Sex, whether solo or with a partner, is all about controlling friction. Too much friction causes pain and tissue injury. Too little friction decreases sexual pleasure. Lubes are critical tools in your sexual arsenal. Debra Herbenick from Indiana University and colleagues found that most women prefer water-based lubricants. Their conclusions were based on data taken from five-week sex diaries kept by nearly 2,500 women. The women were assigned one of six water-based or silicon-based lubricants. Water-based lubricants provided fewer genital symptoms during penile-vaginal sex, penile-anal sex, and solo sex. Women also reported greater sexual pleasure and satisfaction with water-based lubes. (Journal Sexual Medicine, published online December 9, 2010)