Hi Steve/Minty,
Dralon is an acrylic fibre with a melting point of roughly 250C , but being a thermoplastic it wil start to soften at a much lower temp.
When it has softened it's possible to reshape the fibres which is what these steamers do , causing the dralon to reflect light in a different way.
Once this has happened , there is nothing you can do.
Cheers,
Doug