When I bought my 2003 Featherlite trailer last July from the dealer it was pure, sparkling white. I took good care of it last year, but it isn't under roof. I washed it today, the first time this year, because I'd picked up mud from our recent rains. And I notice that now the white side of my trailer are yellowed - not the pure sparkly white that they used to be.

Is the colour change caused by precipitation? Will an acid wash remove the dingy yellow tone, or does an acid wash only sparkle the silver aluminum lower parts? The silver is dingy looking now, but it bothers me less than the white.

One last thing. I had my horses at the vet a month ago, and my gelding had a tooth removed (it was a baby tooth, and coming in crooked) He rubbed his face on the side of the trailer, on the white siding, and I didn't wash off the blood right away. Truth be known - I sorta forgot about it. Today when I went to wash it off, I discovered that its not just a dry streak of blood anymore, it wouldn't wash off even with warm water and me scrubbing with a brush. It's almost as though its made a stained film, I think I can scratch it off with a fingernail if i work at it. But normally blood can be washed off - it can just take some scrubbing (I can votch for that since I'm a nurse) So what's with the way it became a stain on the painted aluminum?

Guess I need to get some education on cleaning my trailer, I thought I was doing an okay job, but it certainly isn't as nice as it used to be!

You might try this:

http://jmtdistribution.com/

or www.streakmaster.com contact either one of those guys and they can probably help you out.Yes,they sell their own products,they are all very good products.

Trailer manufacturers purchase the aluminum siding  prepainted from several sources. They can specify what type of paint, and the colour they need. Their costs will depend on what they have chosen. The most common finishes are acrylic and polyester painting systems. The polyester is commonly used because it is durable and has good adhesion when the metal is cold bended. The acrylics have the same properties plus more resistance to stains, colour retention and UV damage. Accordingly, the acrylics cost more and are not universally used.

This is the reason some people will have an easy time cleaning their trailers, while others using the same materials, find a more difficult experience.

There are many postings and threads available in the SEARCH files about various materials that remove stains. I would start with the more popular ones that Crowleysridgegirl has mentioned. If they don't work, you can use products that are designed in the aircraft and marine fields.

Do not use an acid wash on any paint product. You could irreversibly damage the finish that could result in re spraying the whole trailer. I also would not use an aggressive polishing compound and machine buffer. The paint is only a few thousands thick, and can be quickly worn away by aggressive compounding.

Once the stains have been cleaned, if your are a stickler for the optimum finish, a clear coat finish can be sprayed over the present paint, that would eliminate most of any future discolourations.