1.1 This specification covers requirements for first grade concentrated natural rubber latex (see Table 1) of the following categories:Category 1-Centrifuged Hevea natural latex preserved with ammonia only or by formaldehyde followed by a This specification establishes the requirements for first grade concentrated natural rubber latex of the following categories: Category 1, centrifuged Hevea natural latex preserved with ammonia only or by formaldehyde followed by ammonia; Category 2, c