Chemical blackening

[nberrington]

Greetings all. I recently ran a few experiments with a locally available chemical blackeing for metal. It is a bluish liquid, which patinas metals rather well. Brass takes on a charcoal/ bluish colour - similair to gunmetal. I have not tried large items with longer exposure, but is seems rather good for brake rods and the like.
My question is - does anyone have experience with similair chemicals? Specifically if I was to dunk a chassis in the stuff, would it affect moving parts such as hornblocks and compensation beams? It would seem infinately better than paint for the working bits.

[modelmaker87]

Greetings all. I recently ran a few experiments with a locally available chemical blackeing for metal. It is a bluish liquid, which patinas metals rather well. Brass takes on a charcoal/ bluish colour - similair to gunmetal. I have not tried large items with longer exposure, but is seems rather good for brake rods and the like.
My question is - does anyone have experience with similair chemicals? Specifically if I was to dunk a chassis in the stuff, would it affect moving parts such as hornblocks and compensation beams? It would seem infinately better than paint for the working bits.

Yes, I have experience with chemically blackening various alloys. I have used both Hoppes gun blue, the very stuff gun smiths use to make the guns the black colour they are. My preference these days is to use copper sulphate solution, inexpensive too. Any pharmacy will sell you copper sulphate crystals. Drop them into warm water and stir, just as you would sugar in a cup of tea until all the crystals have dissolved. Then dip whatever item you want blackened into the solution. The strength of the solution will determine how fast the blackening process takes place. I make a strong solution for speed. Brass wire, connecting rods, wheel rims etc will go black within 10 seconds. The weaker the solution the longer it will take, however the advantage of a longer blackening period is that you can take the item out of the solution before its completely black, brownish instead or even a light straw colour, if you will.

Cleaning is paramount with copper sulphate solution otherwise the active ingredient keeps on oxidising the surface. I'd say each component dipped should be surgically clean...!!

HTH

Tony Sissons

[LesGros]

I like the sound of a cheap alternative. A few wee questions: How much Copper sulphate do you use in a mix, and what quantity would/do you buy from the pharmacy. Also what do you use to clean it off?

TVM

[Tim V]

Or you could use a permanent marker felt tip pen.......

[LesGros]

Thanks for thought Tim, but I what I had in mind is blacking lever frame cover plates, my experience of markers (when setting up chisels for sharpening) is that results are poor on anything other than small components, the finish being too streaky.