Most sampling delays trace back to the same document. When a sample round comes back wrong, the factory usually sewed exactly what it was given, and what it was given was a tech pack with holes in it. We read a lot of tech packs in Bandung (Indonesia), and the same handful of mistakes shows up again and again, costing brands one to two weeks per extra sampling round. Here are the five we see most, and what fixes each one before it costs you a month.
Why do tech pack mistakes cost weeks, not days?
Because sampling runs in cycles. A round takes one to two weeks from brief to sample in hand, and a mistake discovered at the sample means another full round, not a quick patch. Storiginator’s rundown of the most common tech pack mistakes ranks them by how often they trigger sample rejections, and industry writing keeps repeating the pattern: The Fashion Coterie names skipping the pack entirely as the top error new brands make, and a fishbone analysis of factory delays published on LinkedIn found that simply making tech pack review mandatory before sampling cut sample rejections by roughly 45 per cent. The document is not paperwork. It is the difference between two rounds and four.
Mistake one: measurements without tolerance
A size chart that says “chest: 52 cm” looks complete and is nearly useless. Every measurement needs a tolerance, the plus-or-minus range that counts as correct, because fabric, cutting and sewing all carry natural variation. Without a tolerance, the factory aims for the middle and you judge the result against a number that was never achievable twice in a row. The fix takes minutes: add a tolerance column to the measurement chart and decide, before sampling, what deviation you will accept.
Mistake two: a bill of materials with gaps
The BOM lists every fabric, thread, button, label and added component, and Lissy Clothing’s tech pack checklist puts it among the essentials for a reason: an incomplete BOM means somebody, usually the factory, has to guess what the missing item is. Guesses become samples that are almost right, which is the most expensive kind of almost. The fix: walk the garment physically, seam by seam, and list every physical thing in it, including the ones that seem too obvious to write down.
Mistake three: stitching described as “good quality”
“Good quality stitching” is not a specification; it is a hope. CallTheStyle’s analysis of failed samples calls out vague stitching and assembly notes as a fatal pack flaw, because stitch type, density and seam construction determine how a garment is actually sewn. The fix is a construction page: one line per seam naming the stitch class, the density and any reinforcement, so the sample machinist never has to interpret intent.
Mistake four: ignoring how the fabric behaves
A spec written for a rigid woven will mislead a factory sewing a stretch knit, and vice versa. Fabric stretch percentage and recovery change how patterns must be cut and how seams must be built, which is why CallTheStyle lists ignored fabric properties among the mistakes that fail samples outright. The fix: name the fabric composition, weight and stretch in the pack, and if you are unsure how the behaviour affects the pattern, say so early; a factory that knows the fabric may move can flag it at sampling instead of discovering it in bulk. Our fabric weight guide helps with the choosing part.
Mistake five: changes after sampling is approved
The pack gets approved, bulk is scheduled, and then a message arrives: could the pocket be slightly larger? Every change after approval restarts part of the process, and HEM Apparel’s review of brand-manufacturer friction lists exactly this among the most common causes of broken production relationships. The fix is discipline rather than software: freeze the pack at approval, log any later change as a formal revision with its own timeline impact, and let the factory re-quote the effect instead of absorbing it silently.
What if you have never written a tech pack?
Start simple rather than not at all. Our tech pack introduction covers the minimum a factory needs to start the conversation, and the honest version for a first style is a sketch, a measurement chart with tolerances, a short BOM and clear construction notes. A first pack with those four sections, reviewed by the factory before sampling, beats a beautiful template full of gaps. As styles multiply, the pack grows with them, and the habit of writing it properly becomes the fastest part of the whole process.
The economics close the argument: an extra sampling round costs one to two weeks and a sample fee, and the cost per piece breakdown shows where that sits inside a 500-piece budget. An afternoon spent fixing the pack is the highest-paid afternoon in most sourcing calendars, and the lead times guide shows exactly what a saved round does to a launch date. For a small brand, one avoided round is often the difference between launching with the season and launching after it.
What order makes a pack easy to write?
The same order the garment is built in. Start with the physical walk-through and write the BOM, because everything else references those materials. Then the measurement chart with its tolerance column. Then the construction page, seam by seam, now that the materials are named. The sketch comes last as the map that ties the pages together, and labelled photos can support it but never replace a drawing with measurements on it. Assemble it this way and the pack writes itself in an afternoon; assemble it sketch-first and the gaps stay invisible until a sample exposes them.
Tech pack questions from buyers
Do I need professional software to write a tech pack?
No. A clear spreadsheet and labelled sketches cover the essentials for a first style. What matters is completeness and tolerances, not the tool that produced it.
Who fixes the tech pack, the brand or the factory?
The brand owns the pack; the factory reviews it. A good factory flags gaps before sampling, exactly the review step behind the 45 per cent rejection reduction in the LinkedIn case study, but the decisions stay with the brand.
How long should a tech pack take to write?
A first simple style: a focused day, once the measurement chart and BOM are walked through physically. Later styles get faster because the structure repeats.
Can a factory write the tech pack for me?
Factories can develop patterns and spec from a reference sample, and many do, but the design intent and tolerance decisions belong to the brand. Share what you have; a factory that asks questions before sewing is a good sign.
What if my factory finds a mistake in the pack?
Thank them and fix it formally. A factory that reviews before sewing and questions what looks wrong is protecting your sample round, and a correction logged before sampling costs nothing compared with the same correction after it.
Related Articles
- What Is a Tech Pack? Do You Need One to Start Production?
- Garment Sampling Explained: Why Samples Matter First
- Garment Production Lead Times: What to Expect
- Tech Pack Mistakes That Delay Sampling (World KNK)