A thumb marked with indelible ink during Wednesday
(Photo by Gallo Images/Lefty Shivambu)
  • Some political parties say a failure of the "indelible" ink used to mark voters' thumbs allowed double voting, and the IEC is investigating.
  • The pens used cost R2.7 million and were bought from a subsidiary of Bidvest, tender documents show.
  • The formula of the ink used is a secret, but an expert says cutting corners when it comes to silver can be one reason "indelible" ink turns out to be not so indelible.
  • For more, go to Business Insider South Africa.

The Independent Electoral Commission (IEC) has said it will demand answers from its supplier about what could have gone wrong with the "indelible" ink pens used in Wednesday's election – and which some parties say were not indelible at all.

The ink used to mark the left thumb of every voter is supposed to remain visible for at least seven days. But according to various reports the marks were easy to remove, and political parties have lodged official concerns about the double-voting they believe may have resulted.

Just what may have gone wrong with the ink is not yet clear – and the formula used is strictly secret by design – but both experts and tender documents suggest there are multiple ways indelible ink can fail, especially if you skimp on the silver. 

See also: Here's how house prices reacted to previous South African elections - and what you can expect this year

Tender documents show that the IEC awarded a tender worth R2.7 million for the supply of the pens in February 2018. The supply contract went to Lithotech Exports, a division of the JSE-listed Bidvest, which beat out six other security-product and printing companies.

Neither Lithotech nor its parent company Bidvest could be reached by phone, email, or WhatsApp on Thursday morning.

At the time the IEC estimated it would need a total of 167,400 indelible ink pens over the two-year period of the contract, of which a small number would be used during by-elections while the 2019 national and provincial election would require a stockpile of 165,000.

Those numbers suggest a per-unit price of just over R16 per pen, a price that raised eyebrows among experts as low, perhaps implausibly so.

According to tender documents the pens had to be capable of delivering a mark that remains "easily visible for a period of at least 7 days". 

"The indelible finger marking ink pens must be a unique ink with an inherent ability to withstand removal by washing, rubbing, or other mechanical means, after application," the IEC told its bidders.

It also demanded secrecy.

"The formula of the ink must be kept secret, and must not be readily commercially available or reproducible," the tender specifications document read."

Because of the specialised nature of the product its bidders may have to work with third parties, the IEC said, and any such arrangements – such as importing ink or completed pens – had to be declared in bid submissions.

Tender documents suggest one possible reason for the failure of pens: shelf life. According to the IEC indelible ink can typically be stored only for around 6 months.

But silver nitrate is more plausible explanation according to Justin Howard of specialist voting-ink manufacturer AP Africa, which has previously supplied the IEC but was not involved in the current contract.

Voting ink pens can fail because of mechanical problems with the pen itself, or because the ink is not properly applied, or even if voters' fingers are oily enough, Howard said. 

If everything else is working properly, however, a low level of silver nitrate is worth investigating.

Like with baking, Howard said, good ingredients are key, and silver nitrate is "the main active part" of the formula, with a recommended 13% minimum in any ink intended to be hard to remove. 

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