I have little sympathy for folks veins who have used crack in their snowballs. If your going to do it, think again and try not to bother. If your determined then the only sensible choice is to use good quality hydrochloride cocaine powder.
Crack has been treated to make a product that has excellent BA and instant effect when smoked. When you break it down for IV, your just undoing the effort that has gone into this process. It wont hit as quick as when smoked, and requires alot more citric / ascorbic to produce an injectable solution than brown heroin alone, which is double stress on ones wirework. I really cant see why folk cant just cook up a hit, and smoke their rock immediately prior to (or immediately after) cranking the shot of gear. You will get the same effect, which is slightly more tweakable due to the choice you have over which drug you take first, and your veins will thank you for the acid you didn't have to use when cooking up.
Crack is perfectly designed for smoking, it requires no farting around and the hit is quicker than IV. Why anyone would want to ruin it and turn it back into coke for a cheapo snowball just doesnt scan, but I know Im getting all mother hen so I still stand by each to their own and all that.