Published Jan. 2020 | Updated Oct. 2024

The dreaded cracking on your painted denim is frustrating after hours—or days—painting a masterpiece on your denim jeans or jacket.

Luckily, cracking in painted denim is avoidable!

Read on to find out what causes cracking and how you can stop it from happening to your painted denim before it starts.

What is Cracking?

It might seem like an obvious question with an obvious answer, but knowing what cracking actually is in relation to painted denim is important so you can avoid it!

Cracking is what happens when dried paint splits between the grooves in denim. Acrylic paint is resin and pigment; and when mixed with fabric medium and heat-set, it becomes plastic!

While painted denim is slightly flexible, especially when painted with fabric medium and heat set, it does not love to be pulled apart or stretched.

Acrylic paint mixed with fabric medium adheres to the surface of the denim once dried.

Denim fibers can move, pull apart, and stretch (some more than others!). When the fibers are pulled apart, the acrylic paint that is attached to those fibers can break apart, aka crack, because it cannot move the same way the fibers of the denim do.

What Causes Cracking in Painted Denim?

There are a few things that can cause cracking. Knowing and understanding them all will give you a good chance of avoiding cracks in your painted denim!

1. Stretchy Denim

Based on my experience, I believe that the main cause of cracking in painted jeans is denim fibers being pulled apart when the denim is stretched.

Jeggings are a no-no when it comes to painting on denim.

While paint can stretch somewhat, and fabric medium and heat setting helps it stretch even more, it cannot stretch as much as stretchy jeans.

For this reason, I recommend always painting on sturdy denim — 100% cotton denim is best. If there’s elastic in the denim, I would avoid painting on it.

A few brands that have 100% cotton denim:

Some stretch is okay, but you will need to take precautions to avoid having your painted denim crack.

2. Low-Quality Paint

Another reason your painted jeans might crack is if you’re using low-quality paints.

I dive deeper into paint quality in my Paint and Supplies for Denim Painting post, but I’ll summarize it here.

High-quality acrylic paints contain just pigment and resin – that’s it!

Low-quality, cheap paints can contain other fillers that reduce the opacity and overall quality, plus have a lower percentage of pigment.

These low-quality paints may peel and crack when painted on denim because the fillers in them don’t stick as well to the denim.

3. Too Much Paint

Take it easy on the paint! Have you ever left a blob of paint out and let it completely dry? Sometimes it cracks because it shrinks as the moisture leaves it and it dries out.

The same thing can happen when you paint too thick.

The layer on top dries out faster, while the layer underneath takes longer. The top layer shrinks, but the layer underneath doesn’t, causing the top layer to crack before the bottom layer can completely dry.

This could also be due to low-quality paints. I have not had this experience with the paint brand I use since they do not contain any fillers.

4. Using Too Much Water

One of my theories about the causes of cracked painted jeans is the overuse of water in your acrylic mixes.

Acrylic paint IS water-based, which means you can add water to it to make it thinner.

This works for painting on traditional surfaces like canvas or paper, but not as well for painted denim.

You can use a tiny amount of water if you need to, but don’t use too much. If you need to thin your paint more, try using more fabric medium.

5. Not Heat-Setting

Your painted denim may be cracking because it was not heat-set.

I have one jacket that I painted a base layer of white on and then put away to paint at a later time. The paint became brittle and cracked — even without stretching!

My jacket was left for months with just the base layer and NO fabric medium (before I discovered it).

You don’t need to worry if it’s been a couple of weeks or if you used fabric medium.

Heat-setting only needs to be done at the end when you’re completely done with your painting.

I love my tiny travel iron for heat-setting!

Confused about heat-setting? Read my How to Heat-Set blog post to learn all about it!

How To Avoid Cracking

The best thing you can do is avoid cracking in the first place by following best practices for painting on denim!

Cracking can’t easily be fixed once it happens, so preventing it from happening in the first place is ideal.

1. Use Fabric Medium

Fabric medium is the key ingredient to painting on denim! I didn’t discover it until I had been painting jeans for one year.

It’s not a deal breaker if you paint denim without it, but it will significantly help prevent cracking, peeling, or overly stiff denim.

Fabric medium gives your paint that extra stretch it needs to stop it from breaking when the denim fibers stretch and move.

I have a full guide all about fabric medium and how to use it on painted denim!

2. Use High-Quality Acrylic Paints

It may sound repetitive to mention this agian, but it is important!

Even when I didn’t use fabric medium (for the first 1.5 years I painted denim), I never had an issue with cracking. I attribute this partly to painting on sturdy denim, but mostly to the high-quality paints I use.

My guide to Paint and Supplies For Painted Denim has all the info on which products I use and why!

3. Heat-Set Your Painted Jeans

Another repetitive topic, but also important!

Heat-setting makes your painting permanent and turns that acrylic paint into an even more durable plastic.

If you aren’t heat-setting once you finish a denim painting, even sturdy jeans and high-quality paints won’t necessarily stop your jeans from cracking.

This is a step you cannot skip!