摘要 |
<p>Uniform cheap and highly reproducible colouration of sand limestone brick by addn of mineral pigments. G6A. Diluted pigment batch with particle size above 0.1 min. (1 to 25 wt.% on dry brick batch) is added to the main batch, to reduce sensitivity of brick colour to pigment wt. variation. Pref. pigment is slate-fires, which is cheap, easily milled and imparts a dense black colour. (Others are felspar, glass foil and slag). More vivid surface effect is produced using a i size fractions of pigments i.e. (1) fine and (2) coarse (above 1 mm yields a flasked highlighted surface).</p> |