Similar to methamphetamine, DMT, or just about any vaporized substance, the longer you hold it in, the more of the vapor you will absorb. This is different from cannabis smoking because weed is actually combusted and burned with radiant energy from a lighter's flame to produce smoke. So in weed smoke, you see, there are multiple cannabinoids, terpenes, and various other pyrollized, phyto compounds. A study in Australia found we absorb ~95% of THC from weed smoke within the first 3 seconds after taking a hit, so with cannabis, it's not worth holding your breath longer than 3 seconds for the extra ~5% due to the fact that you're exposed to harmful smoke longer than is worth the extra ~5%. This is not the same for crack cocaine, but it also depends on cuts and purity, I'm sure.
In theory, assuming you have a pure enough product, the cocaine base vapor should be entirely composed of (or mostly, at least) cocaine freebase (read: more-or-less “crack” for all intents & purposes). And if you hold your hit long enough, you'll breathe out nothing visible – further evidence of a higher bioavailability.
Perhaps prepare a glass of salt-water or epsom-salt-water and swish your mouth out with it after each hit of crack. Salt water and Epsom water (MgSO4) heal and either could possibly help remove any weird pH-causing drug residues.
Also next time you use, try not to over-do the torch lighter / heat source. Many times, the high temps are rough on the mouth, tongue, lips, etc. Also, start using chapstick or blistex or whatever… that might help. Holding your hits will furthermore help you avoid blowing out as many irritating vapors, and finally: exhale through the nose so as to avoid the mouth, as well. Good luck!