What colourfastness actually means for embroidery floss

Colourfastness is one of those words that appears on every thread listing and rarely gets explained. It means the dye stays where it was put — through washing, through daylight, and through contact with damp fabric.

Why red is the usual culprit

Deep reds and some strong blues need dye loads high enough that not all of it bonds to the fibre. The excess sits on the surface. In dry use it never matters. Add water and it lifts, and it will happily migrate into the white linen next to it.

This isn’t a sign of cheap thread specifically — it happens with expensive hand-dyed floss too, sometimes more, because small-batch dyeing gives less control over rinse-out.

Testing before you commit

Cut ten centimetres of the colour you’re worried about. Put it in a glass of warm water with a drop of the detergent you’d actually use. Leave it twenty minutes.

If the water tints, that colour will bleed on your finished piece. You can either rinse the whole skein repeatedly until the water runs clear before stitching, or plan not to wash the finished work at all.

Washing a finished piece

Cool water, never hot. A neutral detergent, no bleach and no optical brighteners. Move it gently rather than rubbing. Rinse until the water is completely clear, then roll it in a towel to take the bulk of the water out.

Dry flat, face up, away from direct sun. Press from the back through a cloth while still slightly damp, and never put an iron directly on satin stitch — it flattens the sheen permanently.

And light

Daylight fades thread. Nothing prevents this, and no thread is exempt. A finished piece hung opposite a south-facing window will lose its brightest colours over a few years. Hang work on a wall that doesn’t get direct sun and it will keep for decades.