black spots on fiberglass roof

RKL · 10-18-2012, 04:41 PM

I have a lot of small black spots on my roof that do not wash off. I assume they are mildew spots...What is the best way to remove them and what are you using to protect the roof.....somewhere I read that using Mop and Glow was a good product to use and it kept the roof protected and clean..Any help is appreciated....RKL

Shellback1 · 10-18-2012, 04:59 PM

Quote:

Originally Posted by RKL

I have a lot of small black spots on my roof that do not wash off. I assume they are mildew spots...What is the best way to remove them and what are you using to protect the roof.....somewhere I read that using Mop and Glow was a good product to use and it kept the roof protected and clean..Any help is appreciated....RKL

Bar Tenders Friend, in home depot or lowes.

FIRE UP · 10-18-2012, 06:14 PM

RKL,
Before you go using and floor treatments, and or any cleansers, try just about any automotive wax and or auto paint polishing compound or even better, "Gel Gloss" which is sold in quart sizes and in multiple extablishments like RV supplies and sometimes Home Depot etc. I'm pretty sure you're correct in assuming it's a mold or mildew of some sort. I had several zillion black spots on mine when I decided to do some serious clean up, up there.

I went the semi-hard-easy way. I say that because I used a buffer with a wool pad and a paint polishing compound. It removed all the black spots and this is now what it looks like. In some of the pics, it's so shiny and protected now that you see the ribbing/tubing used for the cover of the motor home.
Scott

Keith K · 10-18-2012, 06:23 PM

I had the same problem and just finished mine. After trying rubbing compound and fiberglass cleaner without much success, I found that using Soft Scrub Commercial cleanser (bought it a Lowe's) and a green scrubbing pad on my buffer cut through the oxidized layer and the black spot without much effort. It left the fiberglass completely white and smooth. The hardest part was mopping up with a towel and bucket. Afterward, I used Mop N' Glow; probably not the best protection, but it's easy to apply and seem to last as long as anything else.

Qwert66 · 10-18-2012, 06:31 PM

For small spots we have had success with "Mr clean" white magic eraser which also removes black marks from white powder coated aluminum. To protect some use 303 Aerospace Protectant (Armorall on Steroids without the silicone) Just dont walk roof in socks and then go inside .without removing socks unless you want a slip & slide floor like the oven cleaners of old. 303 is basically a uv protectant.

RKL · 10-19-2012, 03:41 PM

thanks for the responses. I am going to try the paint polishing compound and wool buffing pad on my orbital buffer...Will let you know how it turns out.....RKL

Clay L · 10-20-2012, 08:25 AM

It is possible that the spots are tree sap. You might try cleaning a few spots with isopropyl alcohol and see it removes them.

FIRE UP · 10-20-2012, 06:22 PM

RKL,
When you say "orbital buffer", are you talking about those kind that have a random orbit and very slow rotation? If so, that's not the kind I used. The one I have is this one:

It has the speed to polish oxidised paint, fiberglass and more.

The random/orbital "polisher" is primarily to remove wax, after it's been applied on surfaces.

Home > Boating > Maintenance > Cleaner Applicators & Tools

Just thought I'd throw this at ya.
Scott

winnie32v · 10-26-2012, 03:24 AM

I had a lot of random 'black spots' on my fiberglass roof and removed them with 'Super Clean' (...available at WalMart) and a medium bristle brush. Non-abrasive and works wonders on a fiberglass roof. I used a paste wax...by hand....and the roof really shined when I was done.
I may have to try one of those liquid applications next year.

StewNTexas · 10-26-2012, 07:51 AM

I tried a number of products, quite a few different brushes and chemicals to clean spots off the roof of a recently purchased new-to-me motorhome.

The best thing was the Mr. Clean Magic Eraser as mentioned earlier in this thread.

This is not my first rubber roof, but this product left the roof looking like it had been replaced with new covering. I am now a firm believer in this product.

FIRE UP · 10-26-2012, 10:12 AM

Quote:

Originally Posted by StewNTexas

I tried a number of products, quite a few different brushes and chemicals to clean spots off the roof of a recently purchased new-to-me motorhome.

The best thing was the Mr. Clean Magic Eraser as mentioned earlier in this thread.

This is not my first rubber roof, but this product left the roof looking like it had been replaced with new covering. I am now a firm believer in this product.

StewNTexas,
Just wondering, in the quote above, you state:"This is not my FIRST RUBBER ROOF, but this product ......

IF so, are you saying the roof you're working on or, have now is a RUBBER ROOF? If so, we're all talking about fiberglass roofs on this particular post/thread. No biggie, just making sure we're all on the same page.
Scott

StewNTexas · 10-30-2012, 01:38 PM

Reply to Fire Up,

You are correct sir.

I was so happy with the results I got on my RUBBER roof that I got excited and read what I wanted to, not what it really said.

Please excuse me for mis-posting.

FIRE UP · 10-30-2012, 02:03 PM

Quote:

Originally Posted by StewNTexas

Reply to Fire Up,

You are correct sir.

I was so happy with the results I got on my RUBBER roof that I got excited and read what I wanted to, not what it really said.

Please excuse me for mis-posting.

StweNTexas,
Not a problem Sir. Glad you got your Rubber roof in the shape you like it. I messed with a Rubber roof on our Bounder for 7 years. I always kept it clean and nice. I'd scrub it with soap and water and a fairly decent brush. When done, it was always nice. I finally got tired of looking at the big, black, blotchy spots, (Roof was mostly black after 7 years that we owned it) and, we didn't have a cover for it so, it was always out in the sun. I gave it a deep, thourough cleaning and prep and coated it with Dicor coating, two coats. Looked fantastic and no more streaks etc.
Scott

lenkerb · 01-03-2013, 10:46 AM

Cleaned my roof for the first time since purchasing last February. The roof is fiberglass so I got some Awesome and a hand scrubber, started at the front and hosed as I went.. it wasn't too easy. Some of the spots were like cement...and the dicor around the vents and air conditioner just didn't look like the scrubbing was working. So I got the Mr Clean Magic Eraser and it took everything off and it was easier than using the spray bottle and scrub brush!
I have to redo my seams with eternal bond and and go over the original dicor...then I am going to put rain gutter over the overhangs to prevent the streaking....good thing we are in Florida where the weather is cooperating!!

Deucenut · 01-08-2013, 08:45 PM

Quote:

Originally Posted by lenkerb

Cleaned my roof for the first time since purchasing last February. The roof is fiberglass so I got some Awesome and a hand scrubber, started at the front and hosed as I went.. it wasn't too easy. Some of the spots were like cement...and the dicor around the vents and air conditioner just didn't look like the scrubbing was working. So I got the Mr Clean Magic Eraser and it took everything off and it was easier than using the spray bottle and scrub brush!
I have to redo my seams with eternal bond and and go over the original dicor...then I am going to put rain gutter over the overhangs to prevent the streaking....good thing we are in Florida where the weather is cooperating!!

Be careful with the magic eraser. That thing is basically a fine sandpaper and if you scrub too hard, you might actually go through the gel coat. Probably not on the first time, but if you use it repeatedly, you might see a problem.