Making fingerprints in metal

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Joined: Sun Aug 16, 2020 5:32 am
Location: Australia

Making fingerprints in metal

Post by Downunder35m »

Sometimes we like something special, something that can't really be explained by someone caught off guard.
Like all these puzzle boxes that are dirt simple once you figured them out.

A lot people already do metal castings at home, be in lead, pewter or for the more advanced aluminium.
But getting really fine details usually means a lot of find detail work.
Imagine you wanted create a handparint in metal.
Usually you make some cast, prepare a mold and get going.
And you get a hand.....
Look closely though and you notice how hard it is to re-create those reallly fine deatils - like your fingerprints.
Doesn't have to be you hands or fingers, literally anything that can tolerate a little bit of heat will do.

The secret, like for wood filling with metla is fusible alloys.
These very special alloys are formulated to have a very low melting point.
Some stay liquid to about -70°C !
Most of them contain Gallium, Bismuth, Zink, Tin.
A few also contain heavy metals like Cadmium or Lead.
For obvious reason the later alloys should not be used or handled on or with skin contact and it is highly recommended to also work with them in well ventilated places while wearing a fine particle mask suited for heavy metals.
So stick to those without Lead and Cadmium ;)

As you can see in this WIKI, it basically comes down to Field's Metal if you go with the classic alloys.
Online though you can find a lot of "magic" metals that are free from heavy metals and with melting points often below 50°C.

To make a casting with these metals all you need a suitable container and a hot water bath, or pot on the stove with water in it.
Once it melts give another minute or two, scrape off any oxides (you see the shiny metal underneath ;) ) and fill it into your warmed up casting form.
Whater is in there will leave a metal imprint.
To create a finerprint it is better tough to do in the surface right when the metal starts to solidify.
To avoid bad wrinkling and trapped air wipe a bit of oil over your finger first - just a film, don't soak it.

Warnings and precautions:
For obvious reasons you should select some alloy that is within your accepted temperature range.
If you get something that needs 115°C to melt and you press your hand in it while still liquid the result will be, well, let's say "unpleasant".
But even just Gallium alone can be a lot of fun.
Big problem with ALL of these low melting alloys is that they also form alloys with other metals very easy!
Means you need to avoid metals throughout.
Especially aluminium and silver are very affected, so don't even bother as these metals won't be usable once exposed to low melting alloys.
Use plastic, wood, glass but no metals ;)
Some claim stainless steel is not affected but while this is partially true for the actual iron in, the nickel, chrome and other things will bond.
Last thing you want is chrome contamination in an alloy you might handle with your hands...
If you know to how to deal with lead when making castings or sinkers you won't have a problem at all.
In case you don't know, just check some of the many Youtube videos out there where people also expplain handling and "cooking" risks.
Exploring the works of the old inventors, mixng them up with a modern touch.
To tinker and create means to be alive.
Bringing the long lost back means history comes alive again.
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