The invention relates to a printed article and a feedstock for printing comprising a matrix forming material, in particular a polymeric material, and a filler material dispersed within the matrix forming material, in which the filler material comprises glass flakes. Glass flakes are characterized as having an aspect ratio of average diameter divided by average thickness greater than or equal to three. Selecting aspect ratio of glass flakes controls an orientation of glass flakes angled relative to a printed layer and formation of a depletion layer in a printed article. Technical effects of angled flakes include better adhesion between successive printed layers in 3D printing and a crack-stopping function. In a preferred embodiment the glass flakes comprise a conductive coating such that a printed article functions as a moisture sensor. Technical effects of a depletion layer include high moisture permeability and so a fast rate of change in electrical resistance due to moisture. A process of manufacturing a feedstock and a process of printing comprising a step of providing glass flakes are also disclosed.