We are proud to introduce the all-new photochromic thread from Langus Goods. This thread changes color when exposed to sunlight or UV light and changes back to its original color when sunlight is blocked. If you are looking to add magic to your creation, this thread will produce results. This thread can be used for sewing, embroidery, weaving, string art, cross-stitch, and so much more. Using a single strand will create a fine and extremely subtle effect. Plying, braiding, or cording the thread to make it thicker will create a bolder effect. When designing a project, think about the application, including the fourth dimension: time. How should the project look before and after the color change? White to Purple, White to Blue, White to Pink, and White to Yellow respond the fastest to UV/sunlight and have the most dramatic color change effects. Most consumer UV lights have the intensity and correct wavelengths (angstroms) to activate the thread's color change. White to Orange and White to Yellow require a stronger UV source and the necessary UV light wavelength. Low-end consumer UV lights do not have the required wavelength for activation. Direct sunlight will always create the most vibrant and dramatic color change effect! Colors Available: White to Blue White to Pink White to Yellow White to Purple Yellow to Red Length: 2,500 meters/2,700 yards Weight: 100 grams/3.5 ounces Thread Size: 150/2 D or 30 wt Material: Polyester Washing and care: * Iron on low, avoiding direct contact. Do not steam. * Avoid harsh detergents/chemicals * Machine wash with cold water * Air dry or tumble dry on low.