Ceiling Discoloration Marks

[Festus2]

We have a 2008 Cougar 5th wheel and have recently noticed a number of small and barely noticeable yellowish/brownish discoloration at points where the interior white textured ceiling panels have been fastened to the overhead rafters/joists.
I am sure that these ceiling panels have been stapled and some kind of white filler has been applied to fill in and hide the staples.
These stain marks are in a direct line and spaced fairly evenly apart - running across the ceiling from side to side. The more obvious ones are in the kitchen area but other ones are also beginning to show.
It would seem that the compound or filler that was used to hide the staples is reacting with the metal staple and producing some kind of chemical reaction which is resulting in the filler turning a light yellow/brown color. I am certain and it was confirmed by the technician that it is not a leak problem.
Upon checking with an Keystone RV dealer, I was told that this is not an uncommon problem and the stain marks might be removed by lightly rubbing it with a damp cloth and a mild detergent or cleaner.
I was also informed that the filler used becomes discolored by cooking "smoke", dust, and other airborne particles.
:confused: I am wondering if anyone else has experienced this and if so, what they have done to solve this problem. The one year warranty is, of course, expired. I havent yet contacted Keystone to see if they can offer any suggestions.
Any comments? Suggestions?

[Flyguy]

I have the same thing in a few spots but they are so small that I'm really not concerned with them, I expect that I'll see more of them as the trailer ages. I was told that the best thing to use for cleaning the trailer outside, and especially the rubber roof is Borax powder (20 Mule Team) in lukewarm water, I might try some of this on those spots.

[HermitKrab]

I also have some discoloration in various areas of the ceiling as you described.
I was worried they might indicate a moisture problem, but glad to see that is not the case.

[Umpie007]

i have a 01 278efs fifth wheel and have the same thing. i keep thinking it's flypoop when i look up.....until i look closer.. i don't know what it is or how tho fix it

[Festus2]

Umpie
The discolouration does not seem to be spreading or enlarging. I have tried various cleaning solutions - including Borax but the stain seems to be embedded right through. I am almost certain that these marks are caused by a reaction between the staple and the fill used to cover the staple marks. Also, I am also certain that they are not caused by leaks. It must be a water-based fill and the discolouration is rust caused by the reaction between the fill and the staple.

I have tried using Kilz in a small test area and it seems to have made a very slight improvement. The marks are barely visible. I am less bothered by them now than I was when I first noticed them. If I ignore them long enough, they may eventually go away.

[hankpage]

Mr Clean Magic Eraser removes them with just a gentle rub. I see why they call it magic. :eek:

[Festus2]

Hank
I will give Mr. Clean Magic Eraser a try. Does he come with the bottle and apply a "gentle rub" or do I have to do that?

[hankpage]

Actually I think he is too old for house calls, so you'll have to rub it yourself. It is a small white sponge ... just wet it and rub lightly.

[cpaulsen]

Had the same thing in our Couger. I used a rag wet with Awesome Orange and the marks went away.

[sbebenelli]

The Mr. Clean Magic Eraser works great on all sorts of things. I recommend having one around the house. You'll be amazed at what it can be used on.