This section is from the book "The Potato: A Compilation of Information from Every Available Source", by Eugene H. Grubb, W. S. Guilford. Also available from Amazon: The Potato: A Compilation Of Information From Every Available Source.
Fancy Potatoes. One variety ripe, sound, smooth, clean, bright, even, run of good size, true to type, not over 5 per cent., but would run over screen two inches in clear:
Choice Potatoes. One variety, ripe, sound, not over 5 per cent. scabby, wormy or knotty; fairly clean, bright and even in size; not over 10 per cent., but would run over screen two inches in clear.
No. 1 Grade. One variety with not over 5 per cent. mixture of same color, or 2 per cent. of other color; fairly ripe for date of shipment; not over 15 per cent. scabby or wormy; not very knotty or muddy; fair size, run over screen one and seven eighths inch in clear.
No. 2 Grade. Not over 50 per cent. scabby, wormy, knotty, or green; not over 5 per cent. unsound or that would go through a screen one and seven eighths inch in clear.
The grower who sorts poorly, or uses a screen less than one and seven eighths inch in the clear, or who does not throw away his poor sacks, or who fails to do that little job of grading and to provide that foot ditch and wasteway, injures his neighbor even more than himself.