single ply or multiple ply?

Is single ply okay for knitting with when you are making a sweater or are you better off using a two, three, or four ply yarn.

I don’t see why you can’t, but it would take forever!

I’m working with a Jill Eaton single ply (4.5sts/inch) right now. It’s wonderfully soft but since it’s loosely twisted it tends to untwist. It’s also a bear to knit with since it splits into tiny fibers. Other than that, you can certainly knit with it for a sweater but you’ll have to be patient.
What yarn are you considering?

@Evie single ply can be thick or thin. It depends on how it’s spun. Here in the US we don’t base yarn size on ply since it can be varied.

@shadowfox118 Single ply can untwist as salmonmac said or it can pill. The number of plies doesn’t matter too much it has more do with how it’s spun and plied. Just look at the yarn and/or read comments on it in Ravelry and see what other said.

I’ve seen a lot of projects but no one has talked about how it wears, I ordered a sweaters worth of it and another yarn and I think I may just play with the single ply as something else like a hitchhiker.