AJKOER - 31-7-2022 at 05:11
First, contrary to usual directions (see, for example, discussion here https://www.liquidplumr.com/diy-plumbing-tip/how-baking-soda... ), you cannot pour hot water into a drain that's plugged as it only dilutes the
possible reagents and makes the problem worse.
Start by removing excess water in the drain itself. I successfully rolled some paper towels together, forming a stick that is dipped up and down with
intermittent squeezing out in an external vessel as a path of gradually decreasing the content of water.
Next, add an excess of Baking Soda as a powder into the drain.
Finally, add vinegar into the drain and as the action commences have a suitable plug available to put over the drain and hold down.
IMPORTANT: Do expect a possible backsplash so wear appropriate clothing and eye protection.
Add more vinegar and listen for further bubbling action and reseal as before.
Repeat as needed.
MECHANICS
I suspect the vinegar helps with the process, but it is primarily a pressure tool per bicarbonate generated CO2 that makes it work!
My guess is Washing Soda (Na2CO3) would be a just as effective as Baking Soda (NaHCO3).
TheMrbunGee - 31-7-2022 at 05:52
Chemical plunger. I guess, when One has no other options. 
I'd stick to NaOH, because plunging would remove bare minimum of obstruction, leaving drain to be vulnerable to future blocking, while dissolving
obstruction leaves 100% free drain where there is less chance of stuff to get caught and make another block.
mayko - 31-7-2022 at 06:27
When I do this, I usually add a bit of water after the baking soda and leave it for a while, so that it can percolate into the clog. That way the
effervescence can break the mass up from within, rather than just from above.
clearly_not_atara - 31-7-2022 at 07:53
I've tried many variants of the "break up the clog" technique with baking soda and none of it ever seemed to work. Pressure, on the other hand, has
consistently worked. Maybe it depends on what's clogging your drain.
violet sin - 31-7-2022 at 09:06
Lye works nice. TSP will cut a grease clog down to size. Depends on what your fighting. Last clog here was, to the best of my observations, caused
by salt running low on our water softener. I found a hard waxy/chalk like white substance stuck in the drain snake tip. Think it's calcium/magnesium
soap scum. When the salt runs low the resin bead ion exchange unit let's Ca/Mg water through.
About 6 rounds of 1 Tbs. Lye, waiting, some patients and a cheap drain snake got it.
I have no idea how far you can get with baking soda and vinegar. In my situation, I'd doubt very far. Good luck
AJKOER - 31-7-2022 at 09:42
While not usually cited, Washing Soda here, especially if one decides to employ near boiling vinegar, may increase the suspected weak chemistry here
for added effectiveness. However, any spattering from the CO2 mix is now more likely problematic (more caustic and hot).
As such, I stand by my original recommendation, however, I am open to recommendations from any resident biochemists 
.
WARNING: Further reading my produce indigestion in sensitive people especially having recently eaten.
In this instance, the clog apparently arises from person(s) unwilling to completely scrap residual food from plates and pans. This results, apparently
(per smell), in a biomass of decaying foods/oil.
wg48temp9 - 31-7-2022 at 09:44
I had a blockage in the outside drain for my kitchen. I tried to unblock it with one of those coiled spring things but I could not get it through the
bends to the blockage. I also tried with a hose pipe but had the same problem.
So a made a wooden plug to fit and seal where the grid had been. The plug had a hose adapter attached. I turned on the water to the hose pipe and
held the plug in place. Initial the plug leaked but once I managed stop that, the pressure pushed the blocked away and presumably breaking it up the
process.