A three-degree kettle comparison
Does 90°C versus 93°C change your experience of the same measured filter recipe?
Protocol only: BrewLab has not performed or measured this comparison. Planned numbers are examples, not results. Taste suggestions are hypotheses; no outcome is guaranteed.
The temperature on a kettle is not the temperature throughout a coffee bed. This protocol changes the chosen kettle setting and keeps preparation as consistent as practical. It records what you observe without claiming to measure the slurry temperature or establish a universal roast rule.
Set up a fair comparison
What you need
One adjustable kettle or an appropriate thermometer, scale, brewer, grinder, matching filters, one coffee and two cups. A thermometer is optional for logging, not permission to handle boiling water carelessly.
The factor you change
Kettle water temperature. A: 90°C kettle setting. B: 93°C kettle setting.
What to keep consistent
Use 20 g coffee, 320 g input water, the same grind, filter rinse, brewer preheating, bloom and pour schedule. Keep the water source and measurement point constant. Check local boiling limits before choosing a target.
| Plan | A | B |
|---|---|---|
| Dry coffee | 20 g | 20 g |
| Input water / espresso yield | 320 g | 320 g |
| Ratio (dose : water or yield) | 1:16 | 1:16 |
| Kettle / machine setpoint note | 90°C | 93°C |
| Grind plan | Your baseline grinder setting | Your baseline grinder setting |
| Duration in recipe template | 180 s — replace with observed time | 180 s — replace with observed time |
These are planned settings. Template durations are editable placeholders, not targets to force or measured results. For espresso the water/yield field means collected espresso; otherwise it means input water.
Setup saves two recipes only, without changing existing recipes, creating brew records or deducting stock. Choose a bean bag and confirm usage separately when recording each brew. Local storage details.
Run the comparison
- Confirm your kettle can achieve both settings within local boiling conditions. If not, skip this numerical protocol rather than treating an unattainable setpoint as a measured value.
- Use the same preheating and filter-rinsing routine for both brews. Record whether the thermometer reading is in the kettle or at another location.
- Brew A at 90°C with 20 g coffee and 320 g water. Note actual preparation, pour and finish times.
- Brew B at 93°C using the same masses, grind and pour. Do not change grind or dwell time to compensate for your expectation of temperature effects.
- Compare when both beverages reach a similar drinking temperature, not immediately at different serving temperatures. Repeat with the order reversed.
Record what actually happened
Kettle setting, any actual reading and location, preheating routine, delay between heating and pouring, final drawdown and taste at a comparable serving temperature.
Use the unfilled table below as a prompt. To retain your own observations, download the blank CSV sheet or save A and B as separate brew records in My brews. Text typed into a downloaded file stays in that file; it is not synchronized to the journal.
| Record after brewing | Cup A | Cup B |
|---|---|---|
| Actual dose, water or yield | Your observation | Your observation |
| Actual grinder / setting | Your observation | Your observation |
| Actual time and timing convention | Your observation | Your observation |
| Taste and confidence | Your observation | Your observation |
| Enjoyment and next step | Your observation | Your observation |
This download contains labels and blank observation cells, not fabricated sample outcomes.
Interpret without overclaiming
A perceived difference may justify a personal follow-up, but the cause could include cooling, preparation or sensory temperature. An apparent lack of difference is a useful observation. Keep kettle setpoint and beverage tasting temperature as separate records.
What this cannot establish
A three-degree step is an editorial comparison size, not a standard or guaranteed noticeable difference. Instrument accuracy, altitude and heat loss may exceed the step. No microbiological or equipment-safety conclusion follows.
Choose the next test
If repeated pairs suggest a preference, retain that setpoint and repeat the original recipe before changing any other parameter.
In the journal, select the actual A and B records and check dates before drawing a conclusion. The paired comparison link uses the latest saved record for each experiment recipe; it is not a statistical test and may select different sessions. A repeated pair with reversed preparation order is more informative than a single cup, but it still describes your coffee and conditions.
References and scope
NIST: controlling nuisance factors in experimental design. This reference supplies background, not a validation of BrewLab’s recipe values or proof of any result. The protocol, example settings and record sheet are independently written for this site.
Use stable equipment and handle hot water carefully. Follow brewer and basket capacity instructions. No recipe, taste or date in this guide establishes food safety or equipment suitability.
All six experiment plans →