The motor produces very high torque, which allows it to mix even the largest volumes with ease. The results are optimally and fully reproducible even with the most difficult mixing materials. This is completely independent of the quantity mixed, whether 40g or 1kg.

Both the powerful motor pump and also the ingenious Venturi technology guarantee consistent vacuum levels. But even more important is the absolute value of the vacuum because inadequate vacuum output results in uncontrollable expansion behavior of the materials. Many units in the market do not achieve the minimum requirement for investments of 90 mbar. The Twister units achieve on average 60 mbar and better (the smaller the value the higher the vacuum), so that we can guarantee the required value.

Due to the special geometry of the mixing paddles, the material is optimally mixed where it collects because of the centrifugal force. There are appropriate sizes of mixing bowls for different quantities, so that this effect is always utilized.

Step-by-step guide to mixing dental stone correctly

Proper mixing of dental stone is crucial for the quality of dental models.  Errors in the mixing ratio or technique can lead to porosities, internal stress, or inaccurate casts. Follow these key steps for optimal results:

1. Preparation

• Clean workspace: Dust and contaminants can compromise the quality of the stone.
• Water quality and temperature: Use clean tap water at approximately 20–23 °C (68–73 °F).
• Equalize material temperature: Stone and water should be at similar temperatures to avoid delayed setting reactions.

2. Observe the mixing ratio

• The mixing ratio depends on the product and is usually given as a water-to-powder ratio, e.g.,  100 g of stone to 30 ml of water.
• Accurate weighing is essential – even small deviations can significantly affect flowability and strength.

3. Mixing

• Add water to the mixing bowl first, then slowly sprinkle in the stone.
• Pre-mix manually with a spatula for about 10 seconds to prevent clumping.
• Then mix mechanically, ideally under vacuum, to eliminate air bubbles. Mixing time varies by device and material, typically 30–60 seconds.

4. Processing

• Use the stone immediately after mixing, as the setting process begins quickly.
• Vibration helps remove air bubbles during pouring.
• After pouring, allow the model to set undisturbed and vibration-free.

5. Cleaning

• Clean the mixing bowl and tools immediately after use to prevent material buildup.
• For particularly fast and thorough cleaning, use the GO 2011 speed cleaning agent. It effectively dissolves stone residues while protecting tool surfaces at the same time.
• Avoid aggressive cleaners, as they may damage surfaces.

Recommended equipment for optimal results

For a homogeneous, bubble-free mix, Renfert recommends using vacuum mixing devices such as:

• Twister evolution – For precise and reproducible mixing using a vacuum pump
• Twister venturi – Compact and efficient for smaller labs

These devices ensure consistent texture and minimize air entrapment, significantly improving model quality.