What is an Acceptable Damp Reading?

Damp readings are an important consideration when it comes to assessing the condition of a collection. An acceptable reading can help ensure that the items in the collection are not being damaged by moisture.

The ideal relative humidity (RH) for museum collections is generally considered to be between 45% and 55%, with a fluctuation of no more than 5% per day.

Interpreting Damp Readings

When interpreting damp readings, it is important to consider the following factors:

• The type of material being measured: Different materials absorb and release moisture at different rates.
• The temperature of the environment: As temperature increases, the air can hold more moisture.
• The length of time the material has been exposed to moisture: Prolonged exposure to moisture can cause damage.

Acceptable Damp Readings

The acceptable damp reading for a particular collection will vary depending on the factors listed above. However, the following general guidelines can be used:

• Paper and textiles: 50% to 60% RH
• Wood and furniture: 40% to 50% RH
• Metals: 30% to 40% RH

Monitoring Damp Readings

It is important to monitor damp readings regularly to ensure that the environment is within the acceptable range. This can be done using a hygrometer, which is a device that measures the relative humidity.

If the damp readings are outside of the acceptable range, steps should be taken to adjust the environment. This may involve using a humidifier or dehumidifier or changing the ventilation.

Conclusion

Damp readings are an important part of assessing the condition of a collection. By understanding what an acceptable reading is and how to interpret damp readings, you can help protect your collection from damage.