Hi and welcome to Taiga Bonzai, in this post we discuss the problems of alkaline staining or calcium build up and how to remove these marks from glazed and unglazed ceramics. But first it would be prudent to discuss some of the chemicals used in tap water that contribute to the problem.

Introduction – tap water having a pH range from 6.5 to 8.5 (depending on your particular region) contains various chemicals some thought to be beneficial, but scientific tests have shown this conception to be a misnomer. For example, Fluoride (F) thought to assist in the reduction of tooth decay is a neurotoxin an endocrine disruptor, able to damage the thyroid gland, calcify the pineal gland and interfere with bone formation. Many countries have now banned its use due to health risk.

Other toxic chemicals – include Chlorine (CI) a strong disinfectant added to drinking water as a purification technique, it is a reactive chemical that bonds with water, including water in the stomach producing poisonous hydrochloric acid. Mercury (Hg) a naturally occurring element usually a bi -product of mining and industrial practises. Arsenic (As) used in a multitude of industrial processes, Lead (Pb) major toxin that still exists due to corroded piping systems that is extremely toxic.

PCBs (polychlorinated biphenyls) are chemicals used for industrial purposes such as insulation, machinery, oil, paints, adhesives, electronics and fluorescent lights. Perchlorate (CI04) HCB or Pentachlorophenol (C6) and DDT (C14H9Cl5) (Dichloride-Phenyl-Trichloroethane) all have detrimental effects. As do modern insecticides and herbicides including Glyphosate which, are highly toxic, to read the full post on this topic see ‘article 36 – a teaspoon of vinegar’ part 2.

Acidic cleaning – acid cleaning agents are used to remove scaling and other inorganic deposits. Normally, the active ingredients in such solutions include chelants and mineral acids along with corrosion inhibitors and surfactants. Acid cleaning is a useful method to clean materials and wash away corroded parts, the most commonly used cleaning agents include hydrochloric acid, also referred to muriatic acid. Other substances include sulphuric, vinegar (acetic) and citric acids, for hard surfaces, which can assist in removing build-up of calcium deposits.

In brief the potency of the above mentioned acids, Hydrochloric acid H⁺Cl⁻or H₃O⁺Cl⁻ is an aqueous solution of hydrogen chloride, a solution with a distinctive pungent smell of ‘stale almonds’ and classified as a strong acid. It is a component of the gastric acid in the digestive systems of most animal species, including humans; but is still highly toxic due to its concentration.

Sulphuric acid known in antiquity as oil of vitriol is a mineral acid composed of elements that include sulphur, oxygen and hydrogen, with the molecular formula H₂SO₄. It is a colourless odourless viscous liquid that is miscible with water. Hydrochloric and Sulphuric are arguably the most potent chemical agents used in acidic cleaning of alkaline contamination especially on pipes and drains. If used undiluted will have instant effects, hence protective clothing should be used at all times.

Acetic acid, systematically named ethanoic acid is an acidic, colourless liquid and organic compound with the chemical formula CH₃COOH. Vinegar is no less than 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water and other trace elements. Vinegar is extremely effective when added to tap water which if left to stand for two days softens the hardness of tap water. (see article 35 ‘A teaspoon of vinegar’)

Citric acid an organic compound with the chemical formula HOC(CH₂CO₂H)₂ is a colourless weak organic acid occurring naturally in citrus fruits. In biochemistry, it is intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms. Although these two acids (vinegar & citrus) have the ability to clean alkaline contaminated items, they lack the potency to remove all traces moreover, using such in large quantities would not be cost effective.

Recommendations – hydrochloric acid H⁺ Cl⁻ or H₃O⁺ Cl⁻ and sulphuric acid H₂SO₄ can be purchased at most hardware or large supermarket chains however, obtaining the latter might pose some difficulty hence an explanation as to why it is needed due to its history of misuse. According to Patrick Knox in his article in the UK SUN newspaper 14:17, 24 May 2018 Updated: 14:18, 24 May 2018 he states that “in the UK (H₂SO₄) has been used by psychopathic sadists to inflict agony and disfigurement on their victims” thus a license to purchase is now required.

Research – after some enquiries as to what is available, we found that here in Scandinavia hydrochloric acid can be found almost anywhere and can be purchased quite easily as permits are not required, hence the following product was obtained a – 4 litre container for €24,95. After a few experiments to find the correct combination of the acid solution and water, a few tests on chrome taps and other faucets were cleaned with all alkalinity and calcium build up removed.

The next step was to experiment on bonsai ceramics to test our theory, image 1. depicts a bonsai pot drip tray with a large heavy alkaline calcium build up over a two year period. To attempt to remove this unsightly mess via the use of metal instruments would be unsuccessful moreover, the risk of damage to the glaze would be inevitable. A solution using 50% hydrochloric acid and 50% water was made and the tray was submerged for 30 min.

After the alloted soaking time (30 min) the tray was inspected and all traces of alkaline calcium build up were removed, the solution itself was all that was required. Hence the need for brushes or scouring pads including wire wool were not required, the tray was then rinsed with clean water to remove any traces of the solution then dried. Image 2. shows the result of the cleaning process.

Power of acidity – in looking at the dirty drip tray one might think that “if alkaline can do this to ceramics, what effect does it have on the human stomach” in short the answer is not much. The human body has various fluids containing different pH values. Food when consumed goes through a process the upper part of the stomach has a pH of 4 to 6.5, while the lower part is highly acidic with a pH of 1.5 to 4.0. It then enters the intestine which is slightly alkaline, with a pH of 7 to 8.5, hence the body’s fluids can easily adapt to changes in alkaline and acid and vice versa.

Different manufacturers – there are various manufacturers that produce acid cleaner the world over and all will have different brand titles depending on what name/s they are assigned. But providing the label states that it is muriatic acid – hydrochloric acid H⁺Cl⁻or H₃O⁺Cl⁻, this is the chemical we prefer to use because of (a) its ability to remove alkaline calcium build up (b) it is relatively safe if used according to the manufacturer’s instructions opposed to the more dangerous sulphuric acids.

Disclaimer notice – as stated there are similarities in hydrochloric acid production in animals and humans via their digestive systems, but manufactured hydrochloric acid is a concentrated toxic poison and should not be used on household appliances regardless of the amount of dilution. For these use Bicarbonate of soda, vinegar or citric acid, which is safe. Until next time, BW, Nik.