I used a stainless steel butter knife to stir a sodium hydroxide solution & it ate the coating right off the knife.

Anyone have an idea of what might have caused this?
What is normally used to coat stainless steel & is it possible this could end up in my end product?

How hot and how concentrated was the solution? Are you sure the knife is stainless ? It should hold up well. How come you ended up stirring in this way? Usually mixing by agitation with a tightly screwed lid is the safe route for liquid extractions.

NaOH dissolving should be stired with plastic spoon only, no any metal should touch it.

Any base or acid goes into the water, not the other way around, else it may jump into your eyes.

All neutralization should be done with cold, room temp at least, since they release heat or can jump into your face.

They sell 1 ltr. mason jars for like 10$ for a pack of like 20 or more I cant remember the amount in the pack but they are cheap and one pack of those things will last almost forever

edit: I average 250g of extraction material reduced to 650ml, rest is non polar solvent to make the liter, works great

Plus, you can shake em instead of stirring.

Naoh was poured into cold water in a pyrex measuring cup & the stuff that stuck to the bottom was stirred with a stainless steel knife.
I have mason jars but i dont like the thin glass for mixing lye solutions.

The knife looked like it had spots eaten up on it but i guess it was nothing. After it was washed it looked perfectly normal & the coating wasnt even damaged. Im a little confused as to why it looked damaged at the time. May have been small lye crystals stuck to the knife.

I would like to strongly discourage people from dissolving larger amounts of lye in glass containers. It causes localized heating and may cause the glass to shatter, with possibly catastrophic results from spilling the strong lye solution.

As stated above, good quality stainless steel should not be substantially attacked by lye and is thus a much better material to work with. I suggest using a stainless steel cooking pan.

To prevent the yet undissolved lye from forming a harder to dissolve crust on the bottom, stir the water well right before adding the lye and keep stirring after adding the lye, keeping the undissolved pellets in suspension. This should also help to prevent the lye from staining the metal.

When preparing concentrated lye solutions, be prepared for a caustic mist of lye solution. The heating up and saturating with ionic lye forces small bubbles of dissolved air out of the water. These carry a mist of tiny droplets from the lye solution when they pop at the surface. Work in a very well ventilated area and use safety glasses that fully cover the area of the eyes.

ive had a silverware fork permanently go all metalic purple dye color (as if anodized) on all the fingers, but i only ever used that to keep material off the bottom of my pot, not ever basic solution. the only thing id trust in a basic solution is glass. (HDPE2 too, but to a lesser degree). at any rate, im pretty positive that naptha wouldnt pick up any of the metals that may corrode into the solution (correct me if im wrong).

Stainless steel is steel that has been alloyed with chromium. The chromium disperses itself throughout the metal, so if the surface coating is damaged, the chromium in the metal will migrate to "heal" the damage & repair the surface, protecting the steel from further corrosion.

While the second part may be true, a simple experiment proves the first statement to be false.

I work in a kitchen where we use stainless pans and there is one fella who uses the degreaser to clean troublesome pans by soaking them overnight. The NaOH etches the pan when left to "soak" for only 8 hours.

I kinda doubt that stainless steel is affected from a stirring or two, but I never stirred my lye with anything made of it. Silver plating seems like a reasonable guess. Some kind of plating. Take it to a pawn shop they'll tell ya.