Advice needed to caulk a joint

Plumbing pros,

I am trying to caulk this quarter bend fitting onto a 3" hub pipe. Is there a special tool or technique needed to caulk the lead under the inside bend of the fitting? My shortest caulking tool is too big.

Any input would be greatly appreciated.


Thanks in advance

piping should be supported so the their is free annular space around the fitting,
if you do not have a caulking iron use a chisel

or, a piece of 1/4'' x 3/4'' steel, and a grinder..make a tool

Thank you Frodo. I looked for anything small enough to get into the 1" radius around the hub so I could tap the lead. I ended up using a 1/4" combination wrench. I was able to tap the lead inside, middle, and outside and got a water tight joint.

Over the past seven years I have been experimenting with leaded joints. I had 3" cast iron hubs left over from a plumbing renovation I did back in 2008. I removed all the service weight cast iron pipes and fittings because of damage and rust. I installed ABS in place of the cast iron.

I bought oakum, lead, caulking iron, packing iron, and 3" cast iron pipe. I packed the oakum into the hub and poured melted lead. I used a hot plate and a Bernzomatic Mapp Gas torch to melt the lead. I then used the caulking iron to attempt to get a water tight and gas tight leaded joint. I then placed a Pasco test plug in one end of the pipe and a pressure gauge air leak test assembly in the other end. I pressurized the pipe to 8 psi using nitrogen gas. If there was any leak, I tapped the lead over and over until I got a gas tight joint.

I also learned how to pour a horizontal joint using a runner.

Here is a picture of a hub fitting and cast iron pipe under test after I poured lead and caulked the joint.

your gauge looks a little high.

5 psi [34.5] kpa for 15 minutes