Understanding and Calculating the Friction Factor in Dough Making (Heat Generated During Mixing)
Every time you knead dough, you are generating heat. Whether you are using your hands or a high-powered mixer, the physical energy used to develop gluten creates friction, which directly raises the temperature of your dough. This “extra” heat is known as the Friction Factor (FF). In this article, we’ll break down how to calculate your specific friction factor, so you can account for it when planning your water temperature – ensuring you never miss your target Final Dough Temperature.
What Is the Friction Factor in Dough Making?
In dough making, the Friction Factor is a variable used to calculate the Final Dough Temperature (FDT). It represents the exact amount of heat, measured in degrees (C°/°F), that the dough accumulates during the kneading process.
For example, if you start with ingredients that average 20°C but your dough ends up at 30°C after kneading, your friction factor is 10. You have effectively “added” 10 degrees of heat just through the act of mixing.
What Influences Heat Generation During Kneading?
The amount of heat generated isn’t random; it depends entirely on your specific setup and technique:
- The Kneading Method: Hand kneading generates the least amount of heat because it is slower and gentler. Mechanical mixers, especially home stand mixers, create significant friction against the bowl sides, heating the dough much more/faster.
- Kneading Speed: High-speed mixing generates heat much more aggressively than a slow stir.
- Dough Volume and Bowl Size: The ratio of dough to the size of your bowl affects how much surface area is creating friction.
- Kneading Duration: The longer you knead, the more heat the dough absorbs. A 5-minute knead will have a lower friction factor than a 15-minute knead.
Ultimately, because every baker’s hands, mixer, and kitchen environment are different, your friction factor is unique to you. To accurately control your FDT using the PizzaBlab’s Final Dough Temperature Calculator, you first need to determine what your specific friction factor is.
Typical Friction Factor Values by Mixing Method
Because every kitchen setup is different, the heat generated during mixing will vary. However, there are established “starting ranges” based on the method you use.
Important Note on Units:
The friction factor measures a temperature difference (how many degrees the dough gained) rather than an absolute temperature. Because of this, you cannot use a standard converter.
To convert an absolute temperature from Fahrenheit to Celsius, you would subtract 32, multiply by 5, and divide by 9. However, when converting a temperature difference (like FF), you must exclude the subtraction of 32. Simply multiply the value by 5 and divide by 9.
For example: A friction factor of 10 in Fahrenheit is equivalent to a friction factor of 5.5 in Celsius (10×5/9=5.5).
| Celsius (°C) | Fahrenheit (°F) | |
| Hand Kneading | 1–3 | 2–5 |
| Stand Mixers | 8–16 | 15–30 |
- Hand Kneading: Generally creates very little heat. However, be aware that your work surface acts as a heat sink or a heater. A warm granite countertop will raise your friction factor, while a cold stainless steel table might lower it.
- Stand Mixers: These are heat-generating machines. Factors like high speed, a heavy dough load, or a long mixing time will push your friction factor toward the higher end of the range.
Where to Start: Baseline Starting Values
If you are using PizzaBlab’s FDT Calculator for the first time and haven’t calculated your specific friction factor yet, use these “safe” starting values:
- For Hand Kneading: Start with a value of 2 (for both °C and °F).
- For a Mixer: Start with 12 (°C) or 20 (°F).
While these estimates are a great starting point, the most accurate way to control your FDT is to calculate your own specific friction factor.
How to Calculate Your Specific Friction Factor
While using the general estimates is a good start, calculating your own specific friction factor is the best way to achieve professional results.
The great news – you typically only need to do this once. As long as you keep your equipment, kneading time, and dough quantities relatively consistent, your friction factor will remain the same for every future bake.
The 4-Step Calculation Process
To find your friction factor, you simply need to bake one “test batch” of dough and record the temperatures along the way.
- Measure Before You Mix: Record the temperature of your room (RT), your flour (FT), and your water (WT).
- Knead Normally: Prepare your dough exactly as you usually do (using your hands or your mixer for your standard duration).
- Measure the Finish: Immediately after you stop kneading, measure the internal temperature of the dough. This is your Final Dough Temperature (FDT).
- Solve for FF: Input these four numbers into the formula below.
The Friction Factor Formula
FF = (FDT × 3) − (WT + RT + FT)
Note: If you are using a preferment (like Biga or Poolish), multiply the FDT by 4 and add the preferment temperature to the sum in the second bracket.
A Real-World Example
Let’s look at a typical scenario where a baker wants to find their mixer’s friction factor:
- Room Temp (RT): 22°C (72°F)
- Flour Temp (FT): 22°C (72°F)
- Water Temp (WT): 18°C (64°F)
- Final Dough Temp (FDT): 26°C (79°F)
The Calculation (Celsius):
FF = (26×3) − (18+22+22) = 16
The Calculation (Fahrenheit):
FF = (79×3) − (64+72+72) = 29
The friction factor for this specific mixer and technique is 16 (Celsius) / 29 (Fahrenheit). Now that this baker knows their FF is 16, they can simply plug that number into PizzaBlab’s FDT Calculator every time they bake to get the perfect water temperature instantly.
Summary & Concluding Remarks
Understanding the friction factor allows you to accurately control your final dough temperature. Instead of wondering why your dough ended up too warm or too cold, you now have the exact mathematical tool to account for the heat generated by your specific kneading method.
Key Takeaways
- What It Is:
The Friction Factor (FF) is the amount of heat (in degrees) your dough gains during the kneading process. - Heat Sources:
Friction is caused by the dough rubbing against the bowl or work surface; mixers generate significantly more heat than hand kneading. - Baseline Values:
If you don’t know your FF yet, start with 2 for hand kneading or 12°C / 20°F for a stand mixer. - One-Time Task:
You typically only need to calculate your specific FF once. As long as your process remains the same, your FF will remain consistent. - How to Find It:
You determine your FF by running a “test batch.” You record the temperatures of your room, flour, and water before mixing, then measure the dough at the end to see how much heat was gained. - The End Goal:
Knowing your FF is the final piece of the puzzle for using the PizzaBlab’s FDT Calculator with 100% accuracy.
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