Hardener selection chart places FH743 at 90 F and above. FC740 Super Brillante Clearcoat uses a 4:1 clearcoat-to-hardener mix ratio with FH741, FH742, or FH743 hardener. FC750 Satin Clearcoat uses FH743 in its 4:1 mix with FH741 or FH742 alternatives.
