March 2006 

Moisture Allowance—The Official’s Nemesis; Industry’s 

Nightmare! 

By Tom Coleman 

In the past NIST has published recommended moisture allowances for use at all locations 

including point-of-pack. When officials test product for which no moisture loss guidance 

has been provided, NIST can help. The amount of moisture lost from a package is a 

function of many factors, not the least of which is the product itself (e.g., moisture 

content), packaging, storage conditions (e.g., temperature, humidity, air flow), time, 

handling and others. If a packaged product is subject to moisture loss, officials must 

allow for “reasonable” variations caused by moisture either evaporating or draining from 

the product. Officials cannot set arbitrary moisture allowances based solely on their 

experience or intuition. Moisture data and must be “reasonable.” Reasonable does not 

mean that all of the weight loss caused by moisture evaporation or draining from the 

product must be allowed. As a result of product and moisture variability, the approach 

used by an official must be developed on a case-by-case basis depending on many factors 

to include, but not be limited to, the manufacturing process, packaging materials, 

distribution, environmental influence, and the anticipated shelf life of the product. 

NIST Handbook 130 provides a starting point for developing a workable procedure in 

section 2.5.6. in the Interpretation and Guideline Section regarding “Resolution for 

Requests for Recognition of Moisture Loss in Other Packaged Products.” NIST WMD 

has worked and will continue to work extensively with the NCWM, the Laws and 

Regulations Committee, and industry to develop protocol for determining moisture 

allowances that can serve as models for future studies. Most studies involving nationally 

distributed products will require products be tested during different seasons of the year 

and in different geographic locations to develop a nationally recognized moisture 

allowance. Some studies may require the development of laboratory tests used for interlaboratory comparisons to establish moisture content in products at time of pack or at the 

time of inspection. 

In some cases manufacturers can and may provide valid moisture loss data for officials to 

consider in lieu of conducting studies. In cases like this, WMD will provide assistance to 

determine if the information is complete or if further documentation is required. For 

example, a major producer of bar soap provided moisture loss evidence for consideration 

by officials to determine what, if any, moisture loss could be expected to occur. In such a 

case, the information provided proved to be accurate, thus avoiding the need for national 

data collection. 

Moisture loss or gain is a critical consideration for any net content enforcement effort and 

one that, in most cases, cannot be addressed by a field official. If moisture loss issues are 

to be deliberated, it is the regulatory official’s responsibility to consider the packer’s 

concern, utilizing available resources and due process procedures. To fulfill this 

obligation, officials may be required to utilize specialized test equipment and specific 
laboratory procedures. Additionally, the collection of adequate test data may require 

product examination over a broad geographical area and consideration of a wide range of 

environmental factors. If a national effort is required, a coordinated effort involving 

industry, trade associations, weights and measures officials and federal agencies may be 

required. NIST will provide technical support upon request.