Summer Sourdough Crushed Ice & Water Temp Chart for a Hot 78 Degree (78°F / 26°C) Kitchen — Hand Mixing (75°F Target DDT)
4-factor Desired Dough Temperature (DDT) and 80 cal/g latent heat crushed-ice calculation for hitting 75°F dough in a hot 78°F room.
Heat flows in two directions in a 78°F (25.6°C) kitchen: heat flows from the 78°F flour and levain into the dough, and hand mixing (75°f target ddt) adds +2°F of its own. To land the finished dough on 75°F, the 331g of liquid water must enter at 64°F (17.8°C). Cooling from 74°F tap water down to 64°F means melting 19g of ice into the 350g batch and leaving 331g of liquid water; each gram of ice absorbs 80 cal on melting alone.
- Required Water Temp
- 64°F (17.8°C)To hit 75°F DDT in 78°F room
- 350g Batch Ice Split
- 19g Ice / 331g WBased on 74°F tap water & 80 cal/g latent heat
- Mixer Friction Factor
- +2°FHand Mixing
- Target Final Dough Temp
- 75°F (23.9°C)Locks fermentation clock & protease rate
Batch-Scaled Ice & Water Chart for a 78°F Kitchen (Hand Mixing (75°F Target DDT))
Read the ice column as a direct instruction: weigh that much crushed ice and make up the balance with 74°F tap water.
| Total Water | Calculated Temp | Ice Quantity | Tap Water Quantity | Dough Temp Target |
|---|---|---|---|---|
| [Anchor]: 300g total water | mix at 64°F | substitute 16g ice | keep 284g warm water | friction +2°F absorbed |
| Quarter Batch: 350g total water | mix at 64°F | substitute 19g ice | keep 331g warm water | friction +2°F absorbed |
| Three-Quarter Batch: 500g total water | mix at 64°F | substitute 27g ice | keep 473g warm water | friction +2°F absorbed |
| Half Batch: 250g total water | mix at 64°F | substitute 13g ice | keep 237g warm water | friction +2°F absorbed |
| Double Batch: 400g total water | mix at 64°F | substitute 22g ice | keep 378g warm water | friction +2°F absorbed |
Dynamic Stoichiometric Workbench (64°F (17.8°C))
Test custom loaf weights or alternative fermentation schedules directly against the 19g Ice / 331g W benchmark above.
Baking Sourdough in a Hot 78°F Room: Why You Need 64°F Water (19g Ice)
Friction is the variable bakers forget. Hand Mixing (75°F Target DDT) contributes +2°F, and because that heat is generated inside the dough rather than supplied from the room, it cannot be compensated by simply lowering the water temperature of the flour. It has to be subtracted from the mix water before mixing begins.
Ice quantity and water quantity are not interchangeable views of the same thing. 19g of crushed ice is the solid portion; the 331g of tap water that accompanies it is what actually hydrates the flour. Both numbers must be weighed.
Thermal Control Protocol for Hand Mixing (75°F Target DDT) in a 78°F Room
- Weigh the Full Water Load: For a 350g batch you need 331g of liquid water plus 19g of crushed ice. Set the scale up before you touch the flour.
- Chill the Water: Add the 19g of ice to the 74°F tap water and wait until the melt is complete so the temperature is stable when the flour arrives.
- Mix in Hand Mixing (75°F Target DDT): Combine flour and water, then run the mixer for the full recommended time so the +2°F of mechanical heat is actually generated rather than assumed.
- Confirm 75°F: Probe the finished dough immediately. In a 78 deg F (25.6°C) kitchen the reading should land on 75°F ± 1°F.
Key Baker's Math Questions (Required Water Temp: 64°F (17.8°C))
Can I mix the ice directly into the flour?
Yes, and it is often the better technique. Mixing 19g of crushed ice into the 331g of water and flour together chills the mass faster than adding cold water to warm flour, and the 80 cal/g phase change is fully captured.
Will the dough temperature change if I scale the recipe?
No. The 4-factor equation is a temperature balance, not a mass balance, so doubling the flour and water keeps the same 64°F target — but you must double the ice too, from 19g to 38g.
How much ice do I add to 350g of bread water in a 78°F room (Hand Mixing (75°F Target DDT))?
Replace 19g of water with finely crushed ice and use 331g of 74°F tap water to hit 75°F DDT.