Sunscreen and sunblock are an important step of sun protection for areas where sun protective fabric is not practical. Many people apply sunscreens and sunblocks after sun exposure. Since a sunburn can occur within minutes, sunscreens should be applied before going outdoors. And, we can not say enough about reapplying at least every 2 hours during the day. Lotions unlike fabric can be rubbed, washed or sweat off.