When placing your tubes in the microcentrifuge, If your research supervisor doesn’t have a preference, then always place the tubes hinge up. If you develop this habit, it might serve you well--depending on the type of research you do.

For example, if you have a pellet after the spin, you’ll always know that it will be opposite the hinge*. If instead of a pellet, you have a streak of material on the side of the tube, you'll know which side to avoid when pipetting off excess liquid.

In our work, we often pour liquid out of micocentrifuge tubes into a waste container. Pouring that liquid over a hinge would be unnecessarily messy.

In addition, when you work with certain columns, it’s critical to place them in the microcentrifuge in the same orientation for each spin. Developing the habit of placing your tubes hinge up will help ensure that you automatically place the columns in correctly with each spin without having to think much about it.

*Of course this does not apply if you're using a swinging bucket rotor in which case the pellet will be at the bottom of the tube.