Editing Type metal (section)

== Contamination of type metals ==
=== Copper ===
[[Copper]] has been used for hardening type metal; this metal easily forms mixed crystals with tin when the alloy cools down. These crystals will grow just below the exit opening of the nozzle in Monotype machines, resulting in a total blockage after some time. These nozzles are very difficult to clean, because the hard crystals will resist drilling.

=== Zinc ===
[[Brass]] spaces contain [[zinc]], which is extremely counterproductive in type metal. Even a tiny amount —&nbsp;less than 1%&nbsp;— will form a dusty surface on the molten metal surface that is difficult to remove. Characters cast from contaminated type metal such as this are of inferior quality, the solution being to discard and replace with fresh alloy.

Brass and zinc should therefore be removed before remelting. The same applies to [[aluminium]], although this metal will float on top of the melt, and will be easily discovered and removed, before it is dissolved into the lead.

=== Magnesium ===
[[Magnesium]] plates are very dangerous in molten lead, because this metal can easily burn and will ignite in the molten lead.

=== Iron ===
[[Iron]] is hardly dissolved into type metal, although the molten metal is always in contact with the cast iron surface of the melting pot.