Volume markings on large pots and mixing bowls make life so much easier. They cut out the step of measuring and save you the trouble of washing measuring cups. However, there aren't many containers out there that actually have volume markers in them.
Good news is that you can make the markings yourself at home without buying any expensive etching tools. Redditor itsgus came up with a brilliant way of etching stainless steel using salt and vinegar, which can be combined to make an electro-etchant. His "etching tool" was simply a cotton swab connected to the negative end of a 9V battery.
It works because the salt dissolving in the vinegar creates an electrolytic acid containing negatively charged ions. The positive end of the battery is attached to the container, and when the etching tool is hooked up the the negative end, it removes a little bit of metal wherever the current touches. As itsgus points out, hooking them up the opposite way would actually make it try and add metal to the container instead.
In order to get clean lines, you'll need to use a stencil to keep the current from coming in contact with the metal outside of where you want it etched. You can use black electrical tape if you just want straight lines. The end result looks pretty great considering the whole process only takes a few seconds once it's hooked up.
It's worth noting that if your container is coated on the inside, etching may ruin it, so stick with plain stainless steel. If your container doesn't have straight sides like this one, the measurements won't be equally spaced. Regardless of the shape, make sure you measure with actual liquids before adding any permanent markings.
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