A shop rag vs. actual degreaser on a 20 year old chain, and I feel dumb

Last week a guy rolled a beat up Trek into the shop with a chain so caked in grease it looked like a gummy worm, and my first move was to grab a rag and start scrubbing like an idiot. After about 15 minutes of going nowhere, our lead mechanic handed me a can of real degreaser and a parts brush and the grime came off in two minutes flat. I had been treating that rag like it was gonna do the job, but all it did was smear the mess around and leave my hands black. The chain went from crunchy to smooth just from letting the solvent sit for a minute and brushing it out. Any of you got a go-to cleaner that beats the stuff we keep in the back, cause I'm tired of guessing?