  We present an investigation on escape fractions of UV photons from a unique
sample of lensed low-mass emission line selected galaxies at z < 3.5 found in
the SHARDS Hubble Frontier Fields medium-band survey. We have used this deep
imaging survey to locate 42 relatively low-mass galaxies, down to
$log(M_{*}/M_{\odot}) = 7$, between redshifts 2.4 < z < 3.5 which are candidate
line emitters. Using deep multi-band Hubble UVIS imaging we investigate the
flux of escaping ionizing photons from these systems, obtaining 1$\sigma$ upper
limits of $f^{rel}_{esc}$ ~7% for individual galaxies, and < 2% for stacked
data. We measure potential escaping Lyman-continuum flux for two low-mass line
emitters with values at $f^{\rm rel}_{\rm esc} = 0.032^{+0.081}_{-0.009}$ and
$f^{\rm rel}_{\rm esc} = 0.021^{+0.101}_{-0.006}$, both detected at the
~3.2$\sigma$ level. A detailed analysis of possible contamination reveals a <
0.1% probability that these detections result from line-of-sight contamination.
The relatively low Lyman-continuum escape fraction limit, and the low fraction
of systems detected, is an indication that low-mass line emitting galaxies may
not be as important a source of reionization as hoped if these are analogs of
reionization sources. We also investigate the structures of our galaxy sample,
finding no evidence for a correlation of escape fraction with asymmetric
structure.
