Aging cheese needs 50-58°F (10-14°C) and 80-90% humidity, plus gentle air movement and darkness. Humidity can be measured with two thermometers, one wrapped in a wet wick, but at 12°C the wet bulb reads only 0.9 to 1.8°C below the dry bulb across the whole 90% to 80% band, so a thermometer that cannot be read to a tenth of a degree cannot tell a good cave from a bad one.
Part of Dairy Production at Scale
The aging conditions are the temperature and relative humidity at which a pressed cheese ripens without drying out, sweating fat or growing the wrong mold.
The Band Is Narrow, And Each Edge Has A Different Failure
The parent article specifies 50-58°F (10-14°C) and 80-90% humidity. Cheese Basics gives 10-15°C and the same humidity band, so the ranges agree where they overlap.
| Condition | Too low | Too high |
|---|---|---|
| Temperature | Ripening is slow | Cheese ripens fast and may sweat fat |
| Humidity | Rind cracks and cheese loses weight | Slime and unwanted mold |
| Air movement | Mold builds up (dead air) | Cheese dries |
Hold temperature steady rather than perfect: a cave that swings widely within the band is worse than one that sits at 54°F all year.
What You Need
- Two thermometers of the same make, one wrapped in a clean wick of cloth
- Clean water for the wick and a way to move air over it, such as swinging the pair on a cord for a minute
- A pan of water and a damp cloth to raise humidity; a gentle draft to lower it
Method: Measuring Humidity With A Wet Bulb
Wrap the bulb of one thermometer in a wick wetted with clean water and fan it. Evaporation cools it to the wet-bulb temperature; the difference from the dry bulb tells you the humidity. The drier the air, the bigger the difference.
Worked Example: What 80-90% Looks Like On Two Thermometers
At a dry-bulb of 12°C (53.6°F) the difference between dry and wet bulb for each humidity is:
| Relative humidity | Wet-bulb depression at 12°C |
|---|---|
| 90% | about 0.9°C |
| 85% | about 1.3°C |
| 80% | about 1.8°C |
These were computed from the Magnus vapor-pressure formula and the standard psychrometer constant of 0.00066 per degree at sea-level pressure, both from general knowledge and not from this wiki, so treat them as approximate. The working for 85%:
- Saturation vapor pressure at 12°C is about 14.0 hPa, so the air holds 0.85 × 14.0 = 11.9 hPa.
- A wet bulb at 10.7°C has saturation pressure about 12.8 hPa, and subtracting the psychrometer term 0.00066 × 1,013 hPa × 1.3°C ≈ 0.87 hPa gives 11.9 hPa. It matches, so the depression is 1.3°C.
The practical lesson is that the whole 80-90% band spans less than 1°C of wet-bulb difference. A thermometer marked in whole degrees, or read by eye to half a degree, cannot place a cave inside the band. Use one with 0.1-0.2°C resolution, check both against each other in the same air first so any offset between them is known, and measure at several spots.
Method: Adjusting The Cave
Too dry (high depression): set a pan of water on the floor, hang damp cloths, or reduce ventilation. The parent article names the water pan.
Too damp (low depression, slime on rinds): increase ventilation, and wipe mold with a cloth dipped in salted water or vinegar as Cheese Basics advises.
Too warm: this is a site or depth problem and cannot be fixed with a pan; see Natural cave vs built cellar.
Common Mistakes
- Putting the wet-bulb thermometer in still air. It will read too high and the cave will look wetter than it is.
- Using one thermometer for both readings in turn. The wick cooling it makes the second reading wrong.
- Chasing a perfect number. Stability matters more than any one reading.
- Opening the door in summer to cool a cave. Warm outside air cools on the cheese and condenses on it.
Safety
Wet floors and closed rooms
A damp cave floor is slippery and low spaces can hold carbon dioxide; ventilate before entering a space that has been closed for days and do not enter alone.
What’s Next
- Learn next: Shelving and air circulation — moving the air
- Combine with: Natural cave vs built cellar — choosing a site that holds the temperature