Garage door "dirt" not coming off

I am still learning here but have researched a lot. I had a job yesterday where the top section of an aluminum garage door would not come clean. I have seen this a lot where the upper sections of siding and garage doors, typically these sections are covered by an overhang, have a caked on dirt that is really stubborn to remove. I did make decent progress but it still looked dirty when I was done.

In this home yesterday the garage was facing north-west and I was there in the early evening so the garage door was hot from the sun.

My attempts were:

  1. rinse the aluminum garage door to cool it down
  2. tried SH - .75% - since it’s not organic growth this did nothing
  3. Tried LA Awesome - diluted then straight - showed promise but I needed to scrub a lot and I was getting close to bare aluminum.
  4. Tried diluted Gutter Grenade - same results as LA Awesome

I have not tired Purple Power but wonder what the difference in PP and LA Awesome is.

How do you guys deal with this? Thanks!

This in not the house I did but a good example.


Thanks for labeling the roof. I was a bit confused at first, I thought it was a deck lol


Man we have a ton of that here in Louisville, atmospheric crud (fallout) just collects under eaves and doors. I’m not much help though as all I use is some type of degreaser which you already tried.

Aluminum brightner - will make it look new Pump spray a lite coat on it, let dwell few min and rinse with medium pressure fan spray. I use my m5ds so about 500 psi


Thanks Rick! I will give it a try. Does it matter if you pump spray on the dry garage door or should the door be misted first? Thanks again!

Either will work. If it’s wet need to put more on it though and a little longer dwell.

Which brand aluminum brightener do you recommend?

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This stuff cleans the black residue or tiger striping on gutters. I’d imagine it work on this same application.

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