Topps used the Kodak Flexichrome process in earnest through their 1962 Baseball issue and then sporadically after that for another several years as needed. It eventually became an unnecessary process and in fact the Flexichrome product line was discontinued in 1961 by Kodak. Used in combination with some airbrush techniques, you can usually spot a Flexichromed card a mile away. Here's a couple of examples you may know.
1959 Topps #468:
See how "soft" the pictures look in the triptych? That's Flexichrome.
Here's #130 Lou Jackson from the same set. If Topps has a sharp color image they would use it and forego the coloring process. You can see the freckles on his face this shot is so clear:
Compare that to this 1960 Rookie Star, #131 Ed Hobaugh, who looks decidedly unnatural:
There is a bit to unpack here. The sticker on the bottom lefty indicates this was from the famous 1989 auction of original Topps production materials, and indeed it was lot # C10 on page 65 of the catalog:
The 17/049 notations must have been a storage location used prior to the auction. Note the bitchin' Topps Auction stamp in the upper right corner:
Woody Gelman himself hand wrote the player identification...
...and the instructions to the Flexichrome artist:
The upside down writing on the right hand side of the backing board is a little harder to puzzle out and are in a different hand, possibly that of the artist coloring the piece. Sizing instructions are aboard too and that line at the end of the bottom pointing arrow here (pointing up on the original) is where the image was cutoff for the card:
Take a gander at the two left side line markings in red, laying out some macro geographic color real estate levels I think:
And the piece de resistance:
I love how you can see the green and blue Flexichrome paints oozing out from the original, like blotted watercolors. A lot of masking went into the colorizing and it looks to me like the piece has slipped up a hair off the backing based on how the lines match up (note the one to the left indicting the top of the grass line and the 1 1/2 indicator arrow atop the right side).
What a fabulous piece of Topps history! Here's what all that massively involved work produced, you can see the crop atop Howser's cap indicated by the line shown above (it got cropped a little on the left and right sides, even if you account for the framing neatline: