I had an issue with a pullet that might have warranted a bath... but, I used scissors and baby oil instead. I'll share the little story with you:
I was going out to shoo the stragglers into the run so I could shut it up for the night. One of the Colombian Wyandottes was running around. She...
Bathing chickens removes their natural oils. PD gave you the most appropriate advice. Orpingtons have fluffy butts. Trim a bit and she should be able to keep herself clean with normal dust bathing.