A minor correction to the translation:
3,26 3,29 in which a blade was inserted, spreading the emulsion over the paper
3,26 3,29 to which a wide brush was attached, spreading the emulsion over the paper
As there is no modern type "coating blade" visible, but it appears some kind of brush. Actually the Dutch narration here is inconclusive, and uses a very unusual word in the context of the footage displayed.