Fig. 6. FTIR spectra of the adsorption of hydrated clay and filtrate loss reducers: (a) 4 wt% hydrated clay; (b) 4 wt% hydrated clay treated with 2 wt% comb-shaped copolymer reducer; (c) 4 wt% hydrated clay treated with a mixture of 3 wt% SMP and 3 wt% SMC; (d) 4 wt% hydrated clay treated with 0.3 wt% PAC; (e) 4 wt% hydrated clay treated with 2 wt% NS-1 filtrate loss reducer.