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-   -   Rust stain on roof (http://www.diychatroom.com/f9/rust-stain-roof-2997/)

krtw 07-09-2006 01:58 AM

Rust stain on roof
 
Does anybody know what I can use to remove a rust stain on an asphalt single roof? I have tried lime-away, this did not work. The rust stain was from a flashing around a chimeney. The stain starts from the top of the roof ridge at the flashing and goes all the way down to the gutter. I repaired the flashing so it won't continue rusting, but really wish I could remove the stain too.

Thanks.

AaronB 07-09-2006 09:10 AM

Change the shingles?

allpraisebob 07-15-2006 06:06 AM

Quote:

Originally Posted by krtw
Does anybody know what I can use to remove a rust stain on an asphalt single roof? I have tried lime-away, this did not work. ...

Oxalic acid. Look for "wood bleach" in the paint department, or "Zud" in the cleaning department. Wet down the shingles in the whole area first then spray the concentrated solution directly onto the rusty areas only. Let soak for about 5 minutes then rinse off with a hose. Oxalic acid is not a particularly strong acid, but it is a strong irritant - getting it on your skin, eyes or in your lungs (breathing the vapors) is very unpleasant.

C-L-R, btw, contains Sulfamic acid which is much better at removing calcium-based depostits but inferior at removing rust. Don't know what is in Lime-Away off the top of my head, but it likely contains sulfamic acid based on its name.

krtw 07-27-2006 03:10 PM

THank you......thank you.......thank you.......thank you.......

OXALIC acid worked wonders. My stain is GONE. What an eye sore that was, I really hated it. THe house is really nice looking, but the big stain on the roof would always catch my attention from day 1 (I bought this house in January).

Thanks again. Praise be to BOB. :thumbup:

allpraisebob 08-11-2006 12:00 PM

Glad I could help! Keep the oxalic acid around in case of rust stains on concrete, wood fences, stucco, etc. It bleaches the heck out of wood, though, so it's not really a good spot treatment for that - great a making a grey, weatherbeaten fence look brand new again, though.

:yes:

mgaa 08-27-2006 03:32 PM

roof stain
 
I have the same rust colored stain on my asphalt shingles I followed your comments and tried Zud powder and it worked great in taking off the stain in a small area. I have 2 questions though:

1) Did you make a solution by mixing powder and water and apply with a garden sprayer and is it safe on shingles?

2) As far as where the stain is coming from, I can't be sure. I have all stainless chimney and aluminum flashing. I think rust is coming from my oil furnace gases. The furnace is 18 years old but it was cleaned and we found no rust. What else could it be?
Thanks

Carol Billups 03-24-2008 09:15 PM

Why don't you try muriatic acid coz' it works by eating away the surface material, thus removing the rust along with some brick or concrete. It does remove rust stains better than oxalic acid, but is very corrosive and toxic to humans, animals and plants. :thumbsup:

mbkerk 09-24-2008 11:50 AM

This thread is 2 years old, but I stumbled on it looking for a fix for this topic using an internet search engine!

I am going to go out and buy some oxalic acid and give this a try... I will post before and after pictures soon!

Thanks you!

Marine0302 06-04-2009 07:33 PM

Roof Leaks
 
Has anyone noticed a roof leak or stones falling off the shingles after using the acid? I don't want to damage my roof. Thank you.

mbkerk 06-04-2009 08:48 PM

Thanks for bumping this thread up "Marine0302"! I had forgotten where I had seen the information I learned here until I got the topic reply notification! (I belong to too many web forums!)

I still have not fixed my problem, however I will be getting to it soon as I have to get back on the roof to replace the chimney cap that I removed to repair a week or so ago. When I do that I am going to do something with the flashing to keep the rust in check, and then clean the rust off the roof!

I have been trying to avoid this as the roof is a 12/12 pitch and I don't like being up there...

I will get before and after shots when I do it, and will post them here as promised soon.

holmes55 06-10-2009 03:45 PM

How did you remove the rust stains from the flashing around the chimney? I am replacing the shingles but would prefer to clean the flashing in order to prevent staining the new shingles.

mbkerk 07-05-2009 09:22 PM

Quote:

Originally Posted by allpraisebob (Post 14352)
Oxalic acid. Look for "wood bleach" in the paint department, or "Zud" in the cleaning department. Wet down the shingles in the whole area first then spray the concentrated solution directly onto the rusty areas only. Let soak for about 5 minutes then rinse off with a hose. Oxalic acid is not a particularly strong acid, but it is a strong irritant - getting it on your skin, eyes or in your lungs (breathing the vapors) is very unpleasant.

C-L-R, btw, contains Sulfamic acid which is much better at removing calcium-based depostits but inferior at removing rust. Don't know what is in Lime-Away off the top of my head, but it likely contains sulfamic acid based on its name.

I am having trouble finding any of these brands in my area. I have looked at Menards and Lowes. Any ideas, or other brands to look for?

RSmall 10-20-2012 12:57 PM

Oxalic acid works for even old rust
 
I know the post "how to remove rust from asphalt shingles" is old, but want to thank those who recommended Oxalic acid. We had our house totally remodeled in 2008 and have been fighting with the contractor over issues ever since. The rust stain on our roof appeared only a couple of months after the job was "completed" (they never tarred over the screws on an exhaust vent) and I finally got fed up.

Oxalic acid cleaned the rust completely even after 4 years. It may actually have helped that the surrounding shingles ("weathered wood" color) have had time to lighten a little from the sun, otherwise the rusted area would have surely turned from a rust streak into a bleached streak. The area had been constantly rusting the entire period because I never replaced or covered over the nails because I expected the roofer would have to come back and replace them. I'm getting to the point where I'd rather just fix the remaining issues (mainly cosmetic) myself because I know this way they will get done right. But I couldn't do it without this forum. Thanks again!

Lems 09-18-2013 05:02 PM

roof rust on asphalt shingles
 
The use of Wood Bleach by Savogran (oxalic Acid) worked wonders on the roof and the stained chimney flashing. Good tip.


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