You have what is called 'black sooty mold' on your camellias. That, however, is not the problem! Black sooty mold is a harmless simple mold that grows exclusively on the sugary excretions of sucking insects. It is always a one hundred percent indication that pest insects are either on the affected plant, or above it! In the case of camellias, I would bet money that you have a serious outbreak of tea scale. Turn the leaves over and you will find very tiny brown specks and a white fuzzy coating in some cases. Tea scale. Once you get rid of the scale insect, the black sooty mold will disappear on its own. The attached link illustrates a bad infestation of active tea scale. If we were to turn the leaf right side up, we would probably see black sooty mold. BSM, by the way, will also grow on lawn furniture, car roofs, etc. if the excretion drops from insect infested trees. Here is a link that might be useful:

30sVintage - What you have is a mix of leftover furniture polish and dust, baked together. Have you tried mild soap and water? If that doesn't work, try mineral spirits on a soft cloth. Wipe on a generous amount, let it sit and then wipe it off with a clean cloth. Test in a hidden area, but mineral spirits usually doesn't affect the finish of a piece. As you found, anything oily just spreads the oily dirt around. The mineral spirits can dissolve old oils and grime.

I sanded the table but that was b/c the top was in rough shape from 10 years of abuse. Then I used the roll on type of paint for the table (it comes in quart cans). I used a foam roller which left a smooth as silk finish. I didn't sand the chairs b/c it would have been a major pain in the rump. Instead I used a liquid deglosser which cleaned the chairs and took off the glossy part of the wood which allowed the finish to have some 'teeth' which would help the spray paint adhere. What impressed me the most about this paint is that the finish between the quart can and the spray can are exactly the same! It's impossible to tell the difference b/t the two. I honestly can't say enough good stuff about the paint. I did an armoire last year and it still looks great. The coverage is phenomenal. I did two or three coats on the pedestal (I can't remember the exact number b/c I did it last year while allowing myself to digest the color a bit before moving on to the chairs). I did put four coats on the table top and skirt though b/c it will get more abuse. I only put two coats on the chairs. DH thinks that I should put another coat on them but I'm actually kind of hoping that they will age and develop a bit of a patina. Please don't pay any mind to the condition of the house. We are currently in military housing and will be moving into our new house next month . . . so we've been purging, organizing, etc. I got rid of the rug under the table which has revealed the most terrible govt tile floors that were installed back in the 40s. Yuck!

Yikes! Having a numb finger for two weeks would freak me out. Glad it's gone! I will definitely get one of those doodads. Did you spray primer on it first? I remember now, we had beautiful cool Spring days and that's when I was working in the flowerbeds so much, and suddenly it got hot with high humidity and stayed that way until this week. I melt in humidity. I love the green you used, but I'm thinking it would be too dark for that corner of the porch. I'll probably look for ideas online.