Understanding Denim Fabric for Dressmaking

Denim is such a classic fabric and really versatile for so many everyday wearable types of garments, so if you haven’t sewn with it yet, I’m sure you will very soon!

Once you get into it, the term denim covers a wide variety of fabrics with different thicknesses and uses so it worth making sure you have the right kind of denim to get the garment you want.

In the third part of my fabric focus series I’m going to breakdown and explain that different types of denim, how to work with them and how to wash them, along with lots of lovely pattern suggestions.

To hear me chat about the fabrics and see them up close check out my latest Youtube video

What is denim and how is it made?

Denim fabric is traditionally made from cotton and is woven in a way that creates a diagonal ridged texture on the surface. This type of weave is called a twill weave and is what makes denim thick and hardwearing.

It’s common now for denim to be made from a mix of cotton and polyester to help control shrinkage and wrinkles. Some fabrics also have a stretch fibre such as elastane or spandex to add stretch for more fitted styles of garments. This is typically around 2-3%. The percentage of (physical) stretch a fabric has can be calculated in the same way I explained for jersey fabric in the last post using the printable diagram from Megan Neilsen (link here).

Typically when classic blue coloured denim is made the threads going in one direction have been dyed blue and the other threads are left white. This is what can give the two-tone appearance to denim.

Of course you can get other colours of denim but various shades of blue are the classic, common ones so sometimes other fabrics that have that are a similar colour get called denims too even though they don’t have that diagonal twill weave.

How to wash and care for denim

The most important thing to know about denim in terms of washing and wearing it is that it will fade in colour and ‘break in’ and soften over time. It will shrink a bit too. Around 5% is pretty common but it can be up to 10-15% for 'raw' denim, which is denim that has not undergone any treatment after it has been woven in the first place.

Here is a new and worn in comparison of the same pair of jeans and you can see where the denim has naturally faded at certain points. This is just a normal natural feature of denim and part of the look you get with garments made from this fabric.

The fading and wearing in of denim can vary depending on the quality of the fabric and the particular dying process it’s gone though during manufacturing. Having done a bit of research on it in the past and experimented with at home dye fixing methods like soaking in vinegar, they don’t make any noticeable difference and if the fabric dye hasn’t been fixed onto the fabric when the fabric was actually manufactured then it will just fade and there isn’t much you can do about that.

Always pre-wash your denim. I typically wash mine at 40 degrees on a 1200 spin cycle with 3-4 rinses. To go a little easier on it you could wash at 30 degrees, lower the number of rinses and reduce the spin cycle. I just like to make my laundry life easy and wash everything together and I like washing at 40 degrees most of the time.

If you are washing a very dark coloured fabric that is very saturated with dye, its common after pre-washing to notice some faint light lines on your fabric. This is just where the dye has started to wear off during the prewash. I usually find that by the time I have made my garment and worn and washed it a few times as a made up garment, it all blends in and just adds a nice character to it.

Tips on working with denim

Pressing and ironing – if you are working with thicker denim then pressing and ironing the fabric as you progress though your project will really help to get a nice crisp finish. For areas where there are lots of layers and its all a bit bulky then a wooden clapper can help. Once you have pressed and ironed the fabric and its hot and moist with steam, press the clapper on the fabric to set it and make it much flatter.

Dealing with the stretch in denim – when you work with denim that is stretchy you still treat it like any regular woven fabric. So normal straight stitch seams are fine.

The main thing to bear in mind is that the fabric will stretch and bag out a bit as you wear it. This is because fabrics can have different amounts of recovery. This means once the fabric has been stretched, how well does is go back to its original shape. A good example of this is getting baggy knees in a garment. This will happen when fabrics don’t have good recovery. It usually takes a wash to get them back to their original shape.

When I’ve made jeans before using stretch denim I’ve made sure at the fitting stage that they are really nice and snug and well fitted as I know that as soon as I start wearing the jeans the fabric will relax and stretch out a bit.

Why choose denim fabric for dressmaking?

• Even if you haven't sewn with it before there is a pretty good chance that you have garments made from denim - so you know you'll get a lot of wear out of anything you make!
• It's pretty easy to work with, even the lighter weight denims are easy to control and sew with. The press well and are easy to handle.
• If you've ever considered making jeans before I'd highly recommend it. I've done several posts on jean making before and it really wasn't as hard as I thought it would be and gave my sewing confidence a massive boost. As someone who wears jeans a lot it's really lovely to get so much wear out of something I've made!
• It's a really versatile fabric and you can make a huge variety of garments with it, there really is something for everyone!

Types of denim and what to do with them

I’ve tried to keep this list as relevant as I can for the home dressmaker and the common types of denim fabrics that are available to buy from fabric shops.

There are two main considerations when it comes to choosing the right denim fabric for your project

The thickness or the weight of the fabric. Weight in ounces oz is most commonly ranges from 4.5/5oz up to 20oz. The number is calculated by weighing one square yard of the fabric. This is the imperial way to measure weight. You may also come across the metric measurements of grams per square meter (GSM). In the shop, most of the time we know the weight in ounces so you’ll find this is fairly common to come across. Obviously the higher the number the thicker sturdier the fabric will be.

Denims of different weights can be stretch or non-stretch. Check the fibre content and whether it contains a stretchy fibre such as elastane or spandex. It's likely your pattern will call for a stretch denim if its needed - for example skinny or fitted jeans.

4.5oz - 8oz light weight denim

This denim is the softest and most pliable type of fabric. It’s comfortable to wear straight from the offset and great for shirts, dresses, skirts and some tops.

Chambray fabric

Although they aren’t strictly denim I wanted to include these fabrics in this post two as they are also suitable for the same patterns that light weight denims are. Chambrays have the regular in/out grid like weave, but just like denims, one of the threads is blue and one of the threads in white – again giving the classic two tone denim look.

I usually find chambrays tend to be made using a thicker thread so the texture can seem a little more irregular and natural, which gives them a lovely character.

Often the fibre content is a mix of cotton/linen or cotton/rayon or rayon/linen. They are a bit more prone to shrinking so pre-wash is a must and definitely air dry rather than tumble dry.

8oz-11oz light - medium weight denim

These fabrics feel more sturdy and will hold their shape more than the lighter weight ones. This makes them more suited to trousers, skirts, overalls and dungaree style dresses.

Depending on the style of the garment and what the pattern calls for you may or may not want stretch in the fabric. If the garment is more fitted then you’ll need stretch.

12oz – 20oz heavy weight denim

This is the type of denim that can pretty much stand up on its own. It’s really thick and sturdy and very hard wearing. It can feel very stiff when you first work with it and wear it but over time it will soften and fade. It’s best suited to looser styles of garments like baggy boyfriend style jeans. You could use it to make a pinafore or dungaree style dress and its great for bags as well.