The competition puzzle
A novelty idea! Developed around 1935 by our father. Two puzzles, in a solid colour. Sawn together, so the 100 pieces in the two puzzles are 100% identical.

To make things even more difficult: they were separated in 4 pieces before they got their coloring; therefore, half of the pieces are upside-down!

The cartophote
(professional use of the jig-saw)
In the years 1953-1957 prof.dr. E.W. Hofstee of the Social and Economical Geography department of the Agricultural Highschool in Wageningen got in touch with my father. He had to write a book with a lot of changing maps of the Netherlands. What he needed was several maps of the country, divided in economical geographical areas (EGA). To each piece a statistical value had to be given, in various grayscales. Drawing these would be an enormous task. With a jigsaw-puzzle this would be a simple job. Drawing a chart would cost approximately fourteen days. With a jigsaw (cartophote) this could be done within a day.
A basis was made of thick blockboard. In 1.5mm airoplane triplex the outline of the area was attached. The separate areas were outlined and given numbers. The EGA-parts were also sawn out of the same kind of triplex, in a pile of eight different grayscales and patterns, plus solid black and solid white. Another option was to choose for patterns and colours, to show the differences compared with an earlier date. Colours used were white : no change; red : negative; blue : positive.

The patterns were screen printed on the wood. The Dutch 'Central Bureau of Statistics' coöperated to make the most ideal patterns, so that all patterns remained sharp and un-blurred. The CBS wanted the lines of the pattern in the same plane with the different patterns, our father opted for a slight skip to improve distinction. An other problem was to find a saw-blade thin enough (0,1mm) to keep the pieces in place with the cartophote standing uppright. Also, the glue in de airoplane triplex caused most of the sawblades to break frequently. The best blades were finally found in the German Ruhr-area, but still many blades per cartophote were necessary.

The eldest son Frans Jr. attended the Amsterdam Efficiency fair in October 1968 where the cartophotes were introduced for a large market. Shown here is a rare occasion where Frans Sr. himself was present.

Our father built a simple cabinet with drawers with numbered compartments, corresponding with the area numbers. The pieces were also numbered (on the back). Once the map is laid, there was a legend where you could check the value of each pattern. Also, a transparent overlay sheet was added with the regional information.
After that, it was simple to make photographs of the whole map in all different possible options. Some sales organisations and provincial services were interested. Again, time was not on my father's side: although a reasonable number of cartophotes was sold the arrival of the personal computer made further growth of the project inefficient and economically uninteresting!

Nice to know: the chief of the drawingroom of the Dutch 'Central Bureau of Statistics' refused to buy cartophotes. The reason might have been that he saw himself reduced from head over twenty draughtsmen to supervisor over a nurseryschool of maybe five jigsaw layers.

As far as we know, this was worldwide the only professional use of the jigsaw!

Puzzle challenge
Every now and then somebody dropped a pile of puzzles on the floor, during transport from the saw-shop to the packaging department. Those puzzle pieces were not thrown away; they were put in a box and taken home. There were always a couple of the seven Klaus-children interested in putting them back together again! A falling stack was usually fifty to one hundred puzzles so you soon faced 6,000 pieces. Maximum ever was 20 puzzles of 600 pieces each: 12,000 pieces of identical puzzles depicting a view on a harbour with lots of blue, grey, bluish grey and greyish blue!
First selection was on colour and pattern, and starting to find a corner piece, p.e. bottom right. Then select the almost identical corners (puzzles were sawn with three to five at the same time, so almost identical) then the real job started. If you found a piece that did not fit perfectly it was probably from the neighbouring puzzle. After completion, all puzzles were turned backside up because, as they were sawn with some together, it was possible that a piece had landed in the wrong puzzle, so they were inspected on the correct pattern of the grain.

Selection of pictures
Our father did the selection of pictures himself, both for childrens puzzles as for those for frown-ups. It was a time consuming job for which he searched big books, delivered by the company of D.van Os & Son. It was an important job as chosing the wrong pictures meant less sales!

Work for others
In February 2021 the question was put to us by Kerstin Witzenhausen (who also supplied the pictures for this paragraph) if a puzzle by Sala from Berlin could possibly be sawed by Kolibri in Bussum. That was difficult to answer this with certainty.

Indications are available. Frans can remember that our father once mentioned the name Sala a long time ago. The way of sawing is also certainly identical to the one used by Kolibri. The size of the puzzle, 27 x 35 cm (appr. 11" x 14"), is thus that it could be necessary to saw the puzzle in two parts because the danger was real that corner pieces would come outside the border of the work area and drop on the floor. The puzzle by Sala has indeed been sawn in two parts. The first cut runs between the eight and ninth piece from top to bottom; the horizontal cuts are interrupted there.
And around the second world war work for others was regularly done. Obviously this puzzle was one of those.