The following conditions apply:
- Liquids. Nonhazardous liquids, creams, and pastes (particularly those in 1–gallon paint cans with only friction–top closures) are often a source of damage to other mail and postal equipment. The proper packaging of liquids is critical to ensuring the integrity of the mailpiece during handling.
All liquids are subject to the general packaging requirements in DMM 601.1–8 and the following:
- Containers having friction–top closures are not acceptable by themselves. Such containers must be packed within a strong and securely sealed outer packaging.
- Screw caps with a minimum of one and one–half turns, soldering clips, or other effective means must be used to ensure a secure closure.
- Glass and other breakable containers more than 4 fluid ounces and any containers over 32 fluid ounces must be cushioned within a sealed, waterproof container such as a can or a plastic bag, and must be packed within a strong and securely sealed outer packaging.
- Steel pails and drums with carrying handles and positive closures (e.g., locking rings or recessed spouts under screw–cap closures) may be accepted without additional packaging.
- Powders. Dry materials that could cause damage, discomfort, destruction, or soiling upon escape (leakage) must be packed in siftproof containers or other containers that are sealed in durable siftproof outer containers.