Source: Otthon.hu
When cleaning a rug, it is important to consider what material it is made from, as this greatly affects both the cleaning method and how the rug should be handled.
Synthetic rugs: New rugs made from polypropylene or polyester need only a short time for their fibres to settle and become more compact. With synthetic fibres, this usually takes two to three weeks.

During the first few weeks, some fibre shedding may occur. This is not a defect in the rug. Small loose fibres left behind during cutting and surface trimming may simply come away. It is best to avoid vacuuming during this period. After that, synthetic rugs can be vacuumed and cleaned with a neutral rug-cleaning foam or stain-removal spray.
Natural wool rugs: Rugs made from natural wool should only be vacuumed after about three months. Wool yarn consists of many individual fibres, and not all of them become firmly secured in the knots immediately. They need time to settle among the bound fibres. Regular walking on the rug can help this process. With wool rugs, shedding and breakage of loose fibres may continue for up to six months.

Begin vacuuming only on the lowest power setting. Dry foam is recommended for cleaning. If you use water, avoid soaking the rug and clean it in dry weather, as wool can absorb a large amount of moisture. Use a neutral cleaning product and lukewarm water.