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spkwms · 10-16-2013, 02:45 PM

We have a fifth wheel with a gelcoat fiberglass exterior.

Below the water heater access door the finish has become dull and discolored due to the tank relief valve discharging water containing lime and other impurities.

Is there a product available that will bring back the original shine without harming the gelcoat finish?

Ramblin · 10-16-2013, 03:04 PM

Many people have had good success with Barkeeper's friend followed by several coats of ZEP. Though I don't know how you're going to feel about the REST of your coach after applying the ZEP. You might want to do the whole thing.

Do a search on ZEP in the search box, and you'll see lots and lots of reading on the topic.

450Donn · 10-16-2013, 03:12 PM

Zep is an interior floor polish, not a wax. It does not contain any form of UV protection. There are dozens of pages all over the internet touting how great this stuff is. Do yourself a big favor, do a lot of research and homework before you leap on board. A similar product is Polyglow and has been used on boats for quite a while. What they don't tell you is that once on if you choose to remove it for what ever reasons it is very difficult to get off so you can start over. It also does nothing for the underlying problem, so before you apply the stuff you first must spend a lot of time getting the base good and clean and also getting the surface back shiny.

Brockx · 10-16-2013, 03:16 PM

You will not regret using ZEP.

Cooperhawk · 10-16-2013, 03:26 PM

Quote:

Originally Posted by 450Donn

before you apply the stuff you first must spend a lot of time getting the base good and clean and also getting the surface back shiny.

Spoken for truth. Any dirt or oxidation that is not removed is sealed into the finish by Zep. You must have it all cleaned off prior to Zepping it.

I finished ours and it looks great.

TDI-Minnie · 10-16-2013, 03:34 PM

These are just hard-water stains, right? Wouldn't a vinegar solution clean it well (like periodic cleaning of a coffee maker)?
Followed by a good wash and wax.

camaraderie · 10-16-2013, 05:27 PM

Try Clorox Cleanup w/ Bleach to remove stains from fiberglass....not generics...Clorox Cleanup spray. For old stains...let it sit a while before wiping.
If that doesn't do it...try some muriatic acid in a 5% solution. Wear gloves!
If the stains don't come off with either or both of those, chances are your gelcoat is porous and penetrated and nothing you do will REMOVE any more of the stains. Trying to buff or polish it out with a cutting agent will just ruin whatever you have left in terms of coating...or require re-painting.
Repainting May be an option for you on a small door. Interlux brushable 2 part Perfection paint gives gel coat like finish for the DIYer and is a lot less expensive than having a pro spray it with 2 part epoxy.
Setting that aside and assuming the stain is pretty well removed...it is now time to polish and protect the surface.
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Just as an added comment to the thread...I have some experience with applying Poliglow to a very oxidized fiberglass boat hull. One thing I can say with confidence is that IF you are applying right...right around the third coat, you will be saying to yourself...OMG...what have I done...this is awful!! Hang in there with it. Follow all instructions to a T from the beginning and try no shortcuts...after about the 5th coat you will be patting yourself on the back for the awesome new look for so little money...and vowing you'll never do it again!! Several years later...you'll find you have to do it all over again as it is starting to look like crap again.
So...it's a great temporary fix that takes a lot of time and elbow grease but saves a bunch of money vs. a re-paint and looks great for a couple of years. Last resort...to restore a badly damaged finish. Try other stuff first!! IMHO.