***UPDATE***
I had some time to work on the Camry today and test some of the surfaces for roughness.
The car had some light dust on the surface so I decided to use DP Waterless Auto Wash with a Shine & Buff Waterless Wash Towel to clean the surface. I did the baggie test on the roof after the surface was dried and I could feel the surface was rough, though not as rough as the hood.
I started off with the same sequence I used on the hood and that was with the Nanoskin AutoScrub Fine Grade Wash Mitt and ONR as the lube. This time I used the correct dilution ratio for using as clay lube, as recommended by forum member
allenk4, and that is 2 ounces per gallon, which comes to 1/2 ounce per quart. I sprayed the surface with the ONR and rubbed the Nanoskin Wash Mitt lightly over the surface. I used about as much pressure as you would when washing the car with a wash mitt. You can feel the Mitt removing the contaminants as your going along.
After the surface was dried I did the baggie test and the surface felt very smooth. Smooth enough that there was no need to do any further scrubbing.
I decided to try the ONR diluted the same way I had done before, which was 2 ounces per quart, on the other half of the roof to see if that had any affect on the ability of the AutoScrub Mitt to remove the contaminants. I used the same rubbing pressure as on the other half of the hood. (You can see the darker color of the mix due to more ONR).
After the surface was dried I did the baggie test and the surface felt very smooth. Just as smooth as the previous section used with a lesser concentration of ONR.
In my case the higher dilution ratio of the ONR did not seem to have any affect in removing the contaminants. It may be that the proper dilution ratio may work better on surfaces that are more heavily contaminated.
I decided to check some other areas of the car such as the trunk, front quarter panels, back quarter panels and every area came out very smooth with just using the Nanoskin AutoScrub Fine Grade Mitt and ONR as the lube.
In conclusion, there may have been something else on the hood such as sap, as mentioned by forum member
swanicyouth, or it could be that the contaminants that were on the hood have embedded into the paint over time due to the heat from the sun together with the heat underneath coming from the engine.
It could be that Iron-X or something like Tarminator or even wet sanding may have eliminated the roughness but the hood is now Opti-Coated and I'm going to leave it the way it is. You can't see the roughness, the only way to tell is to do the baggie test. Besides, I'm very satisfied the way it came out.
