Need confidence boost - rust removal on vinyl

RSfront RS%20Front
I’ll will be washing a 10K SF commercial building, mostly vinyl. Building has 2 rust stains on 2nd floor, one in the front-serious eye sore, 2nd is in the rear of building. The cause of stain has been fixed, from a few years ago. I’m confident of building wash, I’d greatly appreciate any suggestions the experienced washers are willing to share for the rust stains.

I’ve only used F9 twice on concrete rust stains, 2 foot areas, both successfully removed. I am new to PW’ing started in May this year, LLC & insured. I’m a thankful & avid reader here & a bookmarking abuser.

I have almost a gallon of F9, thinking 1:2 ratio, multi application, hoping I have enough. Any “guestimate” of how many applications? I’m trying to determine pricing on time & materials.

Also, If I may, I’d like to describe my approach here before I move forward with the job just to be sure I’m moving in the right direction?
Starting in the back, 2nd floor, experiment & get a better feel for the vinyl application in an area hardly even seen. Afterwards, I’ll move to the front of building. The rust is directly over the center of building, a horrible sight and I will be ecstatic when I remove the stain for them. <— can-do attitude!
From what I’ve read, wet/mist area 1st, apply 1:2 F9 with pump sprayer, I have a brush if needed, assuring surface never dries. I’m thinking 1:2 1st & 2nd application, 1:1 for additional applications?
I’m also washing building. Should I consider a splash of F9 in my wash for front of building to attempt to blend in the area of stain? (keeping away from spraying windows)

Here is where I start to overthink… I would rather overthink then screw it up! Both rust spots are in the corner of windows which may be a concern for window splash. In addition, asphalt roof shingles and gutters are under the windows. Do I have an issue with F9 running off on shingles? on gutters? I will lightly spray with water as I’m working on stain.

As mentioned, any feedback, recommendations etc appreciated. Thank you for your time in advance, Anne

Check this thread out of a job me and racer did.


I seen @squidskc had good results removing rust off vynal with oxalic as well. Its way cheaper.


Wow! Just what i needed! Looking at your pics make me breathe a lil better :sweat_smile: Excellent work! Thank you!
Reading up on your post now, GREATLY appreciated!

Thanks @grizz, I do have a great post
saved from @squidskc about oxalic. I entertained using it for 1st application or two.

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Oxalic works for me 90% of the time, but F9 BARC is unbelievable. I have gone thru 16 gallons this summer and have 8 more on the way. It’s expensive, $155 for 4 gallons, but WOW it’s worth it!!


I’d just try oxalic first. It’s normally enough on vinyl and no need for F9 Barc. It’s nice to have as a backup though. Just spray oxalic on using a pump up and watch the rust disappear. It might take a handful of applications. Just do one right after another. I wouldn’t brush at all unless absolutely necessary. If you disturb any oxidation you’ll be scrubbing the whole side of the house. Rust cleans up really easy on vinyl.


Woe! Thanks for heads up on scrubbing out oxidation! I do think I’ll try oxalic first with F9 as back up. Appreciate your input.

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Listen to these dudes and it will clean up nicely. No need to stress.


Oxalic for vinyl and paint. F9 for anything porous.


If I’m reading this correctly, never ever mix bleach and acid…ever.


Ditto. I have yet to have F9 clean where OA failed. SO, I follow @squidskc 's advice and tell the customer that although all of the stain often disappears, the last 10% is at the vagary of the gods. That way you’re off the hook if you can’t get it all, and a hero (and an ovious favorite of Zeus) if it all goes away. :wink:

One caveat: if you fail to get to the bottom of the stain on that siding it will return after a good rain because all you did was bleach out the top layer. I brush lightly while using the oxalic to get ALL of the rustr stain gone.


Oxalic will not remove rust stains, actually converts one molecule & the stain disappears but the rust is still present waiting for the PH to change & reconvert the molecule & the stain is back. Hydrochloric & phosphoric will actually burn the rust off or put it into solution so it can be rinsed away.

Ox acid does convert rust into a ion that can be washed away that’s why it works.

Thanks @MrSparkleVA. I did include the questionable 10% in the estimate, although not written quite as eloquently as you wrote :smiley:
Duly noted on the bottom of vinyl. Luckily brushing bottom will not be visible from 2nd floor, should I disturb any oxidation as @marinegrunt so kindly reminded me.

NICE SAVE my friend !!! We need to get you a lil golf cart with a siren on top,a cb radio with microphone and a PWRA badge and a ticket book. :loud_sound::mega::postal_horn::oncoming_police_car::police_car:
Crap… Forgot the body camera, here ya go bubby. :movie_camera: :camera: :video_camera:


no that is incorrect, spray a well water stain with oxalic then rinse after its dry & stain is gone spray some SH on it & tell me if the rust stain returns I bet you it will & I have been at this since 1991

Yes you are correct sh will not remove it but ox acid will. I

Here you go rust treated with ox acid then house washed with sh no stains have ever come back. Sh does not activate iron. Oh and the rails are vynil but the post are painted. The only way the rust would come back is if you are crazy enough to wash the house with the same well water that caused the stain in the first place

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Lol. Give good advice or no advice

I didn’t say SH would remove it ?? I said SH is an alkaline that will alter the PH of OX [an acid] & the rust returns. Ox alone will not remove the ferrous iron on the surface, it changes one component of the iron just like SH turns mildew white it will not completely remove the remains from the surface. Ask chem girl