Will the lime sulphur work on steel? I have a knife project to
do, .... If lime sulphur won't work, what are my other choices for a
knife blade?
Karen, Lime sulphur or liver of sulphur works by creating sulphides
of copper and silver on the jewelery metals they’re used on. These
are generally blue/black in color, with thin layers of the sulphide
giving more transparent colors, like blue, etc.
Steel might react with the stuff somehow, but I can’t imagine just
how, unless it’s acid based. Most likely you won’t get a decent
color from it.
Instead, try a sporting goods store that carries stuff like gun
cleaning products, especially the Birchwood Casey line of products.
They make both gun blue liquid, and Gun Brown liquid, both of which
are just brushed on the very clean iron or steel to produce the
described colors.
You can also heat color the metal, though if your knife is tempered
steel, then blueing it will make it softer, since the temps needed
for a blue oxide are somewhat softer than usually desired. Brown is
a good spring steel hardness, and might be OK. Don’t have the exact
temps handy, but I’m sure someone would have it around. If you’re
"supplier" can’t get to it in a while, i’d bet he/she is heat coloring
the steel, since the chemical way is simply really easy and quick,
and you can do it yourself if you find and buy the liquid. Just be
sure the steel is very clean first (also with heat coloring, since
dirt or oils will leave stains/marks on the colored surface too. To
heat color, you could, if you’re not picky, just carefully do it over
a flame, or even on the kitchen stove, gently heating till the color
develops, and quenching when it gets to the right color. More precise
would be to use a kiln, for which you’d then need to know the right
temps to set it at. The kiln would tend to give you more even color
over the whole piece, while doing it the manual way with a torch or
over the stove would be more prone to give you some variations in
color from one part to the next, since it might be harder to get
exactly the same temp over the whole piece. But then, that might
well be quite attractive too, looking more like the presumably
handmade item it is.
Peter