Doupioni. Dupioni, Douppioni, Douppione, Doppione. All the variations of spelling mean the same thing–Double. Doupioni Silk threads are spun from silk cocoons that were spun too close together. This filament is usually from cultivated silk due to overcrowding. In the wild, silk worms have lots of room to spread out, so double cocoons rarely happen. When the filaments are un-spun from the cocoons, there are thicker slubs where the cocoons crossed over. That’s the technical portion of the filaments. On to the technical portion of the fabric.
The slubs are structurally weaker than the other silk filaments. For this reason, the warp threads are never doupioni–they can’t take the stress of being strung on a loom. So the warp threads are pure silk filament. The weft threads are of the doupioni threads. And as stated, they are considerably weaker. Which means this fabric, while really easy to work with, is prone to seam slippage, pilling, and abrasion.
And yet, probably because of how easily available it is, Doupioni remains the preferred silk of costumers and home couturiers. It is structurally inferior in virtually every way. It is texturally interesting, with the slubbiness adding visual contrast to the smoothness of silk. Additionally, the texture makes it very easy to work with. It dyes well and is frequently found as a shot silk. All of this makes it very appealing. Which is fantastic for cosplay and modern couture. Not so much for historical costuming.
But, silk is silk, even structurally inferior silk that is readily available. And if you have to choose between sweltering in a polyester Elizabethan or being stylish in silk, go for the silk. Even the Doupioni. And when you can afford it, go for the Damask. Or the Taffeta. Or even the Habotai. Or use the Doupioni. It is a great fabric, widely available, in a gorgeous variety of colors.