House mix for painted home

Just did some gutters on a home that was painted. I didn’t have issues with over spray but was thinking what would the standard house mix do to paint. Any stories out there about stripping paint or sh bleaching the color?

One third SH, two thirds water. Downstream. Don’t wash red, blue, brown or green painted siding


Don’t wash them at all? Or do a SH test somewhere first? I’ve heard about certain paints color changing, but is it something you can test for, or will you come back the next day and have a new color home?

I’ve seen to many turn to gamble. There isn’t really room on my schedule to go do a test and cone back another day.

Would this be one of those colors?20180503_165531|374x500

My picture didn’t upload. Standby

No what I meant was… can I do a quick test then wash? Or is it some type of delayed color change where a test and wash 10-20mim later would do no good?

Brodie had a good post about a test spot before. He said a normal spray bottle with house wash mix in it would be sufficient. Test on an inconspicuous spot, let dwell and rinse with a normal hose. See what happens.

We use a zep spray bottle filled with a little stronger mix than what I’d spray on the house. I prefer to spray it behind the AC or a bush.

A pitcher to fill at the tap and rinse it off 10 minutes later. If it doesn’t react right away you’re likely in the clear. Never had a problem with the exception of hunter green garage doors which my painter repainted for $50.

Blue houses though… they always dry strange and leave you in a state of panic until it’s fully dry and fine.


I agree with @Innocentbystander about those colors. I did a house wash on a brown house, stucco. All of those houses in that area used Sherwin Williams paint and above the garage, you can see where they used the roller, rather than the sprayer and it was a shade lighter. That was with a fairly weak mix, too.

Had this happen to me Friday. It look like hot runs down the house until it dried. I was preparing myself for the worst.

Is it hardiplank? Did you wash this one?

Yes it is hardiplank. I haven’t washed it yet. Bidding on it, but remembered that some colors don’t do well with bleach. I was gona test spot per Brodie

Looks like 90% of the houses around here, southern coastal DE.

How does the HW react to it? Just normal washing?

I washed a painted dark blue house on Saturday. I did a test spot and made the customer inspect the test area and give me approval before finishing the job. They were very happy with the results! The house wasn’t even dirty! Just had about 6 spots where mold had grown and it was freaking them out.