Carol Hardijzer, the South African photo historian (with particular interest in South African photographs from prior to 1915) replied as follows: ''With regard to the Potgieter photograph – The photograph is highly unlikely to be that of the Voortrekker leader Potgieter, based on the following reasons:
- The images is clearly a portrait image pasted on a piece of carton (a format known as Carte-de-Visite);
- During 1851, the Carte-de-Visite photographic process was still no patented. This format was only patented in France during 1854 and would only have been in use in South Africa from very late 1850’s onwards (which then clearly would put the image under discussion out of range);
- The photographic format in use between from the 1840s until early 1860s would have been the daguerreotypes and ambrotypes (Images on glass placed in beautifully designed cases). It is highly improbable that the image under discussion would have been reproduced from a glass format photograph into a paper format version.
Considering that Potgieter passed away during 1852, it is therefore my suggestion that it is improbable that the image under discussion is of the Voortrekker leader Potgieter. The image would date from around 1865 in my view – It may however also be of a Potgieter. Happy to discuss further. I take the liberty of attaching one of my articles (on the carte-de-visite format) recently published on our local theheritageportal.co.za : http://www.theheritageportal.co.za/article/south-african-cartomania-photographic-phenomenon"