Fiberglass Pop Top Restoration
by John Anderson
Camper pop tops are a nightmare to do right. You can try scrubbing with a phosphate cleaner, then give it a rubberized white RV roof treatment. To do one right is to re gel coat yourself with a professional polyester surfacing primer or have it done professionally. The thick RV stuff will rebuild gloss over the worn fiberglass and you can do it.
A real good thing to do first: get yourself some sprayable polyester filler and put it down on the sanded glass (this is basically thin spray gelcoat). I've used a brand called Z-chrome (about $50/gallon here) but there is a more common brand that is a bit pricer (about $20/qt). I would leave a lot of tooth for this stuff, sand to about 180 then lay down a couple nice heavy wet coats. It goes on real nice and can actually fill the big scratches. You spray it as is out of the can, adding only catalyst. This will basically restore the origional gell-coat in a cheap manner. It can then be sanded wet to take off the orange peel (which is not very much) and topcoated to your desire.
Regular epoxy primer, even good stuff like DP90, isn't going to cover heavy enough to bury the exposed glass you will be hitting into--but this will. I swear by it on all things (usually used on metal right after a good epoxy primer). It is a totally, 100% shrink free primer surfacer, wonderful to work, and yields beautiful results. I tried it first time about a year ago on the '90. It is everything it claims and more. But use an old gun and clean it ASAP with acetone. For a full paint job this stuff is miraculous, allows you to take out all kinds of minor surface imperfections after you've gone to bare metal or if you have just done rough bondo work and want something to fill all the pinholes.
"What sort of a gun are you using to spray this stuff? Just a regular suction gun or some sort of HVLP or pressure pot system?"
I'm using my oldest, ugliest primer siphon gun, but I drilled out the fluid tip to a fairly large size (hey you try to find needles and tips for a 10 year old taiwan gun). I basically drilled it as big as it looked like I could. It puts the taper of the needle much farther out the tip--works very nicely. The stuff I used (I think Z-Chrome Rust Defender is its name) is about 1.5-2 times as thick looking as properly mixed acryllic enamel. It does not get thinned either, just goes straight on. It also goes on well even with the siphon gun without much overspray or orange peel. I must have lucked out on the modified tip orfice size. The stuff is so heavy it just wants to go on the desired panel, plus it does not dry quickly at all so overspray settles on and sinks in. It takes a good time for the surface to fully dry. I don't recall exactly but a good couple (3+) of hours. Mine is basically just polyester resin, thinned with styrene I'd suppose, with a yellow pigment so you can see where you've been. In thinking about it again, I think I'd do a full pop-top to about 180-220 dry before I sprayed, experimenting a little to make sure the stuff will cover. But I'm fairly sure I've gone straight from 180 to spray this, to 240 and 320 final sanding before using a heavier topcoat.
As another general gun plug, I'm still 1000%
satisfied with my gravity cup Sharpe HVLP. It has to be one of the
best $150-$200 guns on the market. The HVLP actually works (perhaps
not so well as a full turbine system). I like the gravity cup and
the balance of the gun a lot, save for the fact the cup is
small.
