Certain things go together naturally, like peas and carrots. And certain things don't, like toothpaste and orange juice.
The Torah teaches about the power of combinations and warns against mixing the wrong things together. One of these is 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).
In Hebrew, this forbidden mixture is called "shatnez" (pronounced shot-nezz).
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.
We send suspicious items to a shatnez laboratory for checking.
The mitzvah of shatnez still applies today. We observe the mitzvah by checking manufacturer labels on the clothes we buy, and by sending suspicious items (like wool suits and coats) to a "shatnez laboratory" for checking.
Clothes are a unique part of being human; only people wear clothes. Shatnez is a constant reminder that all our actions must be "kosher."
Interestingly, "holy garments" are exempt from the prohibition of shatnez. For example, the special garments worn by a Kohen while serving in the Holy Temple contained both wool and linen. Similarly, it is theoretically permitted to wear tzitzit that has shatnez (though there are technical factors which don't allow this today). The explanation may be that these garments are already inherently "kosher."
WHAT'S THE REASON?
The Torah does not explain the reason for shatnez, and it is categorized as a chok -- a law whose logic is not evident. The Torah has many such laws; we do not know why pork is forbidden, for example. And the prohibition of shatnez is equally strong.
Why did God make a chok in the first place? What's the purpose of a commandment whose reason we have no inkling of?
The power of a chock is as follows: If the reasons for all the mitzvot were as obvious as "don't murder" or "don't steal," then a person could go through life without developing a relationship with God. How so? Just as there are many fine, upstanding people who don't murder -- not because they believe in God, but simply because they understand that it's wrong -- we might likewise observe mitzvot simply because they "make sense."
Leaving God out of the picture would be missing the point entirely.
Leaving God out of the picture would be missing the point entirely. That would be humanism, not Judaism.
Having said all this, God still wants us to use our intellect to understand the mitzvot to the best of our ability. Thus the commentators suggest different "explanations" for shatnez.
One idea is that he mixing wool and linen upsets the environmental and/or metaphysical fabric of the universe. God created different species that work together in the symphony of creation. Our job is to respect and appreciate this diversity and help maintain this special orderliness.
The Midrash suggests that the reason stems from the story of Cain and Abel, as recorded in Genesis chapter 4. Cain brought God an offering of flax (the source of linen) and Abel brought a sheep (wool). The incident resulted in Cain killing Abel, and it was thus decreed that never again shall the two substances mix.
This is perhaps hinted to by the Torah juxtaposing the prohibition of shatnez with the imperative to "love your neighbor as yourself" (Leviticus 19:18-19). Each person must cherish his own uniqueness and not feel threatened by others. Cain did not understand that he and his brother had different tasks in life, different roles in creation.
PRACTICAL LAWS OF SHATNEZ
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.
The smallest amount of shatnez is forbidden, even a wool suit whose buttons are sewn with linen thread.
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.
GETTING CLOTHES CHECKED
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. Checking a suit usually costs around $10.
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. Though men's suits and winter coats should be checked for shatnez regardless of the listed materials.
Also be aware of clothes containing reprocessed materials or unknown fibers, frequently listed on garment tags as O.F. (other fibers).
Once the shatnez is removed, it becomes permitted to wear the garment.
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 commonly 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.
Years ago I had the opportunity to be in Russia. American money was so valuable there that I was able to ride a public bus for one-tenth of one cent. Everything was so cheap, so one day I went to the biggest department store in Moscow, determined to buy the most expensive item I could find. After searching through aisles of mostly-empty shelves, I came to the men's clothing department where I bought a brand new suit for the equivalent of 5 dollars!
When I returned home, I went to the local shatnez-testing lab. There they had a chart on the wall, showing the percentage of suits found to contain shatnez, based on their country of manufacture. Suits from Russia have shatnez 95 percent of the time! I decided to have the lab check it anyway, and they reported back that the suit was so rife with shatnez mixture that it could not even be fixed. This story is more the exception than the rule, but I learned a good $5 lesson!
To locate a shatnez lab in your city, visit http://shatnez.n3.net/, or call the National Committee of Shatnez Testers at 800-SHATNES (800-742-8637).
Those interested in training to become a shatnez tester can contact the National Committee of Shatnes Testers and Researchers at 732-905-2628.
ONE GARMENT WORN OVER ANOTHER
There are a few more details about shatnez that are important to know.
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.
One final issue:
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.
Sitting or walking on shatnez is prohibited when the materials may come off and cling to the body.
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.
If there is doubt about the fabric content of upholstery and carpets, you should arrange to have them checked by a shatnez laboratory.
There is a story about the "Steipler," a great 20th century rabbi. He arranged for a date with a young woman in a distant town, which necessitated taking a train to get there. The night before the train ride, he stayed up all night learning Torah, thinking that he could make up his lost sleep on the train. But upon entering the train, he suspected that the seat cushions contained shatnez -- and wound up standing throughout the entire journey, continuing to study.
When the Steipler arrived and met the young woman (actually the sister of the Chazon Ish) for their "first date," he proceeded to fall asleep right away. The woman was riled, but upon checking into the matter she discovered what had happened -- and was so impressed that she insisted they be married!
For further reading, see the book, "A Guide to Shatnez," by Rabbi Dovid Loebenstein (available at eichlers.com).
with thanks to Gavin Enoch