Alter your patterns... without too much pain

You know as well as I do that buying a pattern, even your size, doesn't necessarily guarantee a good fit. And that's assuming the pattern you bought is spot on what you want style wize. Which is rarely the case in the world of cosplay. Because you have an EXTRA precise design in mind, and you want to reproduce your favorite character as faithfully as possible.

Well, the pattern you have in hand is probably a pretty-cool-but-not-quite-perfect style. Right?

So, let's talk about alteration. So that you know the right techniques to transform your patterns. And so you don't lose too much hair the next time you need to make changes to a pattern.

Know why you are making changes to your pattern

If you want to change the style you won't make your changes the same way than if you want to adjust the size.

Say you want to shorten a skirt…

It sounds simple, right? And most times, it is. But there are still a few things to know.

If you just want to make a skirt shorter because you have a long skirt pattern and you want to make a shorter skirt. Go for it. It's usually ok to just calculate the lenght you want and trace your hemline.

altération - ajustement patron, raccourcir une jupe

On the other hand, if you have the same long skirt but you want to make it shorter because you are shorter than average, you'll want to keep the proportions of the skirt. Remember in my very first article when I told you about the importance of a good fit and proportions.

In the case of our skirt here, you want it to stay snug at the thighs and widen from the knees. Not just mid-calf (if you're petite, I'm sure you understand exactly what I'm talking about, right ?). It means that you're gonna to want to reduce the part of the top of the skirt AND the part of the bottom. That way, you won't touch the section around the knees. You follow me?

altération - ajustement patron, longueur de jupe

Be careful not to modify key elements

Ok. Say you want to make a t-shirt wider. But just the width. Not the sleeves, not the neckline. You have 2 options (actually, you have thousands - sky's the limit - but let's simplify to 2):

  • You may want to make the t-shirt wider so that it looks loose all over (low armscyes, and everything).

altération - ajustement patron, élargir un chandail

  • Or you may want a t-shirt that looks wide, while keeping a good fit at the shoulders.

altération - ajustement patron, largeur de chandail

Either way, it's best to make your adjustment where it isn't to much going on.

Avoid widening in the center, because you'll make your neckline bigger too. And avoid expanding on the sides, because you'll change the size of your armholes (and your sleeves won't fit anymore).

By widening across the shoulders (where you just got straight lines), you don't change the to much around. Just the width of the sweater. And you can modify it however you want.

Above all, you have to really understand what you want to change. And most importantly, what do you want to keep as is.

Don't forget the seam allowances​​

Most store bought patterns have seam allowances included. So, you have to think about those seam allowances when you work.

Let's simplify my skirt for the example. Say you wish there was a seam in the front. Maybe you want to divide the center piece into 2. Don't forget to add seam allowance. Because if you don't, it'll be like reducing the size of the skirt. You follow me?

altération - ajustement patron, pièces et valeurs de couture

And that goes for all the details you change. So if you're thinking about changing your pattern quite a bit. Like adding a big bunch of seams and yokes, putting some pieces together... You know, big alterations. You might want to take all the seam allowance off your pattern. That way, you won't have to wonder where to add seam allowances and where to remove them... It's really less confusing.

Personally, I always (or almost) work with patterns without seam allowance. And I trace those directly on my fabric when cutting (I'll give you some tips on that next time).

Make a mock up

I wrote about that in my article on measurements. Even with the best measurement in the world, there's no guarantee your pattern will hve the perfect fit. That means it's better to test it.

For that, you can make yourself a mock up. That is to say a prototype of your garment in an inexpensive fabric, just to check the size, the fit, the proportions, that sort of thing.

I know. You're gonna to tell me it's long, and you don't have time. But honestly, you're gonna to save on the long run. Making a mock up will allow you to test the overall look and fit of your garment, without using your "real fabric" (which, maybe, was kinda expensive).

And when you get to actually sew your costume, not only will you be more sure about the final look. But, you'll also be better equipped to assemble it and you'll know where you're going (because it's gonna be the 2nd time you've done it).

With experience, I have less need for mock up. However, when I work with really fancy fabrics or with real leather, I still do.

I can correct the fit more easily. But also the lines and the seams.

altération - ajustement patron, corriger les lignes et les découpes

There's so much more to talk about. But I think it's a good base to start.

Patterning is kind of a pretty big thing, and it can seem complicated sometimes. But if you take your time, or if you don't skip any step, you should be fine.

I swear.

Talk to you soon.

Until then… Keep on crafting!



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