How to Turn a Tech Pack into a Production Specification

Most programmes stop at the pack. The pack is good enough to get a sample made, and because the sample is approved in writing, it becomes the reference by default. That works until something is disputed, at which point the dispute turns on a document that never said what tolerance applied.

The specification is not a longer document than the pack. For most bag programmes it is the same pack with four sections added, and it is written once per style rather than once per order. The work is front-loaded and it is not large.

What it buys is that the purchase order, the inspection and any later claim all read the same document. A pack says what was intended; a specification says what was agreed, and only one of those is enforceable.

What Is the Difference Between a Tech Pack and a Specification?

A pack is addressed to the sample room and it answers what to make. A specification is addressed to the line, the inspector and the buyer, and it answers what to make, how it will be checked, and what happens when it does not meet the check. The audience changes and the document changes with it.

The practical difference is the verb. A pack uses describe: the panel is 430 mm, the strap is polyester, the seam is bound. A specification uses measure: the panel is 430 mm plus or minus 5 mm measured flat; the strap is polyester to a stated breaking strength; the seam is bound and holds a stated figure.

The second difference is that a specification has a revision record and a pack usually does not. Without one, two people can be working from two versions of the same document and neither can prove which is current.

What Gets Added When a Pack Becomes a Specification?

Four sections. A tolerance block, listing every measurable dimension with its band. A testing block, listing every claim with the method and the limit. An inspection block, giving the sample size, the level and the AQL. And a revision block, giving the version, the date and what changed.

Everything else in the pack carries over unchanged: the materials list, the construction note, the artwork, the BOM, the packing. A specification is additive rather than a rewrite, which is why it is worth doing on every style rather than only on the difficult ones.

There is a fifth section that some programmes add and most should: a sign-off block, naming who agreed what and when. Where a programme runs through several people on the buyer side, a sign-off block is the difference between an agreed specification and a file that several people have edited.

How Are Tolerances Written Into a Specification?

As a band on every measurable dimension, with the method and the condition stated alongside. A dimension without a method is a measurement waiting for an argument: a soft bag measured flat and the same bag measured stuffed differ by more than most tolerances.

The band should be achievable rather than aspirational. A tolerance tighter than the process can hold is not a specification, it is a rejection rate, and it shows up as a failed inspection on a product that is perfectly usable. Where a dimension matters to the customer, tighten it; where it does not, state a band the process can hold.

The third field is what happens at the edge. Every tolerance block should say whether a unit at the limit is accepted or rejected, because otherwise the limit is the start of a discussion rather than the end of one. Stating that the limit is inclusive closes it.

How Are Test Methods and Limits Written?

As a method number, a condition and a limit, in that order. A claim that the shell meets a tensile figure is three fields: the standard the test is run to, the condition it is run under, and the figure it has to reach. A claim with only the third field is unfalsifiable.

The standards most bag programmes need are few. Tensile properties of fabrics are covered by ISO 13934-1; seam properties by the companion methods; stitches and seams by ASTM D6193; coated fabrics by ASTM D751; colourfastness by the AATCC methods, including AATCC 16 for light. Naming the number is most of the work.

The limit should be written as a minimum or a maximum rather than as a target, and it should say how many specimens. A test with no specimen count is a test whose result can be selected, which is not the intention but is the effect.

How Is the Inspection Criterion Written?

As a standard, a level and an AQL, with the defect classes defined. ISO 2859-1 at General Inspection Level II with an AQL of 2.5 is the usual setting for a bag programme, and it is worth writing the three fields out rather than writing an AQL alone, because a level changes the sample size.

The second part is the defect dictionary, and it is the part most programmes skip. A major defect and a minor defect are classifications made by the inspector unless the specification makes them, and two inspectors will not classify the same mark the same way. A short list of what counts as critical, major and minor removes that.

The third part is the acceptance number. Where the AQL and the sample size are stated, the accept and reject numbers follow from the standard; where they are written out as well, an inspection result can be read without looking anything up.

How Are Packing, Marking and Labelling Specified?

In one block with five fields: how each unit is packed, how many go in a carton, the carton dimensions and grade, the shipping mark, and the labelling on the product. Packing is where a good product gets damaged, and it is the section most often written after the first shipment rather than before it.

The carton grade is worth stating as a construction rather than as a feeling: a wall count and a board grade, with the closure method. A carton specified as strong is a carton that will be the weakest one available at the time of the order.

The labelling block is where compliance lives. A country-of-origin mark, a fibre content label, a care instruction and any market warning are requirements rather than preferences, and they belong on the specification rather than on the artwork, because they are checked at import rather than at inspection.

How Does Revision Control Work on a Specification?

One version number, one date, and a line saying what changed. A specification at revision C that does not say what changed from revision B forces everybody to compare the two documents, and nobody does.

The practical rule is that a revision is issued rather than edited. The previous version stays on file, the new one carries the number and the note, and the BOM and the pattern carry the same number. Where three artefacts carry three different revisions, the line will use the wrong one.

The third rule is the one that gets broken: a revision after the sample is approved is a change to the product and it has to be re-sampled where it changes anything measurable. A specification revised after approval without a re-sample is a specification bulk cannot be held to.

Who Signs What and When Does a Specification Freeze?

The buyer signs the specification and the supplier signs the sample, and both happen before bulk. The specification is what bulk will be measured against; the sample is what bulk will be compared against. Where the two disagree, the freeze is the moment to find out.

The freeze point is written sample approval. After that, any change moves the delivery date, because bulk runs 35-50 days from that date and a change to the specification during bulk is a change to the schedule rather than to the document.

The useful discipline is to say so on the document. A specification that states its own freeze point and the consequence of a change after it prevents the conversation where a change is requested in week four and the date is expected to hold.

How Does the Specification Reach the Purchase Order?

As a referenced revision number on the order. The purchase order should name the style, the specification revision it is placed against and the sample revision it has to match, which is three fields and it is what makes the order enforceable.

The second connection is the commercial terms. Incoterms 2020 defines where risk and cost transfer, and the order should name the rule rather than describe it, because the three-letter rule and a sentence describing it are not the same thing in a dispute.

The third connection is the inspection clause. Where the order names the standard, the level and the AQL, the inspection is a contractual step rather than a favour, and the result of it has something to be measured against.

What Does the Specification Do for a Second Run?

It removes the re-development. A second run placed against a named specification revision and a held approved sample needs no new sampling, because what has to be made is already defined and what it has to match is already held. Where a programme has neither, the second run is quoted as though it were the first, and it is very often sampled as though it were the first as well.

The second thing it does is make a substitution visible. A material changed on a second run shows up as a weight difference, as a thickness difference or as a test result outside the stated limit, and all three are measured against the specification rather than argued about. Without the figures, a substitution is a matter of opinion between two people who have both handled the bag.

The third is that it makes the price reviewable. A second run quoted higher than the first can be taken apart line by line against the BOM revision the first run was placed against, and the difference attributed to a material, a quantity or an exchange rate. That is only possible where the first run had a numbered specification to compare against.

One caution is worth stating. A specification is only as good as its revision discipline, and a specification that was revised three times during the first run without a record is little better than no specification at all. Where the first run was messy, the second run is the moment to reissue the document cleanly rather than to carry the confusion forward. Reissuing one clean document at the start of a second run costs less than a single disputed inspection.

What Is the Short Rule for Turning a Pack Into a Specification?

Add four blocks rather than rewriting the pack: a tolerance on every measurable dimension, a method and a limit on every claim, an inspection criterion with a defect dictionary, and a revision record.

Then reference it on the order. A specification that is not referenced anywhere is a document rather than an agreement, and the difference shows up the first time something is disputed.

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