Introduction To Metals
Founders will use a common purpose or an all-rounder alloy unless otherwise asked of by the customer. Such a default choice is the best option most of the time, though it can hide the truth of the immense diversity of available metals and their metal alloys for use in casting metal objects.
The default foundry metal is predictable and suitable for most founding, from their fine finish, to easy pouring capabilities. However, inevitably it limits the creative possibilities and the option of exploring a different set of patinas. So that is why this site will have pages a’plenty to showcase all the alternative or somewhat daring and unusual variations. This page will also offer a definition for two terms of alloys: Wrought and Casting.
- A casting alloy is designed to be used with moulds by first melting the alloy then pouring the hot substance into the mould. Such alloys are stored or supplied in bars or ‘ingots’.
- A wrought alloy is designed to be used by hands and tools. Such alloys are stored or supplied in plates, angles, channels, and so on.
In a few cases here and there, the alloy’s composition is identical in both casting and wrought form. Generally, there is some variation in the chemical arrangements to allow for the unique requirements of either term. And there even are other non-wrought-versus-casting reasons for such difference.
To define what an alloy is, we have to determine its components or are even called.
- An alloy is formed from combining at least two or perhaps more ingredients, united for creating a new, and most often distinctive to both or all component parts, metallic material.
- An element is the lowest order chemical substance, one that could not itself be broken down into other component parts.
- A pure metal is a metal that has not been alloyed with another metal or other chemical substance.
- A metal is any substance that is naturally hard, shiny, ductile, malleable, fusible, and is a good conductor of heat and electricity.
In theory, the alloy-making process for most alloys can be reversed into their component elements, e.g., aluminium and lead, which form a molten mixture when – well, molten –, but follow oil and water’s lead and separate out with cooling.
In practice, though, dividing the elements or otherwise distilling an alloy into its component parts is impossible, partly due to their complex and varied combinations.
- Like copper and nickel alloys, some become entirely soluble with each other in any proportion and form a homogeneous compound.
- Like zinc with copper or zinc alloys (30/70 brass), some create a solid solution.
- Like 60/40 brass and iron + carbon, other elements may form intermetallic compounds – unless, like some aluminium and silicon alloys, they are only partially soluble, leading to them being labelled as a eutectic system.
Of course, the average artist has no real need to understand metallurgy in detail to start appreciating the visual niceties caused by an alloy or metal. However, it is genuinely worth acquiring awareness and appreciation of the rich and sometimes staggering complexity and the various factors at play of the materials one has to work with.