Term
| Explain how plaster is made and its properties |
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Definition
| Plaster is white in color and is cheap because it is not a strong material and it is pourous. It is not strong and it is ground into a powder and heated in an oven with no pressure (calcining) |
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Term
| what does plaster require more water than stone or improved stone? |
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Definition
| because it has irregular particles that have more surface area than stone and improved stone. |
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Term
| what is the chemical name for gypsum |
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Definition
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Term
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Definition
| a replica used to study or observe treatment in progress |
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Term
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Definition
| a replica or more than one tooth made of plaster or stone for diagnostic purposes |
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Term
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Definition
| a single tooth replica used to produce a wax pattern made of metal or ceramic stone. |
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Term
| Explain the process of making stone |
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Definition
| Stone is a strong material and is used for diagnostic purposes. It is made in the calcining process, and heated with pressure. |
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Term
| how much water does stone require? |
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Definition
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Term
| how much water is required for improved stone? |
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Definition
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Term
| what is improved stone ususally used for? |
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Definition
| it is used in a lab setting to fabricate an inlay or crown, so it is very strong, and dyed blue or green. |
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Term
| What is the setting time? |
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Definition
| a 10-15 minute period from the time the material reaches water until it begins to harden. |
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Term
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Definition
| the amount of time it takes for the material to lose its glossy appearance and no longer flows. |
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Term
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Definition
| once the material can not be penetrated with a gilmore needle final and has reached its minimal hardness. |
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Term
| How would you increase the setting time of gypsum? |
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Definition
| Use more water creating a thinner mixture, use cold water to prevent the exothermic reaction from begining, add retarder to the mixture to keep it from hardening and decrease the amount of mixing time. |
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Term
| To decrease the setting time? |
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Definition
| Add less water, that is a warmer temp. to the gypsum, and mix for a longer time. The mixture will be thicker. |
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Term
| What is the proper way to pour up a gypsum model? |
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Definition
| Please the mold on a vibrator and place the mixture so it flows ahead of itself. Do not over vibrate because it can cause air bubbles. |
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