Abstract: Precipitation of polyacetylenic agents can be effected with control of a particle size parameter such as mean size or spread, by mixing a warm solution of the acetylenic agent with a cold precipitation fluid and appropriate selection of a constituent of the cold precipitation fluid and/or of the temperature conditions and collecting the precipitated acetylenic agent. Precipitation additives such as nitrocellulose or gelatin can usefully be employed. Solvents such as aqueous methanol and ethyl 3-ethoxypropionate can be useful. Polyacetylenic agents, e.g. substituted diacetylenics are useful to provide visual changes in condition-monitoring indicators such as time-temperature indicators, “TTIs”, useful as freshness indicators for radiation exposure monitoring and for other purposes. Controlled, small and/or consistent particle sizes of such polyacetylenic agents are helpful in providing consistent commercial properties, especially in inks in which they may be formulated.

Abstract: A system for recovering a diacetylenic monomer shelf life monitoring compound of reduced particle size and narrow size distribution range which comprises quenching a solution of the monomer by mixing the solution in a lower temperature quenching fluid having a base temperature which is at least about 30° C. below the nominal temperature at which the monomer compound recrystallizes from solution, the mixing being effected in such a manner as to limit the resulting quenching mixture temperature to one which is not higher than a maximum of about 15° C. above the quenching fluid base temperature.