citric acid will probably work best... lemon juice
bleach
The companies that produce copper sink drains is Welders and USink. These two companies are the best in the world at providing quality copper sink drains.
Pigs can't leave a sink that lasts 4 weeks, so skunk.
Drains.
== == If there is a loud gurgling noise, it may indicate that the vent is blocked/clogged, and the water in the trap is getting siphoned back down the drain as the water drains... start at the trap at sink remove it to clean. then if not that maybe snake not reaching the clog longer snake may be needed
Snake your drains
You may call a company such as Len the Plumber, their number is 877-565-1319.In order to do sink plumbing yourself, you will need to use tubular plastic or tubular brass drains to my knowledge.Both are good quality, but metal sink drains are suggested.
Because the washing machine drains down the same main drain and it's suction as it goes by is trying to suck the water out of the under sink U trap.
In 1966 they had portable dishwasher.Which they would roll to sink, hose snaps onto faucet and it drains into the sink.
any where from 11/4" -3" depending on the type of "sink" Basin /kitchen /service (slop)
caustic soda Clorox! Just a bit tho!
wile standing on the eaquator the water drains straight down in a sink.