I received three near empty OEM 4900 carts, Photo Black, T6531, 200 ml etc. Took one apart. There is no pressurised chamber with an ink bag inside, no air inlet either. It surprised me as I had some 3880 carts that show the construction for pressurised ink feeding.
Paul, was there no written instruction with the images for refilling the 10000 carts? I did send the images and the text to John Dean many moons ago.
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Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
April 2014, 600+ inkjet media white spectral plots.