Mats with a printed design make it easy to know which side goes up and which side goes down. If you've purchased a sticky mat that has a design on one side, the side with the printed design will be the side that you work on top of. If there isn't a design and the texture feels the same on each side, you can use either side of the mat. Mats like these will often be labeled or marketed as reversible yoga mats. If the texture feels smoother on one side compared to the other, then put the smoother side down on the floor -- your feet will have more traction on the side that has more texture.
Sticky mats are made from different materials, including synthetic chemicals. Sticky mats with a printed design are often made with polyvinyl chloride, or PVC for short, or other chemical materials that give off an unpleasant or toxic odor. This can be distracting when you’re in poses like Downward-facing Plank or Cobra. To speed up the off-gassing of these chemicals, wash your mat in a mild detergent with warm water and let it air dry outside.
Textured mats that are environmentally friendly are made from natural resources such as all-natural rubber, hemp and jute or recycled rubber. How sticky a natural or environmentally friendly mat feels to you will depend upon its texture. For example, an all-natural rubber mat will closely resemble the feel of a sticky PVC mat, whereas a hemp or jute mat may not feel as sticky. However, they still provide traction. You can usually use either side of these mats during your yoga session.
If you’re taking a yoga class, most instructors will suggest you work barefoot on a sticky mat to get the best traction. If you choose to use no-slip yoga socks, the side of the sticky mat you use won’t be as important. No-slip yoga socks give you a firm grip on all kinds of mats. Going barefoot or wearing no-slip yoga socks is a personal preference -- how cold or hot your feet feel will influence your decision.