Einstein first made predictions about the phenomena in 1912 but did not publish an article on it until 1936
Color Grey Dry Time 40 seconds in a Pilot VP medium nib on Rhodia Flow Dry Shading Medium Sheen No Shimmer No Limited Edition No Water Resistance Medium Iron Gall No Pigmented No
Noodler’s Bad Belted Kingfisher from the Bulletproof collection is a deep blue ink
Ink Name Honey Country of Origin Germany Color Yellow Dry Time 30 seconds in a Pilot VP medium nib on Rhodia Flow Average Shading No Sheen No Shimmer No Limited Edition No Water Resistance Low Iron Gall No
the marble will fall vertically and prevent the ink to flow back
Noodler's Waterase Blue Size:4ml Sample Einstein first made predictions aboutBlue ink that washes away from plastics with water, yet is permanent on paper, from Noodler's, made in USA. Comes with eyedropper cap. Bleach and UV resistant (on paper) Archival and fade resistant (on paper) Impervious to lasers, alcohols, and solvents (on paper) Water resistant (on paper)