Fiberglass sidewall Yellowing

[RetiredMil]

I have a 1995 Four Winds motorhome which has been garaged when not in use. The motorhome now has a yellow tint to the beige color. I would like to remove it but I don't want to damage the fiberglass. Fabwel Composites of Goshen, Indiana (the manufacturer of the sidewalls) recommends just using mild soapy solution with a soft cloth or sponge to wash the unit regularly. After washing Polish sidewalls as recommended by wax manufacturer. Caution do not use abrasive cleaners or scuff pads. If you use a buffer to polish your unit, be sure to use a clean buffer pad. Keep the buffer moving constantly and use only the minimal amount of pressure to buff sidewalls. My question is this. What is the best product to use with a air buffer for the larger areas and by hand in the small areas? I find that 3M Finesse-It II Finishing Material does well on the end caps. I use many of your products but they are hard to find in South Dakota.

[Michael Stoops]

Re: Fiberglass sidewall Yellowing

Ah, the sometime ambiguity of manufacturers care instructions.

Using a buffer and a buffing pad is an abrasive process, no way around it, so don't get too caught up in the admonition to not use any sort of abrasive cleaners or scuff pads. We're willing to bet they're referring to the unfortunately all too common use of things like Comet or Scotch-Brite pads that people tend to reach for when things get bad! And then they just get worse.

A product designed for use on the gel coat finish is going to have some level of abrasive in it, depending on it's intended use. If that use is to remove oxidation (the yellowing you're referring to) then the product is going to have some sort of abrasive in it in order to accomplish this task. These products, like M49 Oxidation Remove or M67 One Step Compound, will have varying degrees of abrasives in them and selection is based on severity of oxidation or other defects, and method of application.

So, if the amount of oxidation on your rig is minimal, M49 Oxidation Remover would be the product of choice, whether working by hand or with a buffer of some sort. If you can't source our Marine/RV line products locally (RV and Marine supply stores are usually the best sources as typical auto parts stores almost never stock them) then you might try Ultimate Compound from our consumer automotive line. This should be readily available through most larger auto parts stores and even WalMart. It's still fairly aggressive so it should be up to the challenge of gel coat, which is typically much harder than automotive paint. It should be up to the challenge, provided the gel isn't badly dried out and heavily oxidized.

Application should be confined to fairly small areas at a time, meaning no more than about 2' x 2' at a time. Work the product against the surface for a few minutes or until just a thin film remains, but is still wet, then wipe off before it dries. Allowing it to dry serves no benefit and just makes it hard to remove. Keep in mind, too, that this is not a wax so you will need to apply a wax once you've completed use of Ultimate Compound or any other cleaner.

[THE BIG BUFFER]

Re: Fiberglass sidewall Yellowing

Keep in mind, too, that this is not a wax so you will need to apply a wax once you've completed use of Ultimate Compound or any other cleaner.

I am also about to polish my first Motorhome( I've been polishing cars for about 12 years) that is oxidized( white/chocky looking). I have #49 and #50. Would I still need a polish after these are used? Totally unfamilier with gelcoats. Thanks for the info.

[Michael Stoops]

Re: Fiberglass sidewall Yellowing

I am also about to polish my first Motorhome( I've been polishing cars for about 12 years) that is oxidized( white/chocky looking). I have #49 and #50. Would I still need a polish after these are used? Totally unfamilier with gelcoats. Thanks for the info.

If you were to use a polish in your process, and it's an optional step on gel coat just as it is on paint, then you would do so between the M49 Oxidation Remover and M50 Cleaner Wax. These two steps can be likened to using Ultimate Compound and ColorX on paint except, of course, that M49 and M50 are designed specifically for gel coat. If you do choose to polish in between these two steps, keep in mind that M50 Cleaner Wax will likely remove most of the polish you've applied, so M63 Flagship Premium Marine Wax (not M61 Flagship Cleaner Wax!) or M56 Pure Wax would be a better choice to follow a polish.

[THE BIG BUFFER]

Re: Fiberglass sidewall Yellowing

If you were to use a polish in your process, and it's an optional step on gel coat just as it is on paint, then you would do so between the M49 Oxidation Remover and M50 Cleaner Wax. These two steps can be likened to using Ultimate Compound and ColorX on paint except, of course, that M49 and M50 are designed specifically for gel coat. If you do choose to polish in between these two steps, keep in mind that M50 Cleaner Wax will likely remove most of the polish you've applied, so M63 Flagship Premium Marine Wax (not M61 Flagship Cleaner Wax!) or M56 Pure Wax would be a better choice to follow a polish.

Thank you.