TL;DR
A first sample that comes back wrong almost always traces to something missing from your tech pack, not a factory error.
Flat sketches must be black-and-white technical line drawings with callout annotations. Fashion illustrations tell factories nothing about construction.
A bill of materials without Pantone codes, weights, and per-unit consumption is not a BOM. It is an invitation for the factory to substitute materials on your behalf.
Measurements without tolerances give factories no QC standard and no documented basis for rejecting a garment that measures wrong.
Missing size grading forces factories to apply their own grade rules, which may not match your fit intent.
Version confusion, meaning no revision date and no change log, is one of the most common causes of bulk errors that happen AFTER a correct sample is approved.
A production manager opens a new tech pack. The first thing they do is flip to the flat sketches. If those are unclear, the pack goes into a question pile before anyone reads page two. If the sketches hold up, they move to the BOM, and that is where most small brand packs fall apart.
This happens dozens of times a week at any active factory. Most brands never see it because the questions arrive by email and feel like normal back-and-forth. They are not. They are a signal that the pack did not clear the first internal review on the factory side.
The factory is not being slow. They are waiting because your document left something out. Every gap gets filled one of two ways: they ask you, which costs a round, or they make a call, which costs you a sample. Neither is a factory problem. Both trace back to the tech pack.
Below are the eight things production teams actually need from your document, at the specific stage where they need them.
Why Most Tech Packs Fall Short Before Sampling Even Starts
A tech pack does not fail because it is too short. It fails because it is missing specific information at the exact stage where the factory needs it. Costing needs a complete BOM. Cutting needs graded measurements.
Sampling needs construction callouts that map to sketches. QC needs tolerances. Shipping needs packaging and labeling specs.
When any of those pieces is missing, the factory has two options: ask or assume. Neither outcome moves your production forward on your terms.
1. Technical Flat Sketches, Not Fashion Drawings
What factories see: A Canva render, a fashion sketch, or a single front-view illustration. Shading hides seam lines. A front-only view leaves back construction entirely up to interpretation.
What you should send: Black-and-white line drawings for front, back, and interior views, with leader lines pointing to every structural detail. Seam type, topstitch width, bartack placement, zipper stop point, pocket depth, and lining attachment.
If a detail is structural, it gets a callout. If you export sketches from Illustrator, verify that the annotations travel with the image and are not sitting in a separate notes field.
2. A Complete Bill of Materials, Not a Fabric List
A BOM is not a list of fabrics. It is a complete accounting of every component, with enough detail that a sourcing team can procure each one without asking a follow-up question.
What factories see: "Main fabric: 100% cotton twill, navy." No weight. No Pantone. No per-unit consumption. If they source a 7oz twill instead of the 10oz you had in mind, your jacket drapes differently, and there is no document that says it is wrong.
What you should send: Every fabric, lining, interlining, thread, button, zipper, label, elastic, and packaging material.
Each line item needs a component name, Pantone or hex reference, weight or spec, supplier code or approved source, and per-unit consumption. Gaps in the BOM are not mistakes that factories correct. They are decisions factories make for you.
3. Measurements With Tolerances, Not Just Target Numbers
Every measurement needs a plus/minus tolerance column. Without it, your factory has no documented QC standard at any production stage.
What factories see: "Chest: 52cm. Body length: 70cm." No acceptable variance. When a garment measures 53.5cm at QC, the factory has no basis for deciding whether it passes or fails. The call becomes subjective, and subjective QC produces inconsistent results across a run.
What you should send: A points-of-measure table with a tolerance column for every measurement. Tolerances typically run between ±0.3cm and ±1cm, depending on the component and fabric behavior.
A heavy fleece and a cotton poplin do not behave the same in production, and the tolerance should reflect that. Brands that include complete tolerance columns consistently need fewer sampling rounds to reach an approved garment.
4. Full Size Grading, Not Just a Sample Size Spec
If your tech pack has measurements for one size only, it is not ready for production.
What factories see: A measurement table for size M. To produce your full run, the factory needs to know how every measurement step changes between sizes. Without grade rules, they apply their own standard grade, which may have nothing to do with your fit intent.
What you should send: A graded spec table with your base size measurements and the grade increment for each size across every relevant point of measure.
A wrong increment at the waist compounds differently across each size, and by bulk production, the error is in every size except the one that was sampled.
5. Construction Callouts That Map Directly to the Sketches
Construction notes and flat sketches are only useful when they reference each other directly. When they live in separate sections with no connection, the factory has to cross-reference two parts of your document to answer a question that one annotated drawing should resolve.
What factories see: "Double-needle topstitch on side seams" in a notes field, with no callout on the sketch showing where the side seam ends and the hem begins.
What you should send: Every construction note mapped to a specific sketch callout. Stitch type by location, seam allowance at each seam, topstitching distance from the seam, reinforcement points at pocket corners and strap attachments, interfacing placement, and lining attachment method. The note lives on the drawing, with a leader line pointing to the exact location.
6. Version Control the Factory Can Actually Trust
Outdated files cause more bulk production errors than most brands realize. A correct sample gets approved, a late-stage spec change gets made, and the factory sews bulk from the file they already had because no one confirmed a new version was sent.
What factories see: "Jacket_FINAL_v3_ACTUALFINAL.pdf" with no revision log. The factory may be holding three or four versions with no signal about which one is current.
What you should send: Every file shared with a factory carries a revision date, a version number, and a brief change note. The version the factory is working from should be unambiguous, every single time.
7. Packaging, Labeling, and Compliance Details
Most small brands forget that the tech pack covers how the garment leaves the factory, not just how it gets sewn. Factories cannot ship without care labels, fiber content labels, country-of-origin labels, hang tags, poly bag specs, folding instructions, and carton pack ratios.
What factories see: A complete construction spec with no packaging section. Production pauses for answers, or the factory defaults to their standard, which may not meet your market's compliance requirements.
What you should send: Brand label placement and attachment method, care symbol sequence, fiber content and regulatory format, country-of-origin requirement, hang tag placement, poly bag dimensions and closure type, folding method, and carton pack ratio by size. This adds less than one page and eliminates an entire round of production questions.
8. A Format the Factory Can Actually Work From
The document format is part of the spec. Factory floor teams reference tech packs on shared computers, print them for cutting room use, and need to navigate sections quickly.
What factories see: A multi-tab Excel file where formatting has shifted between your machine and theirs. Or a PDF where images are compressed into illegibility. Excel was not built to anchor images to cells reliably, and formatting drifts every time the file moves between machines.
What you should send: A structured document where sections are clearly separated, sketches are print-quality, and every annotation is legible at any zoom level. If you are still building packs from Illustrator exports dropped into Excel, the layout drift and version control problems stay with you permanently. A dedicated tech pack editor fixes them at the structural level.
The Bottom Line
Every gap in your tech pack is a decision the factory makes for you. Most will not match what you had in mind, and you will not know which ones were wrong until the sample or the bulk arrives.
A factory that receives a complete pack with tolerances, grading, construction callouts mapped to sketches, and a clearly versioned file has everything needed to quote accurately and sample correctly on the first send. That is the actual goal of a tech pack, not documentation for its own sake.
Techpack Builder is a dedicated tech pack tool that brings your imported sketches, BOM, spec tables, and callouts into one structured workspace and produces a factory-ready export that is consistent and versioned across every style. Free to download on Mac and Windows, no signup required.
FAQ
Why does my factory keep sending questions even after I send a tech pack?
The most common causes are missing tolerances, no size grading beyond the sample size, and construction notes disconnected from the sketches. Each one forces a question round before the factory can move to the next stage. Address all three, and most packs move to quoting without a back-and-forth.
Do I really need tolerances if I am only making small quantities?
Yes. When you are making 100 units per style, a 15% QC failure is 15 garments you cannot sell. Without documented tolerances, you have no contractual basis for having them corrected or rejected. Tolerances are not a scale requirement. They apply to any production volume.
My first sample was approved. Why did Bulk come back wrong?
Version control is the most likely cause. If a spec change was made after sample approval and sent via email rather than through an updated file, the factory likely sewed bulk from the approved sample version. Every post-approval change needs a new version number, a dated change log, and explicit confirmation that the updated file is current before bulk cutting begins.
Can I build a factory-ready tech pack without a technical designer?
Yes, with caveats. Tolerances and grading are where non-technical founders most often go wrong, because both require understanding how garments behave across fabrics and sizes. The rest, including flat sketches, BOM, construction callouts, labeling, and packaging, can be built by a founder who knows their product well. A structured template reduces the risk of missing sections entirely.
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