| Acid Rain |
1/16"-1/8" |
Circular spots with depressed centers. Etching
detectable by touch |
Acid Rain |
| Alkaline Spots or Water Spots |
1/8"-3/4" |
Roughly circular, fuzzy white edges, not
depressed, appear to be within the paint |
Alkaline Rain, hard water sprinklers |
| Jet Fuel and Diesel Fuel |
1/16"-1/8" |
Circular, but not depressed centers. May
appear to be within the paint |
Jet Fuel spray from aircraft, truck or train
diesel exhaust |
| Bee Spots |
1/8"-3/16" |
Roughly circular, depressed centers. Primer
exposed after sufficient time (3days) |
Bee droppings (or wasps) |
| May Fly Spots |
3/16"-1/4" |
Crescent shaped pits in paint. Can eat through
to bare metal in 4 days |
May flies, contain part of insect body |
| Bat droppings |
1/16"-1/4" |
Teardrop shapes usually 3 to 4 in a line
gradually decreasing in size. Paint may be pitted after 3 days |
Insect eating bats |
| Ferrite Spots |
1/8"-3/8" |
Small black granule at the narrow end of
a teardrop spot with a fuzzy edge. Paint pitted near the back brake linings
attracted by a magnet |
Ferrite particles from train & truck.
Blow off from stack fallout stacks at foundries |
| Stack Fallout-Type A |
1/8"-3/16" |
Roughly circular, depressed centers, may
have small particle near center of spot particle + H20-pH2.5 |
Stack emission from power plant & factories
with coal |
| Stack Fallout-Type C |
1/4"-3/16" |
Roughly circular, depressed areas with small
spatulate particles, pale yellow in color. Fuzzy edges, circular, pitted
through paint in 24 hours |
Stack emission from corn processors for
liquor/vitamins. Stack emission from plastics manufacturers |
| Stack Fallout-Type N |
1/16"-1/8" |
Roughly circular, some depressed areas with small
gray to black particle |
Paper & news print emissions |
| Bird Droppings |
1/2"-3"+" |
Large whitish spots dappled with irregular
dark marks. May be highly acid or alkaline depending on diet |
Local birds 3000 species U.S. |
| Tree Sap |
1/8"-1"+" |
Large, irregular, sticky spots. May be acid
or alkaline. Pine tree sap is the worst, contains resins |
Local trees |
| Paint Overspray |
1/8"-3/16" |
Overall spray pattern or splash pattern
in the color of the paint used |
Construction work, bridge repairs, painting
operations |
| Cement Spots |
1/4"-1"+ |
Overall splash or spray pattern of cement
and/or concrete |
Construction operations |
