Which is more likely to kill sperm70% rubbing alcohol or 91%rubbingalcoholbecause someone said 100% etho evaporates as soon as you open it so because its so strong 91% would likely do the same instead of killing the sperm?it solidfies over killing??

Equally effective but definitely not needed. This will not improve on whatever your contraceptive is. Nobody ever gets pregnant without semen ejaculation inside the vagina; there is no risk for semen from surfaces, on fingers, etc.

Both are an overkill Sperms die within 10 mts when not in vagina. Soap and water is enough. Do not use any of these products- specially in the genital area