How to choose fabric for sewing: fiber, grain, labels and preshrinking

Fibers, wovens and knits, grain and bias, what the bolt end tells you, preshrinking the way the finished item will be washed, and squaring fabric on grain.

1. Fibers: what heat and water do to them Understand

Fabric is made of fibers, spun into yarns, then woven or knitted. The fiber decides most of what happens at the ironing board and in the washer. The University of Georgia Extension's fiber guide sorts fibers by what heat does to them (UGA Extension, Understand Your Fibers). Cotton, linen and rayon do not melt, but they can scorch. Acetate, nylon, polyester, olefin, spandex and modacrylic melt. Physical principle A melted patch looks glazed or becomes a hole; a scorch turns yellow or brown. Neither comes out.

Water matters as much as heat. UGA's guide says rayon is weaker when wet and may shrink or stretch unless it has been treated, and that wool may shrink and felt in the wash unless it is blended or treated. Physical principle Felting is the matting of wool fibers into a denser, smaller cloth with heat, water and agitation; it is the reason a wool sweater can come out of a hot wash a size smaller and stiff.

The pressing column comes from New Mexico State's pressing guide and UGA's fiber guide (NMSU Guide C-309, Pressing Pointers); the two NBS notes come from the National Bureau of Standards' 1970 consumer guide to fibers, which is old enough that we use it only beside current sources (NBS, Fibers and Fabrics, 1970). Cutting, marking and pressing uses this table to set the iron. Every UGA fiber entry begins by telling you to follow the care label, and that is the right order: the care words on the bolt end come first, and the fiber table explains them. Convention

A blend is a fabric of two or more fibers, such as 60 percent cotton and 40 percent polyester. For heat, a blend behaves like its most heat-sensitive fiber: a poly-cotton blend is pressed at the polyester setting, not the cotton one (Cutting, marking and pressing).

2. Woven, knit and grain

A woven fabric is made of two sets of yarns crossing at right angles on a loom. A knit is made of one yarn, or one set of yarns, looped through itself, which is why a T-shirt stretches and a shirt does not. The University of Kentucky Extension's grain sheet gives the terms every pattern uses (UK Extension, Understanding Fabric Grain):

• Grain is the direction the yarns run.
• The lengthwise grain (the warp) runs parallel to the selvage. These yarns are usually stronger and more stable, which is why most pattern pieces are cut with their length along it.
• The crosswise grain (the weft or filling) runs from selvage to selvage, at right angles to the lengthwise grain. It has a little more give.
• The selvage is the firm, finished edge along each side of the fabric as it comes off the loom. It does not ravel.
• Bias is any diagonal direction. True bias is the 45-degree line halfway between the two grains, and it stretches the most.

Pull a scrap of quilting cotton three ways and you can feel all three: almost no give lengthwise, a little crosswise, and a lot on the diagonal. Physical principle That difference is why grain matters. A piece cut off-grain, with its length at an angle to the yarns, sits partly on the bias. Seamwork's article on grainlines describes the result: off-grain pieces stretch more, twist around the body and can grow as they are worn (Seamwork, Do You Really Have to Cut Fabric on the Grainline?). UK's sheet lists stretching, sagging hems and discomfort.

The UK sheet also explains how fabric goes off-grain in the first place. It leaves the loom with its yarns square, then goes off-grain during dyeing, printing, finishing and winding onto the bolt. Section 4 shows how to check and correct it.

Knits and their stretch

A knit has wales, the lengthwise ribs of loops, and courses, the crosswise rows. The greatest stretch is usually crosswise, but UK's grain sheet says to test it. UK's knit sheet measures stretch on a 4 in length of folded fabric against a ruler or the stretch gauge printed on a pattern envelope (UK Extension, Sewing with Knit Fabric):

The categories are a convention for matching a fabric to a pattern that asks for one. Convention The fabric should also spring back when you let go. The UK sheet adds that washable knits tend to shrink more than wovens, so buy extra and wash it as the garment will be washed.

3. A first fabric and its bolt end

Colorado State's 4-H clothing project sets the first unit's fabric as firmly woven, medium-weight cotton or a blend of at least 50 percent cotton (Colorado 4-H, Clothing Construction Project). The reasons are the ones in sections 1 and 2: a firm weave holds its shape under the presser foot and does not stretch as you guide it, a medium weight feeds evenly, and cotton tolerates a hot iron, so a mistake at the ironing board is unlikely to ruin it. Utah State's pillowcase project asks for the same thing: firmly woven cotton or a cotton-polyester blend, at least 42 in wide (USU Extension, Designer Pillowcase). Quilting cotton and broadcloth fit both. Convention

This manual starts with woven cotton because every Start here in Cutting, marking and pressing and Seams and a first piece is written for it. Preference

Leave for later: slippery fabrics, which shift while you cut; sheers, which show every seam allowance; napped and pile fabrics such as velvet and corduroy, whose pieces must all face one way; and plaids and stripes, which must match at seams.

Reading the bolt end

Fabric in a store is wound on a cardboard board or a roll, the bolt, and the label on its end is the bolt end. Two federal rules decide what that label says.

Fiber content. Fiber content is the list of fibers in a fabric with their percentages by weight. The Textile Fiber Products Identification Act and the FTC's rules under it require fibers to be named by their generic names (cotton, polyester, rayon, not a brand name) with their percentages by weight, in order from most to least (FTC, Threading Your Way Through the Labeling Requirements). Fibers under 5 percent may be listed as "other fiber." The FTC guide gives a 3 percent tolerance on stated percentages, and none when the label names a single fiber, so "100% cotton" means what it says. The rule's own example: a fiber labeled 40 percent may be anywhere from 37 to 43 percent (16 CFR Part 303, §303.43). A "60/40" blend is approximate. Rayon may appear as viscose, its ISO name. Fabric cut from a properly labeled bolt needs no label of its own, so the bolt end is the only record you get: write it down before you leave the counter. Convention

Care. The FTC's Care Labeling Rule requires makers and importers of fabric sold from bolts for home sewing to put care information "clearly and conspicuously on the end of each bolt or roll" (16 CFR Part 423, §423.7). The FTC's guide for businesses says it may be on the selvage, the board end, or a tag on either, and that it covers the fabric only, not trim, lining or buttons you add (FTC, Clothes Captioning). The rule puts its duties on manufacturers and importers. It puts none on a person sewing for themselves, so the bolt end is your source of care information and the rest is your decision.

Width. The bolt end gives the width. Section 4 explains why you measure it again after washing.

Care words and care symbols

A care label is the permanent label in a garment, or the care information on a bolt end, that says how to wash, dry, iron and clean the item. The Care Labeling Rule's glossary gives exact meanings to the words on a bolt end or a garment label (16 CFR 423, Appendix A). Convention

Two things follow. First, a label that says only "machine wash" is telling you the fabric can take hot water, not that it must. Second, the rule gives the iron no degrees, only settings; Cutting, marking and pressing takes up what the settings mean in practice.

Symbols. The rule lets a label use symbols in place of words, but only the symbols in ASTM D5489-96c, a 1996 edition (§423.8(g)). The FTC proposed in 2012 to allow newer ASTM symbols and the international ISO symbols, then ended that whole review in December 2023, leaving the rule as it was (Federal Register, Care Labeling Rule, 2023). Meanwhile ASTM's current guide is D5489-25 (ASTM D5489-25), and ISO 3758 reached its fourth edition in 2023, according to GINETEX, the association that licenses the international symbols. The FTC's business guide calls the ISO symbols "similar, but not identical" to ASTM's. So a bolt end or an imported garment may carry symbols from an edition the US rule does not name. When words and symbols both appear, read the words. Convention

Width and weight

Oregon State's 4-H pattern sheet says most fabric comes 44/45 in or 58/60 in wide (OSU Extension, Pattern Skills, archival copy). Quilting cotton is usually in the first group, many apparel and home-decor fabrics in the second. Convention Width decides how many pieces fit side by side, so it decides how much length you buy; the yardage converter scales a pattern's figure from one width to another.

Fabric weight is given in ounces per square yard (oz/yd²) in the US and grams per square meter (g/m², often written GSM) elsewhere. NIST's conversion factor is exact enough for any sewing purpose: 1 oz/yd² = 33.906 g/m² (NIST Guide to the SI, Appendix B.9). Physical principle Words like lightweight, medium and heavy have no standard cutoffs in any source we found; stores and pattern companies draw the lines differently. Convention Use the number when the bolt gives one, and feel the cloth when it does not.

4. Preparing fabric: preshrinking, grain and interfacing

Preshrinking is washing and drying fabric before it is cut, so that it shrinks, and loses any surface finish, before it becomes a sewn piece. The working rule, in UNH Extension's beginners' guide and NMSU's sewing-shortcuts guide, is to preshrink by the method the finished item will be washed (UNH Extension, Sewing for Beginners; NMSU Guide C-104, Sewing Shortcuts). A pillowcase that will be washed warm and tumbled low is preshrunk warm and tumbled low. NMSU suggests putting it in with a regular load of laundry, which saves a separate wash. Convention

This manual's form of the rule is: treat the fabric the way the finished item will be treated. Convention A fabric labeled dry-clean is preshrunk by a cleaner, or by the method the finished item will actually get, not by your washer, as UK Extension's fabric-preparation sheet allows (UK Extension, Fabric Preparation for Sewing). Interfacing follows its own instruction sheet (see interfacing, below). UK's sheet gives a second reason that has nothing to do with size: leftover surface finish can cause skipped stitches and build up in the machine. Wash a fabric even if you expect little shrinkage.

How much it shrinks: the shrink test

How much a fabric shrinks depends on the fabric, so the way to know is to measure your own. Test it

Colorado 4-H's textile experiments include a home shrink test: squares cut on grain, measured, soaked and agitated in hot water, dried, and measured again (Colorado 4-H, Textile Experiments).

This manual's version: cut a 6 in square on grain from one end before washing, mark its lengthwise edge, measure it both ways, wash and dry it with the fabric at the finished item's settings, press it lightly and measure again. (Colorado uses squares of at least 8 in, which read more precisely; 6 in is this manual's choice to save fabric.) The shrinkage each way is (before − after) ÷ before × 100.

A 6 in square that measures 5 7/8 in afterward has lost 1/8 in: 0.125 ÷ 6 = 2.1 percent. One that measures 5 3/4 in has lost 4.2 percent. Write both directions on the fabric sheet's shrink-test column, for example "6 × 6 to 5 7/8 × 5 13/16". The cut-size and pillow calculators take a lengthwise shrinkage percentage and add it to their fabric estimates (cut-size calculator).

Then measure the width. The square tells you how the body of the cloth moved. The full width, selvage to selvage, can differ: Utah State's skirt project notes that selvages tend to shrink more than the rest of the fabric and recommends cutting them off (USU Extension, Youth Elastic Waist Skirt). Measure across the washed fabric and use that number, not the bolt end's, for every layout. USU's same project suggests buying an extra 1/4 yd to allow for shrinkage and straightening. Convention

Squaring fabric on grain

Check the grain after washing and before you cut. UK's preparation sheet also squares the cut ends before preshrinking; USU's pillowcase project washes first and then straightens the edges. Preference

1. Find a crosswise yarn. On a woven, clip into the selvage, catch one crosswise thread and pull it gently while you push the fabric along it; the pulled thread leaves a line to cut on. USU's pillowcase project uses this method. Many firm cottons can also be torn across: snip the selvage and tear, then steam-press the stretched edge flat.
2. Fold it selvage to selvage with the squared ends matching. On a table, line the selvages up with the table's long edge; UNH's guide says that if the cut end does not line up with the table's end, the fabric is off-grain.
3. Check the fold. Seamwork's on-grain article holds the folded fabric up and shifts the layers until the fold hangs without diagonal drag lines (Seamwork, How to Get Your Fabric On-Grain).
4. Pull it straight if it is off. UNH: if it is no more than about 1 in off, hold both sides and pull diagonally toward the shorter corner; steam pressing helps. UK pulls on the true bias while the fabric is slightly damp, then dries it flat on grain.

Some fabrics will not come straight. UNH's guide says durable-press, crease-resistant, wrinkle-resistant and wash-and-wear finishes lock the yarns in place, and UK's sheet says fabric set off-grain by heat may not be fully correctable. Seamwork says plainly that some fabrics will not get on grain, and suggests buying an extra 1/8 yd for squaring. If a print was put on off-grain, cutting on grain makes the print look crooked. Test it Check the bolt end for a finish before you buy a print you need to look straight.

Interfacing

Interfacing is a hidden layer that gives a part of a project body or support: a collar, a cuff, a waistband, a buttonhole edge, a tote's straps. NMSU's interfacing guide sorts it two ways (NMSU Guide C-208, Selecting Interfacings): by structure, it is woven, knit or nonwoven; by application, it is sew-in (stitched in with the seams) or fusible (with a heat-activated adhesive on one side, pressed on with an iron). NMSU's rule for weight is the same as the fabric or lighter, and lighter still for a fusible, because fusing stiffens. Convention

On preshrinking, read the instruction sheet that comes with the interfacing you buy, and follow it. Product-specific Keep fusible interfacing out of the washer and dryer: Washington State's bulletin and Pellon both say so; WSU explains that the washer can strip the adhesive and the dryer can set it. WSU's bulletin and NMSU's guide both suggest a fused test sample on the real fabric, washed the way the item will be washed, before you commit.

5. Flammability and children's sleepwear

Federal flammability rules exist because some clothing catches fire easily. The Flammable Fabrics Act, passed in 1953, makes it unlawful to manufacture for sale, sell, offer for sale, import or ship in commerce any "product, fabric, or related material" that fails an applicable flammability standard (15 U.S.C. §1192, Cornell LII). The Consumer Product Safety Commission has administered it since the agency was created in 1972 and has set standards for clothing textiles, children's sleepwear and other products (CPSC, Flammable Fabrics Act). Its prohibitions are tied to sale and commerce.

General clothing. The clothing standard, 16 CFR Part 1610, sorts fabrics into three classes by how fast they burn; Class 3, "rapid and intense burning," may not be used for clothing (16 CFR Part 1610). The rule exempts some fabrics from testing, which is different from exempting them from the standard: plain-surface fabrics of 2.6 oz/yd² or more (88.2 g/m², by NIST's factor), and fabrics made entirely of acrylic, modacrylic, nylon, olefin, polyester or wool, of any weight. The rule's reason is that years of testing show those fabrics consistently give acceptable results; the exemption does not make them flame-resistant. Polyester, on the exempt list, melts and drips when it burns (UGA; Colorado 4-H's burn-test worksheet asks learners why that is a safety concern).

Children's sleepwear. Two stricter standards cover sleepwear for children: Part 1615 for sizes 0 to 6X and Part 1616 for sizes 7 to 14 (16 CFR Part 1615; 16 CFR Part 1616). Sleepwear sold for them must pass flame tests, unless it is an "infant garment" (sized 9 months or smaller) or a "tight-fitting" garment that meets the rule's maximum measurements and labeling. The CPSC's business guidance for the Act summarizes these exceptions (CPSC, Flammable Fabrics Act business guidance). Both standards also cover fabric "intended or promoted" for children's sleepwear. A bolt end marked "not intended for children's sleepwear" is the seller's statement about that fabric.

The CPSC's consumer advice explains the reasoning in plain terms (CPSC, Loose-Fitting Cotton Garments as Sleepwear for Kids, 2002). Loose-fitting T-shirts and other loose clothing of cotton or cotton blends catch fire easily and burn rapidly, and the CPSC says they should not be used as children's sleepwear. Snug-fitting sleepwear is less likely to touch a flame and burns less readily because there is little air under it. The safest choices, in the CPSC's words, are snug-fitting cotton and flame-resistant sleepwear. Ask the authority

6. See it: Dana's quilting cotton See it

• 16 CFR Part 423: the Care Labeling Rule itself; its Appendix A is the glossary of care words used above. Here so you can look up any word on a label.
• UK Extension, Understanding Fabric Grain: two pages with drawings of grain, selvage and bias on wovens and knits.
• Seamwork, How to Get Your Fabric On-Grain: photographs of folding out drag lines and pulling a thread, the steps in section 4.

7. Practice: one bolt end, one shrink test Practice

Minimum: one bolt end read and recorded, the pillowcase fabric bought, a 6 in square measured before and after one preshrink, and one end squared. Time: about 40 minutes of your own work, plus a wash and dry cycle. Materials: about 1 1/4 to 1 3/4 yd of firmly woven cotton or cotton blend (more if you are buying for your own project at the same time), a ruler, a tape measure, scissors, a safety pin, a pencil, and access to a washer and dryer or a basin.

1. Read the bolt end. Write the fiber content, width and every care word, or copy them from an online listing, onto the fabric sheet with the length you buy and what it is for.
2. Buy enough length. The pillowcase pieces need 1 yd of length (USU: 27 and 9 in long, 42 in across); add USU's extra 1/4 yd or more for shrinkage, squaring and test scraps.
3. Cut and measure the square. Pull a thread or tear for a straight crosswise edge, cut a 6 in square against it, pin the lengthwise side, and measure both ways.
4. Preshrink. Wash and dry the fabric and the square together at the pillowcase's settings, and take them out of the dryer promptly.
5. Measure and record. Measure the square both ways and the full width selvage to selvage. Enter the shrink result and the width, and check preshrunk.
6. Square one end. Use the steps in squaring on grain, then fold the fabric for Cutting, marking and pressing.

8. Your sewing Your sewing

9. Check your work Check your work

Criteria

• Does the fabric sheet name the fiber content as the bolt end gives it, with percentages for a blend?
• Are the care words written exactly, not paraphrased into symbols or shorthand?
• Was the fabric preshrunk by the method the finished item will get, and does the sheet say which?
• Is the shrink result recorded both ways, with the before and after measurements?
• Is the width the one you measured after washing?
• Does one cut end follow a single crosswise yarn, and does the fold lie without drag lines?
• If anything you plan is for a child to sleep in, is it a snug-fitting style or fabric sold as flame-resistant for sleepwear?

Worked example

In Dana's fictional case: the sheet names 100 percent cotton, 44 in on the bolt, "machine wash warm, tumble dry low," preshrunk at those settings, and "6 × 6 to 5 7/8 × 5 13/16" with both percentages. Her width line still says 44 in from the bolt end. That is the one gap against the criteria: she measures across the washed fabric, finds about 42 1/2 in, and changes the width to the measured figure, which the calculators will read in Cutting, marking and pressing and Your project. Her squared end lies flat when folded. Nothing she is making is for a child.

Common mistakes

• Planning with the bolt-end width. The washed width is narrower, sometimes by more than the square suggests. Measure it.
• Preshrinking hotter than the item will be washed. It shrinks more than it would in use and can fade or felt for no reason. Match the finished item's care.
• Putting fusible interfacing in the washer. Both WSU and Pellon say not to. Follow its instruction sheet.
• Trusting a symbol over the words. The symbol may be from an edition the US rule does not name. Read the words.
• Calling a fabric flame-resistant because it is polyester. Polyester is exempt from testing, not flame-resistant, and it melts.

What is still unresolved

The shrink test measures one wash. Some fabrics keep shrinking a little after the first laundering (WSU says so of cottons), so a garment's final size is settled only by its own wear and care. Whether a print or a finished fabric can be brought on grain is settled by trying it. And whether the fabric is right for your project's stitching is settled by a sample on it in the sample book in Stitching and tension and the seams in Seams and a first piece.

10. Knowledge check and scenario

Checklist

• The fabric sheet has one row with fiber, width, care, preshrunk and the shrink result.
• The width on the sheet is the one I measured after washing.
• One cut end is squared on grain and the fabric is folded for Cutting, marking and pressing.
• I know which care words to read when a label also has symbols.
• I measured a knit's stretch or ran a burn test with the precautions. (Go deeper; optional)