Your factory has just emailed you about the crocking results, the fork position and whether your tolerances are realistic, and you've nodded along like you know exactly what they mean.
We've all been there.
Jeans come with a whole language of their own, and half of it sounds made up. This is my A–Z of the words you'll hear most when you're developing jeans, what they actually mean, and why you should care.
A is for Arcuate
The decorative stitching on the back pockets. It's one of the first things people notice from behind, so it's a big part of your brand's identity. Some arcuate designs are trademarked, so make sure yours isn't a little too close to a famous one.
B is for Block
Your brand's tested foundation pattern, the starting point for every new style. If every new pair of jeans feels like starting from scratch, you probably need one. More in what is a jeans block.
C is for Crocking
When the indigo rubs off onto something else, like your customer's white sofa or new trainers. It's tested dry and wet, and it's worth checking the results before you put dark indigo or black jeans into production.
D is for Denim
A cotton twill fabric, traditionally woven with an indigo-dyed warp and an undyed weft. That's why the inside of your jeans is lighter than the outside.
E is for Elastane
The stretch fibre in stretch denim. The amount of stretch matters, and so does the recovery: how well the fabric springs back. Poor recovery is why some jeans fit beautifully at 9am and are hanging off you by lunchtime.
F is for Fork
The point where the inside leg seams meet the front and back rise, right in the crotch. It's where a lot of fit problems start, and often where they're fixed. See how to fix the waist gap on your jeans.
G is for Grading
How your sample size is scaled up and down to make the rest of your size range. Get it wrong and your size 20 can end up looking like a completely different pair of jeans to your size 10. More on grading and your size range.
H is for Hand feel
How the fabric feels in your hand. Washes, softeners and finishes can change it completely, so always judge it on the washed sample, not the fabric swatch.
I is for Indigo
The dye that makes denim blue. It mostly sits on the outside of the yarn and leaves the core white, which is why denim fades so beautifully as it wears.
J is for J-stitch
The curved line of topstitching on the front of the fly. Small detail, big impact on how finished your jeans look.
K is for Knee
The knee width, measured at a set point down the leg. It controls the shape of the leg, especially on flares and bootcuts, where it decides where the leg starts to kick out.
L is for Leg opening
The width of the hem. Small changes here make a big difference to the silhouette, so be very clear about how it's measured.
M is for Mill
Where your denim is woven, and sometimes dyed and finished too. Sometimes your manufacturer is also the mill, and sometimes they'll source the fabric from a mill for you. A good mill can give you test reports, shrinkage information and advice on how the fabric will behave in the wash.
N is for Nickel
A metal that can be found in buttons and rivets. In the UK and EU there are rules on how much nickel can be released from items that sit against the skin for long periods, so check your trims supplier can confirm theirs comply.
O is for Ounce
Denim weight, measured in ounces per square yard. Roughly, under 12oz is lightweight, 12–16oz is midweight and anything heavier is heavyweight. The weight changes how the jeans drape, feel and fit.
P is for Patch
The brand patch on the back waistband. Traditionally it's leather, but jacron (a tough, paper-based leather alternative) is really common, and you can also use woven, printed or debossed patches. Whatever you choose, test it through your wash: some patches shrink, darken, crack or bleed, and your brand name is the last thing you want looking tired before the jeans do.
Q is for QC
Quality control. Checking the finished product against your approved sample and spec before it reaches your customers, often with an AQL inspection before it ships. More in what your returns are telling you.
R is for Rise
The front and back rise are the seams that run from the fork up to the waistband. Their length and shape decide where your jeans sit and whether there's room for a bum. It's the number one fit comment I make on jeans.
S is for Shrinkage
Denim shrinks when it's washed, in length and width, and different fabrics and washes shrink by different amounts. Your pattern needs to allow for it, so the finished jeans actually match your spec.
T is for Tolerance
How far each point of measure (POM) can be from your spec and still pass, for example plus or minus 1cm on the waist. Too loose and two customers buying the same size get noticeably different jeans. Too tight and nothing will ever pass. Your POMs and tolerances should both be clearly set out in your denim tech pack.
U is for Usage
How much fabric it takes to make one pair of jeans, sometimes called consumption. It has a big effect on your costing, and it's one of the reasons wide legs cost more to make than skinnies.
V is for Vanity sizing
When brands label clothes a size smaller than the measurements suggest, so customers feel good about the number. It's one of the reasons sizing is so inconsistent between brands. Read how to choose a base size for your jeans brand.
W is for Whiskers
The faded crease lines across the front hip and crotch that appear naturally with wear. In production they're recreated in the wash, by hand or with lasers, so your jeans look worn in from day one.
X is for X & Y
I'm going to cheat here and sneak another Y in, so it's X & Y (can you see I'm really scraping the barrel here?). When your pattern is graded, each point on the pattern moves on an X and Y axis, so the jeans grow and shrink in a controlled way across your size range. If the grade rules are wrong, the shape changes as well as the size.
Y is for Yoke
The V-shaped panel across the back, below the waistband. Its depth and angle shape the bum and have a big effect on how the back fits. A badly shaped yoke can flatten even the best bum.
Z is for Zip
For jeans, you need a semi auto-lock zip, which locks in place when the puller is flat so your fly doesn't creep down. You can also use a button fly instead. It's your brand, you make up the rules.
Still nodding along?
You don't need to know all of this to start a denim brand. That's what a garment technologist is for. Knowing the language means you can ask better questions, understand what your factory is telling you, and spot when something doesn't sound right.
If your factory has just sent you something that reads like it's in another language, send it to me.