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Spruing 101

How to sprue correctly for clean and accurate injections.

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  • 1

    Use the Right Materials.

    We recommend using our premeasured Sprue Wax for ease and precision when spruing. Use the TCS 0.5 gauge Sprue Wax (5025-01) and the TCS 9.5 Sprue Wax (5027-01).

  • 2

    Place Your Model Correctly.

    Before you begin spruing, pay close attention to the position of the model on the flask. Leave no less than approximately 1.5 cm of separation between the saddles and the bottom of the flask. Then, check that the model is leveled to the flask (not too high & not too low).

  • 3

    Use the TCS 9.5 Sprue Wax.

    Place a piece of the 9.5 Sprue Wax (5027-01) at the opening of the flask. Its diameter is measured to perfectly fit the opening of the flask and prevent unwanted plaster from sticking to it, thus prolonging the life span of your flask. Additionally, using the 9.5 Sprue Wax allows for a clean injections and a precise sprue connection. Note: one piece of the 9.5 Sprue Wax yields approx. 10 injections.

  • 4

    Use the 0.5 Gauge Sprue Wax.

    Use two to three 0.5 gauge Sprue Wax (5025-01) pieces to connect the model to the 9.5 Sprue Wax. Sprues should be 0.5 gauge and placed at the far end of the partial where there is a thinner waxed area. To get the best angle, visualize the flow and path that the material will follow. Do not place the sprues right underneath the teeth as this may cause bubbles. Optional: flatten the sprues a little with your fingers, this will help the material flow easily and prevent bubbles.

  • 5

    Use 2 to 3 Sprues.

    Using more than two or three sprues will slow down the flow of the material, thus increasing the chance of bubbles and/or a miscast. Using two sprues is more than enough when spruing for partial dentures , but depending on the case, adding a third sprue down the middle is also okay. For Karadent™ full dentures using three sprues is always recommended.

  • 6

    Connecting Your Sprues Correctly.

    The connection of the sprues to model should always be very thin. Avoid adding extra wax as this will make the connection too thick and may lead to bubbles. Instead, use a hot spatula to melt and adhere the sprues to the model.



Follow these tips on what to do when spruing.
  • Use TCS Sprue Wax
  • Level the model to the flask.
  • Position the model with at least 1.5 cm of separation from the bottom of the flask.
  • Only use 2-3 sprues for partial dentures.
  • Use 3 sprues for Karadent™ full dentures.
  • Position the sprues at the far end of the partial in the thinner waxed area.
  • Connect the sprues to the model with a hot spatula without adding too much wax.


Follow these tips on what NOT to do when spruing.
  • Don't make your own sprues.
  • Don't place the model touching the bottom of the flask.
  • Don't use more than 3 sprues.
  • Don't place the sprues too close or behind the teeth.
  • Don't use thick sprues.
  • Don't use too much wax when connecting the sprues to the model.

Spruing Examples

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