Mesa Arts Center
Introduction to Glass Casting Fall 2007
Joshua Dopp Instructor
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3rd
project – Oct.
4, 2007
Advanced Mold Making
For this project we will be using clay again. I encourage you to bring your ideas and projects to class. We will discuss ways to make your projects a reality. To help you decide how to proceed lets review a few of the limitations.
We will have to talk with the other class to see how long we can stay in the kiln. This will limit the thickness and or thick to thin complexity. Also, because there are ten students we have a certain amount of space with which to fill the Kiln. (I don’t think this will be a problem though.) Another Issue with the kiln is its height. There is approximately 11” interior height space. I would recommend keeping your model no higher then 10”. The next issue, which we will have to discuss as a group, is the type of glass we want to use. Which will determine the annealing schedule. It may be possible to use differing types of glass in the same firing if we widen the annealing point spectrum. Time is always a limitation. I would like to make our molds on the 11th and get them in to the kiln.
For this project I want to discuss how to make larger scale molds from more complex clay models with undercuts. Inparticular, by pouring layers of investment material, which can be pulled apart to allow the clay to be dug out. The layers should be no thinner than an inch because they are fragile. Making the layers of the mold requiers care while pouring. The plaster should not get onto the model at all, above the first and susequent layers. By using your hand or some type of board on which to pour and protect the model you can keep the model clean. Also be careful not to bumb the mold once you have poured the layer to the desired height as that will result in the plaster splashing up the side of your model. Before you pour a freshly mixed batch of investment shake or vibrate the bucket to get bubbles out. This work needs to be done quickly and should not be to thick as to the fact that it will need to be flowing freely to get all the desired details of your model. After the layer cures, (15 mins or so) dimples or keys should be carved and a thin layer of vasaline should be brushed over the entire investment surface. This will allow the layers to come apart easily and to go back together correctly. One thing you have to be aware of is that you will get a line of flashing at that seam. This can be cold worked away later but if you think about how to incorporate a line of flashing into your design that would be good too.
“The enemy of art is the absence of limitations.” Orson Welles
I found fiberglass flakes at Ball Consulting Ltd. They call them E-Glass fiber flakes and sell them in ten pound bags
My friend Susan has some Gaffer glass, which she is willing to sell us. Here is a lit of the glass and its price. We will need to add $7.00/kilo additionally to cover the shipping cost. Attached is an annealing schedule sheet to look at.
G272 Hyacinth 4.45 Kgs big chunks $ 17.05 a Kilo
G253 Steel Blue 5 Kgs frit $ 13.75 a Kilo
G254 Lagoon 4.77 Kgs oval billets $ 15.70 a Kilo
G278 Rhubarb 9.15 Kgs cut up pieces $ 18.15 a Kilo
G242 Yellow 7.64 Kgs cut up pieces $ 13.75 a Kilo
G220 Apricot 6.32 Kgs cut up pieces $ 18.15 a Kilo
G279 Semillon 9.82 Kgs oval billet $ 17.05 a Kilo
G263 Lime Green 6.23 Kgs oval billets $ 15.70 a Kilo
Multi-Green Orange 5 Kgs cut up pieces $ 17.00 a Kilo
Also to be added is $ 7.00/ per kilo for shipping costs. Here is a link
to the Gaffer color page
Here is a web page that has a calculator for converting volume into exact weight of glass needed.
Please remember to bring or leave at MAC all of the casting projects until I have had a chance to photograph them. I greatly appreciate your help.
Firing Schedule: Advanced Mold Making
Start Date: 10.18.07P
Finish Date: 10.25.07A
| Ramp (deg F / hour) | Set Point (Farenheit) | Hold (minutes) |
| Full | 300deg | 180 |
| 42deg | 1000deg | 0 |
| Full | 1550deg | 180 |
| Full | 1250deg | 0 |
| 96deg | 960deg | 480 |
| 30deg | 860deg | 480 |
| 12deg | 600deg | 480 |
| 12deg | 400deg | 480 |
| 12deg | 200deg | 480 |
| 12deg | 150deg | 240 |
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