What you describe sounds like a padding trough that was sold by Kelsey to stack up sheets to be padded. The trough would hold the sheets, then a clamp would be used to put pressure on the ends of the stack. Then the stack would be removed and padding compound would be brushed on the smoothly-jogged edge.
Does it look like the one pictured in this catalog page from the 1948 catalog (look at column labelled “Padding”);
What you describe sounds like a padding trough that was sold by Kelsey to stack up sheets to be padded. The trough would hold the sheets, then a clamp would be used to put pressure on the ends of the stack. Then the stack would be removed and padding compound would be brushed on the smoothly-jogged edge.
Does it look like the one pictured in this catalog page from the 1948 catalog (look at column labelled “Padding”);
https://archive.org/details/KelseyPrintersSupplyBook1946/page/n7
John Henry
Cedar Creek Press