UV Color-Changing Embroidery Thread: Tips for Use!

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When we visited Dinosaur World, my daughters got solar-reactive souvenir shirts that were white but changed colors in the sun. They were a hit, and I wanted to find a way to create projects with similar properties.

Now, I’d heard of SolarActive’s color-change threads years ago, but after spending years scouring local sewing shops and sewing expos for them, I gave up and filed the idea of creating color-changing projects as a lost cause.

Imagine my excitement when I discovered that Amazon now has UV color-changing embroidery thread! I was so thrilled that I bought an 8-pack and have been trying to incorporate these specialty threads into as many embroidery projects for my daughters as I can. 

Read on to learn more about this embroidery thread type and tips for use!

uv-color changing embroidery thread

Color-Changing Thread Responds to UV Light Sources

UV color-changing thread starts as one color and changes to a different color when exposed to the sun or another source of UV light. Some will change from white or a pastel color to a more vibrant color, while others start as one color and change to a completely new color. 

Color-changing threads are also known as photosensitive threads, light-sensitive threads, or Solar Reactive Threads. 

I haven’t been able to get my hands on any old-faithful brands, but I recently acquired New Brothread color-changing machine embroidery threads, which have been great so far!

How Photosensitive Thread Works

thread before it goes in the sun

Since UV-sensitive thread responds to UV, the speed of transformation and intensity of change will theoretically vary depending on the level of UV exposure.  Thus, it’s not too far of a stretch to expect small variations in behavior between times of day, seasons, altitudes, and even geographical locations. 

I can’t attest to climate differences as I live in sunny Texas, but the color-changing effect during a mid-day 80-degree Fall day is beautifully intense for 7 of the 8 threads!

Also, when no longer exposed to UV, threads return to their normal color quickly.

All the threads had lost their new colors within 2-3 minutes of returning inside. In fact, even while outside, if I covered a portion of the spool with a finger and then removed it, I’d notice a color difference immediately. 

What Colors The Threads Change

color changing thread inside and outside colors

I took pictures and documented the before and after thread colors of the Brothread spools before I started using them on my machine.

Here’s what I discovered, listed by thread number. 

  • UV01: White to bright pink
  • UV03: White to orange
  • UV05: White to yellow
  • UV07: White to pastel blueish
  • UV09: White to pinkish/purple
  • UV14: Blue to purple
  • UV15: Neonish green to pastel green (not super impressive!) 
  • UV16: Yellow to pastel orange

Tips for Working with Color-Changing Thread

a shirt with color changing thread on it

Now, here are some things to consider when machine embroidering with UV-sensitive threads. (You can also use this embroidery thread on a sewing machine!)

1. Use 40wt Thread Normally

If you have 40-weight UV-sensitive thread (like SolarActive’s), it can be substituted easily in any embroidery design that you’d use regular polyester or rayon 40-weight embroidery machine thread. 

Just remember, pick your colors so the design looks decent before changing colors and after changing colors. (To remember which color did what in the sun, I wrote on the UV color on the base of the thread spool.)

2. Use 30wt Thread As You Would Any 30wt Thread

My New Brothread UV-color changing thread is 30wt thread, which means it is thicker than normal 40wt embroidery thread. 

Since embroidery designs are almost always digitized for 40wt thread, you may need to edit your design for the best results. 30wt thread is great for applique borders, though, as it provides full coverage so you can’t see fabric borders. 

Also, don’t use a needle with a small eye, as 30wt thread will have more difficulty passing through without shredding. 

3. Pair with Regular Embroidery Thread, Too

Inside a building, color-changing threads are all white or boring pastels.

Thus, feel free to pair it with regular embroidery threads to give designs more texture and viewability when indoors. For instance, add black outlines to large areas where color-changing threads are used, and don’t be afraid to add other colors. 

4. Adjust Tension, If Needed

If you see your bobbin thread showing on the top of the embroidery, you may need to adjust the tension to prevent the bobbin thread from disrupting the color-changing effect on the top of the embroidery blank. 

Sometimes when I switch to 30wt thread, my machine requires a little hand-holding to get good stitching.

As for the bobbin, feel free to continue using your normal machine embroidery bobbin thread. No need to wind bobbins with the color-changing embroidery thread unless your project will be viewed from both sides. 

5. No Special Wash Instructions Needed, and Iron Normally

I washed twice with the Brothread UV threads and noticed no difference in the color-shifting properties afterward.

Granted, after 50+ washes, I cannot make any promises, as I have better things to do than keep washing the same shirt repeatedly! (Also, I didn’t test with bleach. I really wouldn’t recommend bleach.)

I also pressed the embroidery design (from the back) using a medium-heat iron, which did not affect the properties of the thread either. 

Lastly, I tried 10 consecutive in-and-out of the sun movements, and the threads still changed as vibrantly as ever over that small course of time. While SolarActive threads, which have been discontinued, promise 2,000+ launderings, I don’t have that quantitative data about the Brothread threads. 

All this to say, I imagine there’s significant longevity with solar-active threads. However, since the sun destroys everything in the long term, I wouldn’t use them on an embroidery blank that will live outside full-time in prolonged UV exposure. 

Project Ideas

shirt with embroidered rose in uv thread

Besides shirts, other fun ideas for color-changing thread include swim towels or beach towels, sun umbrellas, beach tote bags, garden flags or banners, hats, and even dog collars. 

The sky’s the limit (pun kind of intended) when it comes to projects–just choose anything that goes from outside to inside.


And that’s a quick summary of my newest embroidery supply find! Any other tips for using color-changing embroidery thread or other fun project ideas? As a mom of two young easily-fascinated daughters, I’m all ears. 

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