29Si NMR spectra of dry samples: a) single pulse spectrum of calcined 7% sample, b) single pulse spectrum of calcined 13% sample, c) 1He29Si cross-polarization spectrum of calcined 13% sample, d) single pulse spectrum of calcined steamed 7% sample (4000 scans), e) 1He29Si cross-polarization of the calcined steamed 7% sample. The small lower right inset is a superimposed plot of the d) and e) spectra where the left part of the spectra are normalised to show the enhanced signal in this region.