There are sometimes concerns expressed about
the use of sal ammoniac to clean the tips of soldering irons. My conclusion is that there are no elements
of the block that will affect the copper plating of the soldering iron
bolt. It is safe to use this as an occasional cleaning method of soldering iron bolts. This is based on the following
information.
What it
is
The common term, sal ammoniac, refers to the
chemical ammonium chloride. Sal ammoniac
is the archaic name
for it. The Romans named it from the ammonium chloride deposits that they
collected from near the Temple of Jupiter Amun in ancient Libya. It is found as encrustations around volcanic fumaroles, guano deposits and in burning
coal seams. Notable
occurrences include Tajikistan; Mount Vesuvius, Italy; and Parícutin, Michoacan, Mexico.
Wikipedia
Ammonium chloride is the product from the
reaction of hydrochloric acid and ammonia.
Ammonium chloride is obtained as a by-product in different chemical
processes. It consists
of white crystals that are also available in rods or lumps. The substance changes directly from being
solid to gas with no intermediate liquid state. The gas does not consist of
ammonium chloride molecules but ammonia and hydrogen chloride. This shows that
the salt decomposes easily. When stored, ammonia is continuously emitted and
the substance gradually becomes more acidic.
https://www.fishersci.co.uk/shop/products/ammonium-chloride-99-6-analysis-acs-acros-organics-3/p-3586389
Safety
It is widely used in human medicines as an
expectorant, diuretic, etc. and in veterinary medicines to reduce gallstones,
so it is a relatively benign material in relation to human health.
There are some hazards though. It can cause serious eye irritation on
prolonged exposure, and is harmful if swallowed. The precautions are to avoid eating, smoking,
and drinking when using it. Use gloves
and eye protection if you are using it for extended periods. If it gets into your
eyes, rinse with water for several minutes. https://www.fishersci.co.uk/shop/products/ammonium-chloride-99-6-analysis-acs-acros-organics-3/p-3586389
It is highly soluble in
water, and forms a slightly acidic solution. Its
main characteristic that you need to protect yourself against is that it
vaporizes without melting at 340 °C to form equal volumes of ammonia and hydrogen chloride
gas. https://www.britannica.com/science/ammonium-chloride
The amounts of the gas are small when used to
clean soldering irons, but as the gas forms hydrochloric acid in contact with moisture,
you should use dust masks rated for inorganic acids. The amounts are small and generally only cause
sneezing and coughing upon contact.
The primary hazard is the threat posed to the environment. Immediate
steps should be taken to limit its spread to the environment.
Uses
In addition to medicine, it is used to
clean soldering irons. It has uses in jewellery-making and the refining of
precious metals. Sal ammoniac has also
been used in the past in bakery products to give cookies a very crisp texture. In some areas, particularly Nordic countries and the Netherlands, it is still
widely used in the production of a salty licorice candy known as Salmiak, or Salmiakki. Formerly it was used as the electrolyte in
dry batteries. It has uses in fertiliser
as a source of nitrogen mostly for rice and wheat crops in Asia. It is also an
ingredient in fireworks, safety matches, contact explosives, cosmetics and many
other applications.
Conclusion
Although there are some mild safety
precautions that need to be followed, there is nothing in the sal ammoniac
block that can harm the copper coating of the soldering iron tip.
