Frequently Asked Questions - Preservation Method 50

Listed below are portions of MIL-STD-2073 covering preservation method 50 (formerly Method II) for watervaporproof protection with desiccant. This web page identifies the method, types of materials authorized, a graphic illustration, and a link to the School of Military Packaging Technology's 'How To' web documents. If this material does not enhance your understanding regarding this method of preservation, please use either our feedback form to provide recommendations or contact us directly by E-mail us at:

  • How should items that require Method 50 be packaged?
    MIL-STD-2073 states, 'Items protected in accordance with Method 50 shall be sealed in a watervaporproof enclosure with activated dessiccant as required. Unless otherwise stated in the contract or purchase order, unit packs of all of these methods shall include a humidity indicator. Projections, sharp edges, or other physical characteristics of the item which may damage the watervaporproof bag or container shall be cushioned as required in accordance with 5.2.3. The item shall also be cushioned as required to mitigate shock, thereby preventing physical and functional damage to the item. Unless otherwise specified, preservative coating requirements shall be determined in accordance with When bags are used, the bag size shall be of sufficient surface area to premit two subsequent resealings after the item after the item inspection, unless otherwise specified. Unless prohibited in the contract or purchase order, carrying cases or housings, which function as a sealed container, may also be used as the watervaporproof enclosure within which the desiccant and humidity indicator will be placed. Precautions must be prominently noted on the item cases or housings that the desiccant and indicator cards must be removed prior to placing the item into use. Requirements for desiccant and humidity indicators are as follows:'  

    • Desiccant (activated) - 'The bagged, activated desiccant shall conform to MIL-D-3464. Type I shall be used unless Type II or III is specified or required because of special characteristics of the item. Desiccant shall be in standard unit sized bags. The desiccant shall be strategically located in the pack so as not to be load bearing. Optimally, it should be placed in voids of the item or pack interior. Desiccant shall be adequately secured to prevent its shifting or movement or placed in specially designed desiccant baskets affixed to the container interior. Under no circumstances shall desiccant be permitted to come in direct contact with critical surfaces of the enclosed item. The desiccant shall not be unnecessarily exposed to the ambient environment when removed from the selaed desiccant storage container. Removal of the desiccant and its insertion into the unitpack shall be the last action prior to effecting the final seal of the bag or container.'  

    • Quantity of Desiccant - 'The minimum quantity of desiccant to be used per unit pack shall be computed in accordanced with either Formula I or II as applicable. The various values of 'X' take into consideration the quality and types of dunnage. The inner container (when applicable) must be considered in the dunnage calculations'.  

    • Humidity indicators - 'Humidity indicators shall conform to MS20003, unless otherwise specified in the contract or purchase order. The humidity indicator shall be firmly secured directly behind the inspection window or immediately within the closure seal of the container. When specified, externally mounted humdity indicating elements or devices shall be installed in the barrier or rigid container used to effect the unit pack. Unless otherwise specified, externally mounted color change humidity indicating devices shall conform to MIL-I-26860.'  
    All packs prepared in accordance with any method of this basic group shall pass the applicable quality assurance tests specified in tables G.I and G.II.'

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Last Updated:  5 Oct 2015