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Sylvia Rose

Alchemy: Ancient Purification of Tin

Updated: Oct 31

Tin purification is important to various alchemical practices, and a fundamental step in many recipes and formulas. In alchemy purified tin is a regular ingredient in asem, a metal alloy used to multiply silver or gold. To purify tin in ancient times, various methods are used.



Tin has a low melting point, which allows for the easy separation from impurities and other metals. By melting tin, impurities are easily removed, ensuring a higher level of quality in the final product.


Purification techniques and information are from c. 250 AD (Leyden Papyrus). Ingredients and processes are used by metallurgists and alchemists of the time. Many methods can be adapted to modern day. Purification of tin is an essential craft of alchemists.



Liquid metal drooling from a smelting bowl
Liquid metal in a smelting bowl is poured into a mold

Tin has a melt point of 232 °C (450 °F) and can be softened, melted or smelted in a regular fire. Average fire temperatures:


  • Orange flames range from around 1100 °C to 1200 °C (2012 °F to 2192 °F)

  • White flames are hotter, measuring 1300 °C to 1500 °C (2372 °F to 2732 °F). The brighter white, the higher the temperature.

  • Blue flames, or flames with a blue base, are up to twice at hot, with temperature approximately 2500°C to 3000°C (4532 °F to 5432 °F)

  • Violet flames burn hotter than 3000 °C (5432 °F)



fire burns with flames of many colors
hot, hotter, hottest

Purifying Tin - Boiling Method


In ancient alchemy, one fire-refining method for tin is basic concentrated boiling. In this process, impure tin from the smelter or liquation furnace is heated in vessels or kettles agitated by compressed air, such as a bellows mechanism. Impurities rise to the surface as dross.


The earliest forms of compressed air tools, dating back to c. 2000 BCE, are metalworkers' bellows to smelt and forge the ores needed for metal working. Before steam and electricity the bellows can be powered by humans, hand or treadle, horse power, or by a water wheel.



A basic bellows - air is drawn in as the bellow expands & forced out with bellows compression
A basic bellows - air is drawn in as the bellow expands & forced out with bellows compression

Tin is a versatile metal with many uses. One of the seven metals of antiquity, it's commonly sold in the form of ingots or pigs. They're typically bars or blocks of refined or purified tin. Ingots show up as early as 3000 BCE.


Ingots are standardized forms, making them easier for manufacturers to handle, trade and transport. The process of producing metallic tin involves several stages, with most of the production taking place at specialized smelters and refineries from antiquity until today.



The buildings are near mines to streamline supply chain and reduce transportation costs. At the smelters, the raw tin ore goes through a series of refining processes to extract the pure metal, which is then cast into ingots.


Liquation Method


Liquation is a method of fire-refining, specifically tailored for the purification of impure tin and dross resulting from smelting operations. The primary aim of this technique is to isolate impurities with higher melting points than tin itself.



Dross (solids) and slag (liquids) are cast-offs of metal refining
Dross (solids) and slag (liquids) are cast-offs of metal refining. Often they're re-refined to extract other elements.

The metals or materials are put on an inclined hearth in a reverberatory furnace. A reverberatory furnace is a metallurgical or process furnace. It isolates material being processed from contact with fuel, but not from contact with combustion gases.


Materials reach a temperature marginally above the melting point of tin. As the temperature intensifies, the tin begins its transformation to a liquid state, gradually trickling down the inclined surface of the hearth.



Building up the heat
Building up the heat

Molten tin is collected in a container, separating it from the solid residues of the hearth's surface. These solid remnants are then removed and subjected to further processing to extract any remaining elements and enhance overall purity of the tin.


Fire refining can use vacuum distillation. Molten tin is heated in a compact graphite container at elevated temperatures from 1,100 to 1,300 °C (2,000 to 2,375 °F). The process involves application of a vacuum to selectively distill impurities, based on individual boiling points.



16th century smelting furnaces
16th century smelting furnaces

Non-Fiction Books:


Fiction Books:

READ: Lora Ley Adventures - Germanic Mythology Fiction Series

READ: Reiker For Hire - Victorian Detective Murder Mysteries





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