Please explain the concepts of “shatnes”, the dissimilar materials used in clothing. What is not allowed??
The Torah teaches about the prohibition against wearing a mixture of wool and linen in the same piece of clothing, as it is written, “You shall not wear combined fibers, wool and linen together” (Deut. 22:11).
Shatnez is an acronym for “combed, spun and woven,” which describes the stages in processing fabric: combing the raw fiber, spinning fibers into a thread, and weaving the threads into cloth.Shatnez is forbidden when it is worn as a normal garment — i.e. to protect from the cold, rain and heat. It is therefore permitted to try on a new outfit for size, even though it may contain shatnez.
Even the smallest amount of shatnez is forbidden. For example, if you have a wool suit and the buttons are sewn with linen thread, it is forbidden to wear the suit until the linen thread is removed.Someone who discovers they are wearing shatnez is required to remove the garment immediately.
It is likewise forbidden for a Jew to manufacture or sell shatnez clothing, unless he can be certain that only non-Jews will purchase it.Clothes that list wool or linen on the label should be taken to a certified shatnez laboratory, where they will be checked under a microscope.
Even though only one of the two forbidden fibers is listed, the odds of finding shatnez is greatly increased. Manufacturers are not required by law to reveal every element in their clothing. Even if a garment says 100 percent wool, it may legally still contain linen threads. For example, linen neckties often have a wool lining. Garments are usually safe from shatnez if neither linen nor wool are mentioned on the label.
In many cases, the shatnez can be easily removed because the wool and linen are not combined in the basic fabric of the garment. Once the shatnez is removed, it becomes permitted to wear the garment. For example, shatnez is at times found in men’s suits which are made of wool or wool blends. To retain the shape of the collar area, a canvas stiffener is generally sewn into the collar, and linen is the fabric considered by the clothing industry as being the best material for this purpose. The more expensive the suit, the greater the likelihood that linen is used. If linen is found in a collar canvas, it can easily be removed and replaced with a non-linen canvas.
It is permitted to wear a linen garment over a wool garment, or vice versa, since they are not attached to each other. For example, it is permitted to wear a linen jacket and wool pants, or a linen scarf wrapped around a wool dress, or a linen tie under a wool jacket. Buttoning a wool and linen garment together — even on a permanent basis — is not considered an attachment because the garments can be easily unfastened. It is therefore permitted to wear a wool coat together with an inner lining of linen, if they are buttoned (but not sewn) together. The same applies with snaps or Velcro, since they can be easily detached.
There is one restriction, however, in wearing wool and linen garments on top of each other: One needs to determine if the inner garment can somehow be removed without completely removing the outer garment. If not, then the garments are considered attached to one another. Therefore, wearing wool pants over linen underwear is considered shatnez. So when wearing one garment of wool and one of linen — like coats, sweaters, jackets, dresses and blouses — one must determine if the garments underneath can be removed without removing the top one first.
While the Torah prohibits wearing shatnez (“shatnez on the body”), “shatnez beneath the body” (e.g. upholstery and carpets) is forbidden by rabbinical prohibition. Therefore, sitting, lying, or walking on shatnez is prohibited when there is the concern that the shatnez material may come off and cling to the body.This prohibition largely depends on the softness of materials used. For example, if the shatnez material used in the seat of a chair is soft or plush, it is forbidden to sit on the chair.Wool carpets can also be a problem, as linen is sometimes used as a backing. Walking barefoot or sitting on a shatnez carpet would be prohibited where there is direct body contact. If the carpet is tightly woven, and loose threads are unlikely to come off, the carpet would not be a problem.[from aish.com]