Fabrics
18. It is advisable to ascertain the composition of a fabric or cloth before buying it to use for sewing. This avoids the potential aggravation of finding out after sewing something that the fabric itself was shaatnez. However, since fabrics that are shaatnez themselves are generally uncommon, checking them is not obligatory (השעטנז למעשה ), besides for the following fabrics:
19. Fabrics which must be checked. A fabric or garment that has threads of varying thicknesses or different colors must be checked for shaatnez even if the label says it is made of 100% synthetic materials (תורת השעטנז ).
Suits
20. Suits, jackets. Men's, women's, and children's suits and jackets have different areas that need to be reinforced. Since linen is a strong material, they are reinforced with pieces of linen fabric or with linen thread to increase their durability. These areas must be checked on all suits. Some examples: the suit's lining, collar filling, collar reinforcement, shoulder pads, reinforcement strips or linen threads at the sleeves' stitching, and buttonholes, as well as the thread used to sew the buttons. There are other areas in addition to these that shaatnez checkers are familiar with.
21. Suits made of at least 50% wool. Any suit which has wool as the majority of its composition is halachically required to be checked since suits commonly contain linen threads or fabric.
22. No more than 40% wool. A fabric which is made up of a majority of a permissible material and a minority of wool is viewed as if it is entirely made up of the permissible material and may be sewn with linen (Issue 115, Paragraph 19). Nevertheless, even if a suit's primary material is less than half wool, it must be checked since it is common to find areas in these suits with added fabric, threads, or fillings, both linen and wool.
23. 100% synthetic. Suits made from a material other than wool or linen are not ossur, even if they contain some linen, unless they also have wool. Since wool is not usually added on to suits, strictly speaking, these suits do not need to be checked.
24. Hugo Boss. Hugo Boss suits are assumed to have shaatnez and may not be worn before getting checked. Sometimes they have so much shaatnez that it is not worthwhile costwise to replace all the shaatnez areas with kosher material.
25. Linen suits can contain wool cloth or thread and must be checked.
Trousers / Pants
26. At least 50% wool. Occasionally, pants contain some linen, e.g., as the filling in the waistband, over the hook and bar closure, or in the reinforcement by the zipper. However, since this occurs infrequently, these pants strictly speaking do not need to be checked. Still, it is proper to check them.
27. No more than 40% wool. Trousers whose main material is made up of only a minority of wool and pants that are 100% cotton, viscose, polyester, and the like, do not need to be checked. Even if there is linen in the aforementioned areas, it is extremely rare for there to be added wool.
Fur Hats
28. Russian fur hats frequently have cloth inside which contains wool and linen. Also, wool or fur “kutchmas” frequently have shaatnez and must be checked, even when purchased from a store owned by a frum Jew.
Coats
29. Winter coats. Winter coats with wool, whether men's or women's, whether short or long, must be checked. [As an aside, many coats contain cashmere. Cashmere is not sheep wool, which is part of the issur of shaatnez; it is made from goat hair and not subject to the issur of shaatnez. However, since it is not in great supply and very expensive, it is generally combined with sheep wool. Therefore, one must watch out for shaatnez when combined with wool.]
30. Raincoats with wool as their outer material must be checked. If neither the material nor the lining is wool, they do not need to be checked.
Sweaters/Vests
31. Wool sweaters. Sweaters made of wool or wool blend do not need to be checked if they are made from a single cloth without any added material, appliqué, and the like, since they rarely have shaatnez. Most men’s sweaters fit this description and do not need to be checked. Sweaters that have add-ons, raised embroidery, appliqué, or other fabrics, as women's sweaters commonly do, they should be checked.
32. Not made of wool or linen. Sweaters made of cotton, polyester, viscose, and the like, do not need to be checked.
Scarves
33. 100% wool scarves usually do not have shaatnez, so they do not need to be checked. If they also contain "various fibers," they must be checked.
Shoes
34. Strictly speaking, some shoes are not subject to the issur of shaatnez, which is only ossur when it feels good on the skin of the wearer's body; the skin of the feet is tough and does not "enjoy" the material covering it (שו"ע סי' ש"א סי"ג ) [see the sefer, "Toras Hashaatnez," p. 408, which goes through all the opinions, describing the types of shoes that are muttar and ossur]. However, nowadays that we always wear shoes, the skin on our feet is only very tough by the heel. Consequently, some poskim hold shaatnez is ossur in all shoes (נמוקי או"ח סי"ב סק"ג, שו"ת מהר"ם שיק או"ח סי' ק"נ ד"ה ומה שביקש ).
Sheepskin with Wool
35. There are certain clothing items today, such as sheepskin hats or UGG boots, that are made of sheepskin with its wool still attached. The poskim discuss whether there is an issur to sew linen threads in them. Some say wool still attached to the skin has the status of wool and may not be sewn with linen thread (שו"ת הרשב"ש סי' ת"ר, ט"ז יו"ד סי' רצ"ט סוף סק"א, בית הלל סי' רח"צ ).
36. Most poskim hold wool still attached to its skin does not have the halachic status of wool and may be sewn with linen thread (ע"פ ערוה"ש סי' רצ"ט ס"ה, שו"ת בית שערים יו"ד סוף סי' שפ"א ד"ה ועוד נ"ל, שו"ת יד הלוי יו"ד סי' קפ"ז, שו"ת עמק התשובה ח"ג סי' פ"ד ).
37. Since it is a machlokes, if one knows with certainty that a sheepskin has linen thread, he should be machmir as a safeguard to protect himself from any possibility of shaatnez (שו"ת עמק התשובה שם ). If one is not sure, he does not need to get it checked since even the machmirim hold it's only ossur miderabonon, and most are meikel.
38. UGGs. There are many shoes and slippers produced in Australia that are made from sheepskin with its wool. Based on the above, they do not need to be checked for shaatnez since even if they were sewn with linen thread, they are technically not ossur. However, there is a certain type with wool fabric and linen threads sewn to it, which is an issur of shaatnez. Nevertheless, one does not need to be concerned for this for every type of sheepskin footwear unless he sees or has reason to think it contains wool fabric.
39. Baby stroller sleeping bag. We were asked if a baby stroller sheepskin sleeping bag must be checked for shaatnez. A sleeping bag sewn with wool and linen used to warm the body is technically ossur due to shaatnez. Still, since sheep's wool still attached to its skin does not truly have the halachic status of wool (above, 36), one does not need to check if the sleeping bag has additional wool fabric, which would make it ossur if it was sewn with linen thread.
