This 4-color reference spot sheet (8.50 by 11.0 in.) shows five spots rated No. 1 through No. 5. A sample of residual fuel is put on a test paper, placed in an oven and heated for an hour. The resultant spot is examined for evidence of suspended solids and rated for cleanliness and compatibility against the reference spots on the adjunct.
Adjunct to D4740 Test Method for Cleanliness and Compatibility of Residual Fuels by Spot Test