The objective of this SERDP Exploratory Development (SEED) project was to investigate the technical feasibility of developing a new pyrotechnic obscurant material based on ingredients that are environmentally benign. Furthermore, the material should generate a combustion product (smoke) that is low in toxicity during functioning.

The focus in this SERDP effort was the use of a sea-salt based smoke generating obscurant with a low toxicity for flora and fauna. This research contained four main activities:

• A desk study to choose a limited number of sea-salt based components and rank them according to low toxicity, low ecotoxicology, low persistence, low bioaccumulation and hygroscopic.

• Selected various base compositions containing the chosen components.

• Performed labscale testing to obtain information about the safety (friction and impact), the smoke formation (transmission), the formed particle size and particle size distribution and toxicity (by in vitro testing).

The proof of concept. A scaled down version of a hand grenade with the most promising composition was and tested on a proofing ground.

The compositions made contained various amounts of sodium chlorate, cellulose, calcium carbonate and magnesium (from two different sources). From the laboratory scaled tests, the composition named “11EM0745” was the best performing composition. When these compositions are compared to the benchmark obscurant compositions (hexachloroethane smoke, red phosphorus (RP) smoke, and terephthalic acid based smoke) it is concluded that the transmissions through the sea-salt compositions are much higher compared to the hexachloroethane smoke and RP smoke, but lower compared to the terephthalic acid based smoke. The smoke from developed compositions are less toxic than the hexachloroethane, RP and terephthalic acid smokes. Furthermore, the ingredients used are easy to obtain and low in costs.

With these results in mind, it seems feasible to obtain a less toxic smoke forming composition based on composition 11EM0745. However, some fine tuning is needed to further reduce the transmission of the smoke.