When I first started this hobby I read about using flour dough/paste to seal a pot, but I thought the experienced distillers were just pulling my leg. After all, how could flour + water make a seal. Well when I upgraded from a aluminum pressure cooker to a stainless steel stockpot I thought I would give it a try. To my amazement it works! and it works well!
Here's my technique in pictures. If there any critiques of how I could do it better please let me know.
Here's my stainless steel stock pot -
As you can see there really isn't much of lip to the pot. I found a stainless steel mixing bowl the exact diameter of the pot. It has a nice lip on it.
I use this handy little Black&Decker mixer to make the dough. About 1/2 cup flour to 1/4 water. I adjust the mixture with a little water or flour to make a dough that is sticky but not to sticky otherwise it just ends up in my hands.
I take the dough and break off little chunks and roll it between my fingers to make it about a diameter of a pencil and apply it to the bowl.
I do a bit at a time, overlapping the ends. I'll wet the dough a bit to make a good seal. Also, not seen in the pic is the dough wraps around the edge of the bowl.
Then I put the bowl on the pot and clamp it down with some black springy paper clips. I first clip 4 clips at 12, 3, 6 and 9 o'clock to make sure the bowl is exactly aligned.
Then I finish up by putting the rest of the clips around the bowl.
This method works really well. Takes very little time. I can fill up my pot with wash and turn on the stove. I have plenty of time to apply the flour dough, seal the bowl and assemble the rest of the still - which I can do in about 8-10 minutes.
I've heard of the term flour paste as well. I'm assuming its flour and water but probably a thinner mixture for sealing up different applications like maybe pipe threads.