Originally Posted by douglmi
Someone suggested that I get some sort of bladder and put it on the end of a garden hose
That's what I use.
The high pressure hose water fills the pipe up to the blockage and pushes it out. If you don't have the bladder device just put the hose in the pipe a half foot or so and pack the space around the hose with rags. Jam them in there with a stick.
For difficult jams the hose will try to come out of the pipe, so push down hard. Have a second person turn on the water.
The last time I did this for a disposal blockage, it held and the hose water came out of the vent pipe on the roof along with chopped vegetables and whatnot, so I plugged the vent pipe roof opening with a small inflatable barrel-shaped device which plumbing supply houses will have.
This little barrel is used to plug concrete shower stall base drains to check for leaks and it comes in several different sizes.
That worked in an instant. Most blockages can only withstand a few PSI but a 10' water column (about 4 PSI) in the vent pipe wasn't enough.
With the vent plugged the pressure went up to 50 PSI or so.