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The white layer that you describe is probably smegma
- collection of shed skin, genital gland secretions and moisture. It is a harmless collection seen especially in uncircumcised men. Rarely it can get infected causing pain, rashes, foul smell, discharge and so on.
It does not need any treatment. So do not worry. Good personal hygiene and regular cleaning will keep you from harmful effects.
may reduce this problem if its bothering you much.
Hope this answers your query.
Wish you good health.