Copper Sulphate

When I started my apprenticeship in 1995 as a die sinker in the cutlery industry I observed my foreman, who was an old Sheffield die sinker mark all of his dies with copper sulphate. I asked him why he used this and not marking blue and this was his description. When you mark out a die with a template the scribed line on normal marking blue can often flake or come away from the surface. This can be due to contact with the hand or the template its self. Copper sulphate provides better adhesion to the surface of the die and has less chance of coming away . This is also a better remedy for machining to a scribed line as the swarf stands less chance of rubbing away the copper sulphate as it does with marking blue. I have used copper sulphate for marking out since then although I think modern marking fluid is just as good, depends on what type you use. I thought I would just share this with you as you may want to try it some day. You can purchase copper sulphate from e-bay. Just mix it with water in a jar so it is a dark blue colour then it will keep for a very long time.

Nathan,

Excellent advice, and well-worth sharing.

MichaelG.

Hi

There is a proviso with using copper sulphate in that the surface to be coated must be totally clean and free of oil and grease etc. This is because there is a chemical reaction where the copper replaces the the top layer of iron of the item being treated. In fact where the copper sulphate solution is applied the item is effectively copper plated, albeit a very thin layer, and this is securely bonded to the underlying metal. The other point is that the item should be cleaned thoroughly afterwards as there will be traces of ferrous sulphate which could be corrosive.

While not having used this method myself I have, when I was a kid, dipped ferrous objects into copper sulphate solution to copper plate them.

Cheers

Martin

Nathan, used Copper Sulphate many times in the past and for ferrous metals it can't be beaten in my opinion.

Tony

Used this in my first metalwork lesson at school (about 55 years ago!!!) when marking out a square of 1/4" thick MS from which to cut (and file ***!) the handle for a poker. The poker bit was 1/4" square with a decorative twist in the middle and was eventually brazed into the handle. I was quite proud of it at the time and it did get used for a few years. I guess it must have sparked something off.

Norman.

I have used this (but with a drop or two of sulphuric acid as per Sparings book). It works, but to be honest I've resorted to using a big fat permenant marker. It's cleaner and does not flake off. I also use both blue and black so that pairs of components can be colour coded.

> blue and black so that pairs of components can be colour coded.

I use blue and black, but never thought of that, what agood idea! Thanks Steve.

Neil