From your question, it is assumed that you have got blotchy skin while sun tanning yourself. If it is so, you probably have had too much exposure to ultraviolet (UV) rays and have got yourself sunburnt. Exposure to ultraviolet rays in the sun makes the skin to produce the pigment melanin, which gives the skin a dark tan. Limited sunbath can give you an even tan, and is considered normal. However, unprotected and overexposure to sun's rays may result in blotchy suntan.
To avoid a blotchy look after a suntan, one should take certain precaution while tanning in the sun. First of all, one should carefully choose a sunscreen lotion with correct sun protection factor (SPF), which is generally denoted by a number. Basically, a higher SPF number means that it will give more protection from ultraviolet rays. Here, it is also to be kept in mind that there are two components of UV rays, UVA and UVB, and the skin needs protection from both. In fact, one should be more careful about protecting the skin from UVB as it is considered more damaging to the skin. Therefore, the sunscreen you choose should have full UV protection against both the types.
It is also recommended that sunbathing in direct sunlight should be avoided between 10 am and 4 pm, as the sun's rays are strongest at this time. Even if you do need to go out sunbathing during that time, ensure that you have applied sunscreen lotion properly and you take frequent breaks to come into the shade. Sunscreen lotion is best applied half an hour before going out in the sun and then once again after about half an hour into sunbathing. It should be re-applied on the skin if the lotion sweated or rubbed off. If you take a swim, it should be re-applied too. Care should also be taken to apply sunscreen lotion in a thick and even layer. Uneven application of sunscreen lotion can expose some body parts to more UV radiation than the others, which eventually will cause uneven tanning and give a blotchy look. Often, people misjudge the amount of sunscreen lotion to be applied, and end up getting sunburnt. It is, therefore, always better to get sunscreen lotion with higher SPF number just to be on the safe side. Also, take special care to protect your eyes from UV rays - wear a hat and a UV-protected sunglass, always, when you are exposing yourself to direct sunlight. In case one doesn't want to sit in the sun, there are also some self tanners available in the market that claims to give a tanned look without really getting into direct sunlight.
answered by G R