MOVING FORWARD)

  • Designs need to incorporate dimensionality - flat surfaces will be discouraged

  • Make X5 of the object you design

  • Your object should be an open form that lends itself well to the one part mold making process.  - this means that you will need to be aware of creating undercuts in your shape.  

  • The nature of the shape is up to you however, you must have an idea in mind for its purpose before beginning to work.  The shape of your design should create an ergonomic experience for the user that speaks of its purpose based on the form you choose.   

  • Decorative elements including glaze or slip coloration will be important - all work must be glazed - I encourage you to experiment with coloring the slip you’re using for casting.  

  • Your  object should be no smaller than 2’ at the base and can be anywhere up to 12” in diameter on the top profile.

  • Your object should be between 4-7” tall unless you gain permission to work outside those parameters.  

  • You will need to time your castings to maintain uniform thickness between castings (20-25 minutes is usually perfect - set a timer!)

  • Forms can be as simple or as complex as you decide - just make sure there is a reason relating back to what that vessel is used for that connects to the design you come up with.  

  • Work will need to be clean and polished - in other words, there should not be any rough edges and your surface treatment should be intentional (use a rib and a sponge to smooth out your work, you can also burnish it (we’ll talk about this too))


You will be graded on:​

1. Sketchbook ideas (possible 5)

Create a wooden form that  promotes a challenging shape..  Avoid flat or round walls. (possible 20)

2. Problem solving design issues and your ability to talk about your intentions/results using the ceramic lexicon (possible 20)

3. Displayed understanding of undercuts (possible 10)

4. Make one clean (without sharp edges, correct thickness, correct plaster:water ratios) mold of one object (possible 15)

5. Make X5 successful (true to form) castings of that object (possible 20)

- Keep in mind that people will be handling the objects you make.  Make sure to clean the rim, feet, and planer surfaces - they should be smooth/soft/able to be handled or used without being injured - no sharp edges.

- All castings need to be uniform in thickness - this means that you may not end up using your first couple of castings until you develop a method of making that produces high quality castings (figure out your timing).

6. Add decorative elements (possible 10)

- - 

Steps involved:


  • Make X10 Sketches - Think about what the rim and foot of your form should look like

  • Using the paper folding technique, create your top and bottom profile and outline with pencil (the graphite will need to transfer to the mirrored surface on the template you’re making)

  • Cut that shape out with scissors - make sure you clip the very tip of the sheet of paper you’re using - this will help you create a center point on the wooden form you’re going to make.

  • Tape this shape to a piece of hardboard along all edges

  • Cut out the outside form using the bandsaw

  • Repeat this process for the inside form as well (this will be your “Foot”)

  • Decide how tall your object will be and cut X2 1”X2”s to that length.  You will need to join these so they are flush using a brad nailer (safety glasses!!!!!)

  • Draw your center line across the hardboard profiles 

  • Line up the corners of your (now 2”X2”) stilt and dap a dime sized amount of glue onto the surface before attaching.

  • Use a brad nailer to attach

  • Repeat for the second side

  • Now that you have your “Armerature” made (this will delineate the limit of where clay can move), you can start pushing clay into the center area - Do this until the clay is packed tightly with as few air pockets as possible.  (you can use your plaster clay to make this part of the project)

  • Once your clay exceeds the profiles of your form, begin screeding along the edge of those shapes, creating your clay form.  

  • This may take quite a few passes - remember that the form you make will be your master copy.  Any mistakes you make in this will be perpetuated into the following castings.  

  • Clean this up using a sponge or your fingers

  • Set up coddle boards and pour plaster mixed to a 70g water:100g plaster powder ratio

  • Allow time to set and demold your prototype. 

  • Plaster will need a week or so to dry completely - it must not be cold when you begin pouring slip into it - all water must be completely evacuated

  • Pour slip and wait 20-25 minutes

  • Pour out the remainder of what’s left back ionto the original container

  • Wait another 30 minutes or so or until you can see a separation between the clay walls and the plaster mold

  • Invert and allow to gently fall/slide out

  • Your work will be extremely fragile in this state so you must allow it to dry (an hour or two or three) before moving it again.  

  • When it’s leather hard, sometimes bone dry, you can clean up your work with a sponge.  

  • Any joining from object to object should happen while the clay is in it’s leather hard drying phase.

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