washing painted aluminum siding

[tomsteve]

i somehow let myself get talked into helping wash an aluminum sided house in which the siding was painted a while ago.. it appears the paint on the siding is in good shape- just dirty. it hasnt been washed in quite a few years.
any recommendation on a cleaner/ soap to use?

[Oldwood2409]

Cannot recommend any cleaners but I do have one thing NOT to do. DO NOT use bleach or bleach products as is will corrode the aluminum and cause the coating to bubble and in some cases cause significant corrosion of base metal. (This recommendation is from a siding installer and personal experience from damage left behind by former owner of my current house)

Greg

[tomsteve]

thanks, oldwood. bleach was out of the equation off the get go.
im going to spot try properly diluted simple green on an inconspicuous area and see how it works. ive used it on an aluminum sided motor home ( original color- not painted over) that was parked under trees for a few years. worked pretty darn good on that. 
beings how the siding on the house has been painted, we shall see what happens

[Snipe Hunter]

Aluminum in general is hard to paint but if the existing paint on it is good, you need to adhere to the paint. Assuming you want the new paint to stick, you'll want to scuff the existing paint which will take longer and more muscle than the painting itself. I know this doesn't sound pleasant but it's really necessary to get a good bond. You'll want to use gray Scotchbrite. The red Scotchbrite is too aggressive and will blow through the thin paint. I'd use a mild dish soap and water mix so you'll be washing the same time you are scuffing. You'll only need 2 or 3 drops of dish soap in a quart spray bottle of water. You'll also want a bucket of water mixed in the same ratio to rinse out the Scotchbrite in to reduce clogging. The soap also acts as a lubricant so it will take less effort to scuff and help reduce the Schotchbrite from clogging. If you use too much soap, it will be hard to rinse off the siding and you'll get adhesion problems. Once scuffed, rinse off the siding real well. I'd also talk to a paint dealer like Sherwin Williams about the right paint and primer if necessary. Rent a sprayer. It's a lot of work, is the color really that bad?

[tomsteve]

Aluminum in general is hard to paint but if the existing paint on it is good, you need to adhere to the paint. Assuming you want the new paint to stick, you'll want to scuff the existing paint which will take longer and more muscle than the painting itself. I know this doesn't sound pleasant but it's really necessary to get a good bond. You'll want to use gray Scotchbrite. The red Scotchbrite is too aggressive and will blow through the thin paint. I'd use a mild dish soap and water mix so you'll be washing the same time you are scuffing. You'll only need 2 or 3 drops of dish soap in a quart spray bottle of water. You'll also want a bucket of water mixed in the same ratio to rinse out the Scotchbrite in to reduce clogging. The soap also acts as a lubricant so it will take less effort to scuff and help reduce the Schotchbrite from clogging. If you use too much soap, it will be hard to rinse off the siding and you'll get adhesion problems. Once scuffed, rinse off the siding real well. I'd also talk to a paint dealer like Sherwin Williams about the right paint and primer if necessary. Rent a sprayer. It's a lot of work, is the color really that bad?

thanks, snipe buuuut im just washing painted siding. the paint that is on it appears to be in good shape from what i see.

[Snipe Hunter]

thanks, snipe buuuut im just washing painted siding. the paint that is on it appears to be in good shape from what i see.

Ok, but you'll still want to scuff it to get a mechanical bond.

[tomsteve]

Ok, but you'll still want to scuff it to get a mechanical bond.

i think im lost. mechanical bond for ????????

[fixtureman]

I use trisodium and a brush then rinse with water

[fixtureman]

Ok, but you'll still want to scuff it to get a mechanical bond.

i think im lost. mechanical bond for ????????

That's what I was thinking he just wants to wash it not paint it scuffing it would ruin the finish.

[blackhat]

  You folks have to cut Snipe a bit of slack. Occasionally his painting fixation takes hold of him for a day or two. I think it’s the solvent exposure.