NO! This is a big misunderstanding. The only difference between fast hardener and slow hardeners id the solvents used to make them. Fast hardeners use fast evaporating solvents, slow hardeners use slow evaporating solvents. The only 2 items that affect actual cure time is HP1001 accelerator which speeds up cure time (NOT to be used in HC-9500 or HC9040) and POTLIFE extender which retards the cure time. Honestly using HH-7605 in all conditions except very cool conditions will have very little difference in our products, then if you used HH7607. The solvents in the "A" side are already slow. NEVER use HH-7607 in HC-9500