13|Medium |Very bad |Fair |Slight |13 | |in spots | |darkening | 14|Heavy |Consider-|Fair |Slight |14 | |able | |darkening | 15|Extremely|Slight |Fair |Fairly |15 |bad | | |white | 16|Extremely|Advanced |Bad |Surface |16 |bad |and deep | |rough with| | | | |consider- | | | | |able dis- | | | | |integra- | | | | |tion and | | | | |much dark-| | | | |ness | 17|Not as |Less ad- |Fair |Not as |17 |bad as |vanced | |dark as | |No. 16 |than No. | |No. 16; | | |16 | |slightly | | | | |mottled in| | | | |places; | | | | |buff color| 18|Very |Practi- |Fair |Surface |18 |slight |cally | |white | | |none | | | 19|Very |None |Good |Surface |19 |slight | | |fairly | | | | |white | 20|None |None |Good |Surface |20 | | | |fairly | | | | |white | 21|Slight |Slight |Fair |Surface |21 | | | |very rough| | | | |and dark | 22|Medium |Slight |Fair |Surface |22 | | | |fairly | | | | |white | 23|Slight |Bad |Fair |Surface |23 | | | |rough and | | | | |darkest on| | | | |fence | 24|Bad |None |Good |Surface |24 | | | |white | 25|Slight |None |Good |Fairly |25 | | | |white | | | | |surface | 26|Medium |Slight |Fair |Rough and |26 | | | |very dark;| | | | |chalking | | | | |is dis- | | | | |rupting | | | | |black | | | | |coating | 27|Medium |Slight |Good |Surface |27 | | | |fairly | | | | |white |