Too much research has left me VERY confused...

[Nelle]

Hey I taught Gigi all she knows about nappies! (PMSL, hi Gigi! ) I work the shift before her, I bet she'll be in around midnight?

Heidi, had you used panadol around the time of the stains? That's notorious for leaving a purpley-grey stain on nappies, so that would definitely be my first guess.
After that I'd guess mould, but it's unlikely...unless the nappies had been in there a good few days, or the nappy bucket got humid in the sun.

Sure you can soak if you like, though I've never gotten stains and I drypail (it might be worth giving drypailing another shot, if you realise panadol was the problem). I also wash my nappies in mostly just cold water (using soap nuts, a mild natural detergent, and a few drops of eucalyptus oil for a nice smell) and that works great too - we don't give our washing machines enough credit these days I reckon, they're much better than they used to be!

Vinegar is reputed to weaken elastic and PUL over time. So while it's great for a strip wash (a wash to strip chemical/oily build-up from nappies), it's not recommended to use it all the time.
I think bi-carb is the same.
Tea-tree oil, no probs, it's an antiseptic, so great, I doubt you're using that in a large enough quantity to cause any build-up!

Like I said, I dry pail, but if I was going to soak, it'd be in water. That should be all you need.

I think that's all I was going to say... Try dry-pailing again at a time when your bub hasn't had panadol and see if that was the culprit! If it wasn't panadol, pop in again and we'll go back to the drawing board, haha!

ETA: I KNEW I'd forgotten something! If you've still got stains, get those nappies out in the sun - UV light bleaches stains right away and kills germs! Hurrah for the sun!