Questions about foundation parging

[sawthroat]

I've got a foundation that the old coat is cracked and flaking in spots, probably needs some fresh parging. I've been knocking off the loose stuff and cleaning it back to a solid base. The plan is to pressure wash, let it dry good, then go in with a new coat.
Couple things I'm not clear on. Do you guys always use a bonding agent when re parging, or is a clean surface usually enough? And when it comes to material, is it worth buying the bagged parging mixes, or do you prefer mixing up a simple sand/cement blend?

I'd like this coat to last longer than the last one, so I'm open to hearing what's worked for you all

 

[Revmatch22]

Don't skip the bonding agent. A clean surface alone won't cut it. Spend the extra $20 for the right mix. It's a small price to pay for a job that lasts over 15 years, instead of just 5.