  Mid-infrared photometry of R Coronae Borealis stars obtained from various
satellites from IRAS to WISE has been utilized in studying the variations of
the circumstellar dust's contributions to the spectral energy distribution of
these stars. The variation of the fractional coverage (R) of dust clouds and
their blackbody temperatures (T$_d$) have been used in trying to understand the
dust cloud evolution over the three decades spanned by the satellite
observations. In particular, it is shown that a prediction R $ \propto T_d^4$
developed in this paper is satisfied, especially by those stars for which a
single collection of cloud dominates the IR fluxes. Correlations of R with
photospheric abundance and luminosity of the stars are explored.
