Dental Products & Supplies - Technical Tips, Gypsum Mixing Techniques, ISO Types & Product Information

Technical Tips

Gypsum Mixing Techniques

  • Use room temperature water.
  • Use only water that is drinkable.
  • Always place water in bowl first, then add powder to water slowly and evenly.
  • Let powder soak in water at least 30 seconds while moving bowl around to wet the powder before mixing.
  • HAND MIX using back-and-forth strokes, occasionally turning the bowl and scraping down the sides to incorporate all dry and unmixed material. Do this until a creamy homogeneous mix is achieved. Usually 30 seconds is adequate. MECHANICAL MIXING accelerates the working and setting time of Dental Stones and Plasters. Because mechanical mixers are faster, place powder into the water and stir by hand until all powder is wet, then start mechanical mixer. Mix for a shorter time, 10 to 30 seconds, then hand mix to check for a homogeneous mix. DO NOT OVER MIX.
  • Mixes can be made thicker or thinner by changing the recommended water plus or minus 1cc without significantly changing properties.
  • Cast models can be removed from impressions when the exotherm is completed. This can generally be determined by touch, i.e. when the heat generated after the initial set has subsided.
  • It is important that mixing bowls and other mixing equipment for Dental Gypsum be used ONLY FOR MIXING Dental Gypsum. Other materials such as phosphate Investment or Impression Materials mixed in the same equipment will seriously contaminate and change the properties of the Dental Stones.

Gypsum Product Information

ETI Empire Direct gypsum products are broken down into three major categories. Each has a general use within a specific technical procedure.

  • Dental Stones
  • Die Stones
  • Dental Plasters

Specific products and properties are listed on the back of each box.

Water to Powder Ratios

The water to powder ratio for each product is given in cubic centimeters (or millimeters) water to 100 grams of powder.

Initial Set Time

The initial set time listed in minutes is a standard vicat test. Actual working time will be 2-4 minutes less than the initial setting time.

Packaging and Storage

ETI Empire Direct gypsum products are packaged in 25-pound boxes with a 4 mil plastic bag. This package helps keep the material fresh and more efficient to handle. IMPORTANT: once a package is opened the material is exposed to moisture and proper storage is required. Dental gypsum products are very hydroscopic, therefore it is important to reseal the plastic bag and store it in a dry space at room temperature when not is use.

Caution

It is important that mixing bowls and other mixing equipment for dental gypsum be used only for mixing dental gypsum. Other materials such as phosphate investment or impression materials mixed in the same equipment will seriously contaminate and change the properties of the dental stones.

Also be sure to clean all mixing equipment when you are finished and that no dry gypsum remains in the bowl or on your spatula.

All ETI Empire Direct dental gypsum products are batch controlled and tested. Only the finest raw materials are selected and used. This produces a consistent quality necessary for accurate dental restorations.

If you have any questions or requirements, please call us at 800.451.7778 or send an e-mail to order@etiempiredirect.com

ISO TYPES

ISO Type 1: Dental Plaster, Impression

ISO Type 2: Dental Plaster, Model

ISO Type 3: Dental Stone, Model

ISO Type 4: Dental Stone, Die, High Strength, Low Expansion

ISO Type 5: Dental Stone, Die, High Strength, High Expansion

Repli-Cast™ Tech Tips

Rapid burnout investments are sensitive to variations in mixing time, speed and temperature. To improve casting results, follow the instructions provided with your shipment (you can also download them here) and adjust them as suggested below:

Tight Fit?
  • Increase the liquid concentration. Maximum setting expansion is achieved by using 100% Repli-Castâ„¢ Liquid.
  • Warm the liquid to 25-28° C / 78-82° F.
  • Remove the mold from the ring at 15 minutes and allow it to benchset freely for an additional 5-10 minutes.
  • Increase mix time by 15-30 seconds.
Rough Casting Surface?
  • Make sure your vacuum mixing unit is pulling 27" Hg or more of vacuum.
  • Use a water-based debubblizer.
  • Check the burnout temperature of the oven. Refer to the metal manufacturer's recommendation for burnout temperature.
  • Slightly warm the liquid as a cool or cold mix temperature can produce a rough surface.
  • Increase the mix time by 15-30 seconds.
  • Hold under the vacuum for 30 seconds longer.
  • Replace the mixing bowl every year and the paddle every 2-3 years.
  • Use a dry liner for metal rings.
Molds Cracking or Exploding?
  • Let the mold benchset for a minimum of 15 minutes.
  • Trim off the top glaze on the mold and re-wet or rinse off under tap water.
  • If benchset over 24 hours, trim off the top of the mold and place in a bowl of room temperature water for 2-3 minutes.
  • Place the mold in lower temperature (650° C / 1200° F) preheated oven. Hold for 15 minutes, then heat to desired high temperature.
  • If 100% liquid is needed for proper expansion, mix at a slow speed for 45 seconds, then hold under vacuum with no mixing for 30 seconds.
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