The first 500-piece lace bustier run came back with the cups two centimeters too wide and the underwire channel twisting at the center front. The factory had followed the tech pack exactly. The problem was that the tech pack never specified the cup width at the bust point, only the overall bust circumference, and it left the channel allowance to the grader’s discretion. That omission cost six weeks and a full re-cut. If you are sourcing lace bustiers in China, the difference between a sample that fits and a production run that sells is not the lace quality. It is the set of measurements and tolerances you put in writing before the factory starts.
This is what your tech pack must specify before you sign the PO.
Cup Construction and Seam Allowance
The cup is the core of the garment. If the cup is wrong, nothing else matters. Your tech pack must specify the cup construction method: two-piece, three-piece, or molded. For lace bustiers, two-piece cups are common because they show the lace pattern with fewer seam interruptions, but three-piece cups give better projection and are necessary for fuller cup sizes. The tech pack must include a cup pattern diagram with the seam line, cut line, and notch positions marked. The seam allowance must be specified in millimeters, not fractions, because Chinese factories work in metric and a 3/8 inch allowance becomes 9.525mm, which gets rounded to 10mm, which shifts the cup. Specify 8mm or 10mm and state which.
The bust point, or nipple point, must be marked on the pattern with a cross and its position given as a measurement from the center front and from the bottom of the cup. This is the reference point for grading. If the bust point is not specified, the grader will place it based on their standard block, which may not match your sample. The distance between the bust points, known as the cross-cup measurement, must also be specified. This measurement is more important than the underbust measurement for fit because it determines how the cups sit on the body. If the cross-cup is too wide, the cups gap at the top. If it is too narrow, the wire digs in at the center front.
Underwire Channel and Wire Specification
The underwire channel is where most production problems occur. The channel is a fabric tube sewn to the bottom of the cup that holds the wire. The tech pack must specify the channel width, the channel fabric (usually a cotton-polyester blend or a power mesh), and the channel allowance, which is the amount of channel fabric that extends beyond the wire tip. If the channel allowance is not specified, the factory will leave whatever they have left over from the previous job, and the wire will either poke through or sit too far back.
The wire itself must be specified by type and size. Wires come in shapes including U-shaped, plunge, and balconette. The wire shape must be drawn on the tech pack with the wire length, wire width at the center front, and wire height at the side. The wire gauge, which is the thickness of the metal, must be specified because a thinner wire will bend and distort under tension. The wire tip coating must also be specified. Most factories use a PVC dip, but the coating thickness varies, and a thin coating will wear through and poke the wearer within a few wears.
The wire spring must be specified. Spring is the amount the wire opens when worn. A wire with too much spring will spread at the center front and cause the cups to gap. A wire with too little spring will sit too narrow and cause the cups to overflow at the top. The spring is controlled by the wire shape and the channel tension, so both must be specified. The tech pack should include a note stating the acceptable spring range, such as 5-8mm at the center front when worn.
Boning and Structure
Lace bustiers require boning to maintain structure and prevent the garment from collapsing. The tech pack must specify the boning type, boning count, boning placement, and boning attachment method. The most common boning types are steel and plastic. Steel boning is more rigid and is used for garments that need to shape the body. Plastic boning is more flexible and is used for garments that need to move with the body. For lace bustiers, a combination is common: steel at the side seams for structure and plastic at the seams between cups for flexibility.
The boning placement must be shown on the pattern diagram with the boning channel marked. The boning channel is a fabric tube sewn to the seam allowance that holds the boning. The channel width must be specified, and the boning length must be given as a measurement from the top of the channel to the bottom. The boning must be shorter than the channel by 5mm at each end to prevent the boning from poking through the channel ends. This 5mm gap must be specified because if it is not, the factory will cut the boning to the channel length, and the boning will wear through the channel ends within a few washes.
The boning attachment method must be specified. Boning can be attached by sewing through the center of the channel, sewing along both edges of the channel, or inserting the boning into a pre-made channel. Sewing through the center is the fastest method but it can distort the boning and create a visible stitch line on the lace. Sewing along both edges is more secure but it requires two rows of stitching and is slower. Inserting into a pre-made channel is the cleanest method but it requires the channel to be sewn first and then the boning inserted, which adds a step. The tech pack must state which method to use and must include a stitch diagram showing the stitch line relative to the channel and the lace pattern.
Closure and Hardware
The closure is the second most common source of production problems. The tech pack must specify the closure type, closure position, closure hardware, and closure reinforcement. The most common closure types for lace bustiers are hook-and-eye closures and busk closures. Hook-and-eye closures are more common and are used for garments that need to be adjustable. Busk closures are more rigid and are used for garments that need a firm fit.
The closure position must be specified as a measurement from the top edge and from the bottom edge. If the closure position is not specified, the factory will place it based on their standard, which may not match your sample. The closure hardware must be specified by type, size, and finish. Hook-and-eye closures come in sizes from 3×3 to 7×3, meaning 3 hooks and 3 eyes up to 7 hooks and 7 eyes. The size must be specified because a 3×3 closure on a size 34 bustier will not provide enough support. The finish must be specified because a nickel finish will tarnish and a gold finish will fade. The tech pack must state the finish and must include a note stating that the finish must withstand a 24-hour salt spray test.
The closure reinforcement is critical. The closure is under tension when worn, and if the reinforcement is not specified, the fabric will tear at the closure. The reinforcement must be specified as a fabric type, such as a twill tape or a power mesh, and the reinforcement must be specified as a measurement of the area it covers. The reinforcement must extend at least 2cm above and below the closure hardware and must extend at least 1cm to each side. This must be drawn on the pattern diagram and must be called out in the construction notes.
Lace Pattern Matching and Placement
Lace is not a solid fabric. It has a pattern, and the pattern must be matched across seams. The tech pack must specify the lace pattern repeat, the lace pattern placement, and the lace pattern matching tolerance. The lace pattern repeat is the distance between the same point in the pattern. This must be specified because it determines how much lace is wasted in cutting. If the repeat is not specified, the factory will cut for maximum yield, and the pattern will not match across seams.
The pattern repeat must be given as a measurement in both the length and width directions.
The lace pattern placement must be specified for each pattern piece. The placement must be shown on the pattern diagram with the lace pattern overlaid. The placement must specify which part of the lace pattern falls at the bust point, at the center front, and at the side seam. This is critical because if a floral motif falls at the bust point, it will create a bump under the cup. If a floral motif falls at the seam line, it will be cut in half and the pattern will not match.
The lace pattern matching tolerance must be specified. Tolerance is the amount the pattern can be off and still be acceptable. For lace bustiers, a tolerance of 2mm is standard. This must be stated in the tech pack because if it is not, the factory will use their standard tolerance, which may be 5mm or more, and the pattern will appear mismatched. The tolerance must be stated for both the horizontal and vertical directions.
Lining and Inner Structure
The lining is the layer of fabric that sits against the skin. The tech pack must specify the lining fabric, the lining cut, and the lining attachment method. The lining fabric must be specified by fiber content, weight, and finish. For lace bustiers, a power mesh lining is common because it provides support and breathability. The weight must be specified because a lining that is too heavy will add bulk and a lining that is too light will not provide enough support. The finish must be specified because a lining that is not finished will roll at the edges and create a visible line under the lace.
The lining cut must be specified. The lining can be cut to the same size as the lace or cut smaller. If the lining is cut smaller, the amount it is cut smaller must be specified. This is called the lining tension, and it is the amount the lining is pulled to fit the lace. A lining tension of 5mm is standard for lace bustiers. This must be specified because if the lining is cut to the same size as the lace, the lining will bag and the garment will not fit smoothly.
The lining attachment method must be specified. The lining can be attached at the top edge only, at the top and bottom edges, or at all edges. Attaching at the top edge only is the fastest method but it allows the lining to shift. Attaching at all edges is the most secure but it requires the lining to be hand-sewn at the bottom edge, which adds cost. The tech pack must state which method to use and must include a stitch diagram showing the stitch line relative to the lace and the lining.
Measurement Points and Tolerances
The tech pack must include a measurement chart with every point of measure specified. The measurement chart must include the point name, the point definition, the sample size measurement, the grade rule, and the tolerance. The point definition must be written so that anyone measuring the garment will measure it the same way. For example, "bust" is not a definition. "Bust, measured from side seam to side seam at the bust point, with the garment flat and relaxed" is a definition.
The tolerance must be specified for each point. Tolerance is the amount the measurement can be off and still be acceptable. For lace bustiers, a tolerance of 1cm is standard for circumference measurements and 5mm is standard for length measurements. This must be stated because if it is not, the factory will use their standard tolerance, which may be 1.5cm or more, and the garment will not fit.
The grade rule must be specified for each point. The grade rule is the amount the measurement changes between sizes. For example, a grade rule of 2.5cm for bust means that the bust measurement increases by 2.5cm for each size. The grade rule must be specified because if it is not, the factory will use their standard grade rule, which may not match your sample.
What to Do Before You Sign
Before you sign the PO, do three things. First, send the tech pack to the factory and ask them to confirm every specification in writing. If the factory does not confirm a specification, it means they do not understand it or they do not agree with it. Either way, you need to resolve it before production starts. Second, request a top-of-production sample, not a pre-production sample. A TOP sample is made on the production line with the production materials and the production operators. A pre-production sample is made in the sample room with sample materials and sample operators. The TOP sample is the only sample that will tell you what the production run will look like. Third, include a clause in the PO stating that the factory must maintain the specifications throughout the production run and that any deviation must be approved in writing. This gives you the right to reject the production run if the factory deviates from the specifications without approval.
The tech pack is not a formality. It is the contract between you and the factory. Every specification you leave out is a specification the factory will make for you, and they will make it based on their standard, not yours. The six weeks and the full re-cut that cost the first 500-piece lace bustier run could have been prevented with two measurements and a tolerance. Put them in writing before the factory starts.
What to send us
If the specifications above match what you are sourcing, send your tech pack to Orange Sea Clothing. If the pack is not written yet, sketches and a reference sample are enough to start — sample development covers the design review, fabric and trim sourcing, pattern making and the first prototype, so you see fit and construction before you commit to a production run.
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