used watering can for weedkiller, what to wash it out with?

[Penellype]

Penellype, I have been speaking to my ex-partner who used to do the blueing process, along with your chemicals there was an addition of caustic soda a mix called 'traditional caustic black'.

This mix was placed in a special stainless steel bath and heated to 135' to 155' centigrade, the gun parts were the in for around 30 minutes.

Yes, caustic soda is sodium hydroxide. Very strongly alkaline, very nasty. My chemistry is very fuzzy nowadays as I haven't used it for years, but iron has 2 possible oxidation states and the bluing process is designed to form a thin layer of the less destructive oxide so that the metal does not react with moisture in the air and form the more destructive rust. I can't remember how it works but it clearly does or they wouldn't do it.

[TattyJJ]

All weedkillers available to public are pretty mild these days and should easily go with a few good rinses, maybe an overnight soak. See if you can get your head in there and give it a scrub if really worried.
Why would you want to introduce any other form of chemical that could harm the plants? Pretty sure bleach residue is going to be just as bad a weedkiller residue....

[snakeshack]

Bin the can ,buy another from the pound shop.You will probably spend more on chemicals getting it clean than the cost of the can,you will also have produced chemical waste you didn't need and have to dispose of. Environmentaly speaking the best solution is to give it away to someone who needs a separate watering can for weedkiller

[bearded bloke]

See if you can get your head in there and give it a scrub if really worried.

Or possibly your .... hand .... might be better suited to the task

[Potstubsdustbins]

^^^^^^^Depends on your hairstyle I suppose.....................

[Bigmallly]

[nick the grief]

go to your pound shop and buy a new one and keep that one for weed killers .... not worth the hassle