I've never used mascara primer before. I was intrigued, but wasn't sure what it was supposed to do since mascara isn't something that typically 'wears off' throughout the day. It's impossible to see how much product is on the wand, and it just makes my lashes look wet. The only thing that was nice is that it separates the lashes so that they are prepped for mascara. but a plain clean spiral brush accomplishes the same thing.
First off, I have to say I received this in my voxbox and would never have bought a lengthening mascara for myself--my eyelashes are long already. I was excited to open it and discover the brush is identical to the covergirl clump crusher brush (which I love to bits). The application is smooth and does not allow clumping. However even with the primer the formula is very thin and it didn't have the staying power I would have liked.