Fabric Marking Pens 101: The Science Behind Water-Soluble and Heat-Erase Markers

Have you ever wondered about the magic behind your favorite marking tools? What’s really going on when you spritz a fabric marking line with water or iron away a design drawn with a Frixion pen? We’re diving into the science behind two of quilter’s favorite fabric marking tools - to learn what really happens to the ink on your fabric. 

Let’s geek out - quilter’s style.

Water-Soluble Fabric Markers

Water-soluble makers are a staple in many quilter’s toolkits. They’re perfect for marking out quilt designs, labeling pieces, or even marking seam allowances. But what really happens when the ink is saturated with water?

Marker Ingredients

These markers typically use a water-based ink that includes: 

• Dyes or pigments: these provide the color

• Solvents: mostly water, which makes them less toxic and easy to remove

• Humectants (moisturizers): like glycerin, to keep the ink from drying out

• Surface-Active Agent: these help the ink spread evenly on the fabric and then later attract to the water to dissolve

Now down to the Science

Given the ingredients that make up these markers, the water-soluble ink tends to only sit on the surface of the fabric fibers. The ink is bound to the fabric through weaker forces like hydrogen bonding (think tape instead of permanent glue) rather than creating a permanent chemical bond at the molecular level. This is the work of the surface-active agent which helps lift and suspend the ink particles over the fabric fibers, and later allows them to be wiped away when washed with water.

The dyes used in these markers are hydrophilic - meaning they love water! Once the ink molecules are rinsed, spritzed or soaked the dye quickly bonds to the water and washes away! The ink is easily diluted as the water reaches the fibers of the fabric and the “tape” is ripped free allowing the dyes to wash away in the process.

So What Does This Mean?

Water-soluble fabric markers are a great way to temporarily mark your fabric and be able to wash away the ink when you’re done. Knowing that the dye is completely removed from the fabric as it dilutes into the water makes this type of marking tool an excellent choice for stenciling. 

As with all marking tools, it is best to test your fabric and marking tool first. It is possible to have different fabric fiber types or dyes react differently, so test the fabrics on your project before beginning. 

Things to Note with Water-Soluble Fabric Pens

• The ink dissolves, but be careful not to heat-set the marks by ironing. Heat can sometimes make the dye more permanent to the fabric. 

• It’s always best to rinse the dye off as soon as you are finished with the marks. I have had success in leaving the pen marks on my quilts for several months at a time (kids and life can get in the way of my quilting) but if you are concerned, be sure to rinse immediately.

• Cool or warm water usually helps dissolve the ink best - avoid using hot water.

• Adding a little baking soda to cool water can help balance the pH in the water which also might help the ink more thoroughly wash away from the fibers.

My Marking Tool of Choice for Stenciling

When it comes to stenciling my quilts, water-soluble pens are my favorite. Having the ink wash completely out of the fibers of fabric, paired with the fact that the water-soluble pens have always lasted longer than the heat-erase pens – my top two choices for marking tools are the Sewline Styla Water Erasable Roller Pen and the Clover Thick Point Water Soluble Marker. Both markers have a light blue color that marks well on most fabrics. For blacks and dark fabrics, I accompany these water soluble pens with the Dritz white Water Soluble Marking Pencil. 

Check back for a deep dive into the pros and cons of all of my marking tools. 

Heat-Erasing Frixion Pens

Heat-sensitive fabric markers, such as Frixion pens, work very differently from water-soluble markers. Instead of dissolving in water, they rely on a chemical reaction within the ink that changes the color of the dye (making it invisible) when exposed to heat. Frixion pens are a favorite for their crisp lines and satisfying “erasing” with the swipe of a hot iron - but understanding the science can help you decide which projects to use these pens on and which ones to avoid!

Marker Ingredients

• Dye - a thermochromatic ink that can switch between colored and colorless states

• Acidic compound - this helps the dye change its molecular structure 

• Temperature-sensitive solvent - controls how the change happens

Now down to the Science

We often refer to all heat-erasing pens as Frixion Pens. This is due to the fact that Pilot Pen, the manufacturer of Frixion pens, was the first to develop this thermochromatic ink system. When you draw with a Frixion pen, the ink appears on the surface of the fabric like normal, but when you apply heat (like from an iron) the temperature causes the dye molecules to shift to their colorless state - making the marks appear to “disappear”.

The ink remains in the fabric, but the dye is now in its colorless form. In most cases, heat-erasing fabric pens are not water-soluble so it will not rinse out of the fibers like the water-soluble fabric markers will. Since the ink remains in the fabric, if the temperature drops (especially if exposed to the cold - typically below 14°F/-10°C) the ink can reappear. Don’t worry, the swipe of a hot iron will once again change the color state of the dye making it invisible all over again.

So What Does This Mean?

Heat-erase pens offer a great option for a clear line and many color options for marking, but just beware that the ink does remain in the fabric which means there is a chance it will reappear later. I have quilted several quilts using Frixion pens and have never had the marks come back - but my quilts are all kept at room temperature and never exposed to the cold. I do know of several quilters who have had marks returned after using the heat-erase pens so these marking tools are best kept for seam allowances or the back side of projects. If you do prefer the black or colored Frixion pens, you can always just iron away any marks that may reappear. 

Things to Note with Heat-Erase Pens

• The composition of the ink for heat-erase pens is very different from typical pens, including water-soluble pens, therefore expect for the ink to run out more quickly. More of the ink needs to be applied to the surface for the chemical reaction to take place to change the color of the dye, therefore the ink refill will be depleted more quickly. Just be sure to have extras on hand if you plan to mark a big project.

• With the heat on black fabrics, I have heard of quilters having the Frixion lines turn white instead of invisible. Be aware that ghosting of the lines or a slightly yellow line might remain after heat-erasing.

• As with all marking tools, be sure to test your fabrics before marking.

When it comes to marking your quilts, understanding how your tools work helps you make confident, informed choices. Water-soluble markers are great for projects where you want to rinse everything clean, while heat-erase pens give you a crisp line that disappears like magic – just know it’s still there, hiding in the fabric fibers.

Every quilt, fabric, and project is different, so the best thing you can do is test, test, test! Try your favorite pens on a fabric scrap before diving into your next masterpiece. And don’t forget: fabric marking tools are here to help you – not stress you out.

Happy marking and quilting!