There is no white in a black and white photograph
The phrase "There is no white in a black and white photograph" is a philosophical or artistic statement rather than a literal truth. In black and white photography, the absence of color doesn't mean the absence of white. White is represented in a black and white photograph by the absence of any pigment or shade, essentially where the paper or the background is left untouched by the photographic process.
In a black and white photograph, the presence of white areas typically represents the brightest parts of the scene being photographed. These areas may be highlights, reflections, or areas of direct light. So while there might not be the color white in a black and white photograph, there certainly can be areas that appear white due to the way light and shadow are captured in the image.
If the paper used for a black and white photograph has colored geometric shapes instead of being uniformly white, it would affect the appearance of the photograph. The areas of the image that correspond to the colored shapes on the paper would also take on those colors, resulting in a tinted or colored effect in those regions of the photograph.
So, unlike traditional black and white photography where the paper color doesn't directly influence the image, in this scenario, the colored geometric shapes on the paper would introduce color into the photograph, affecting its overall appearance.
Everything you see on my site is handmade artwork. The watercolours are 17 x 17 cm 6,7 in, created using artist-quality colors and quality cotton paper. The oil paintings are 40 x 40 cm 15,7 in, painted on canvas and coated with light-sensitive material, all done by hand without the use of computer technology.
Of course the original does not have a watermark, it is only for protection on the web