Stumped

[csoldier]

Hi. I live in N.O., La. where it is very hot and humid. I have had a few situations in which we pressure washed houses with painted wood surfaces to remove mildew and the mildew returned in a very short period of time. We use bleach and liquid Tide applied with the x-jet nozzle. At the time of the cleaning, the surfaces looked great. However, in a period of as short as 3 weeks, the mildew returned and sometimes appeared to be heavier. Any insight as to what I can do or is this something that is going to keep happening. I want to sound knowledgeable to my customers, and they also pay good money for our services. Thanks for the help.
Mark

 

[Harold Brantley]

Mark, I am close to you with the same weather conditions. I live in the Mobile, AL area. Sorry for the delay but I've been out of pocket for about two weeks.

My response to your post would be to make sure your house wash solution is concentrated enough to do the work. If it is too weak, you have to use to much pressure (mechanical cleaning) to make the surface look clean and the mildew may still be on the surface though not visible. Then it will take very little time for the mildew to grow and become visible again. Also the bleach needs dwell time to kill the mildew, so make sure your detergent gives enough suds to hold the bleach in place for a few minutes. If the mildew is heavy, wait a few minutes and reapply your chemical solution. Don't rush the dwell time, but don't let the solution dry on the surface.

What concentration of bleach are you using and what percentage pickup does your chemical injector have? Do you see some suds on the surface when you spray your chemical solution? Are you allowing enough dwell time?