Black iron pipe finishes a guide to our finishes and how we create them
Our first finish which is the easiest one is natural this surface finish is our basic no extra finish.
This is not really a finish of sorts the “black” that most people will have heard when they see items such as black pipe shelving or furniture that inspired the search of the internet for “black iron pipes” or “black iron pipe fittings” – more than likely a search term you yourself the reader of this page entered into your search bar, not long ago!
The black is, black oxide formed when the metal cooled after processing into the pipe lengths that we cut and thread. This layer of oxide does give a little corrosion protection, but it is far from being a protective coating, basically kept inside and away from moisture it will remain black but add moisture and air and a different kind of oxide will form, Rust
Now to add more confusion we get asked quite often “what colour is natural?” we can only say it depends on the surface of the material I have to illustrate the image below is of two pieces of natural black pipe next to each other both are natural and untouched finish wise
On researching for this guide, we came across many descriptions of colour but the best answer we have seen is ”this is of no set colour and can be silver ranging to a deep black and even a brownish colour”
I would agree with this statement as this pipe could potentially be shot blasted (silver) a bluish grey to black (mill finish) or even slightly rusty (brown)
Having said this here at threaded pipe we tend to use the materials best suited to what we are going to be doing with them for instance if we are painting them it doesn’t really matter if the natural surface is not aesthetically pleasing as long as we treat the metal correctly by cleaning sanding and applying a decent rust inhibiting primer before painting there will never be a problem
onto the malleable fittings so the colour in this case is more uniform but it is not black as implied in the common name “black malleable pipe fittings” my best descriptive name for this colour would be a matt dark grey.
Malleable fittings are made by casting “white iron” which after casting is annealed (heat treated) to make it more malleable or less brittle than normal items made from cast iron.
To sum up the pipe and fittings very rarely match in colour both fittings and pipe in their natural state will rust in the presence of oxygen and water (including air moisture) that will enable the oxidisation process of iron and its alloys (steel)