Fiberglass pop top: Drilled hole repairs recommendations

[MrBuelterman]

My fiberglass pop top has a few drilled holes in it from previous owners that I would like to repair/seal up. I figured I'd ask the group on the best way to repair them before going ahead with my own solution.

The way I was thinking about tackling the repair is to
1. Clean out the holes a bit with a rat tail file to give the filling agent a good clean surface to grab on to.
2. Use a few layers (5 to 10 if need be) of masking tape on the outside of the pop top to build up a solid backing for each hole. I may make a few pin holes in the tape backing to allow air to escape. One worry I have is that the filler will bond to the tape and I'll have to deal with cleaning/sanding the tape off of the hole. Maybe some parchment paper or cling wrap should be the first layer of backing? What will curing fiberglass not stick to?
3.Fill the hole from the backside of the pop top.

I'm hoping that by sealing the front of the hole and filling from the back, I will get a nice clean finish without any sanding.

The main question I have is what kind of filler should I use? I'm looking for a squeezy tube of fiberglass resin with chopped short strand fibers in it, in white. Are there any products out there designed to make this kind of job as easy as possible. I can make a batch up myself but it would be much easier if I didn't have to.

Please comment if you have a better method of dealing with the repair.
Thanks

[greenraVR6]

They have cheap fiberglass repair kits at west marine, I'd try one of those
_________________
'88 vanagon*****'91 gti 1.8t*****'04 r32*****'11 suburban z71

[Dampcamper]

West Marine's or most any automotive FLAPS fiberglass repair kit. If you want a really secure patch, use a layer or two of thin glass cloth resined over the rear then fill the front (Bondo, baby!) and sand smooth. You'll have to scuff up any surface you want the glass to stick to. I don't know what you plan on finishing it with or how particular you are about how smooth it's going to look? This determines how much sanding and filling you will do. Using tape as a mold will get you close to flat but maybe not perfect.
If you're in a big hurry and just want to "putty" the hole (which may fall out when you hit a bump?), epoxy will give better adhesion but is a bear to sand after it cures. Usually it is harder than the surrounding gelcoat so you end up with a high spot and a ring sanded away around it.
You can wax the area around the patch and that will reduce the adhesion of any stray resin. Be very careful not to get wax anywhere you want the resin to stick.
You can add white pigment to resin, to a point, but this will give a translucent "whiteness" to it, like skim milk. If you want an opaque white you'll want to dab some enamel over the patch or gelcoat it. Which is where the marine-type kits may help.

[WestyJP]

Here is a good guide on the subject with explanations for some the different techniques that you can use to fill a hole in fiberglass:

http://www.westsystem.com/ss/repairing-machined-holes-in-fiberglass/

I've done a good bit of fiberglass work/repair and depending on the finish and longevity of repair you are going for you will likely need to do a more involved repair as described above. Many fillers, especially polyester resin based will probably shrink as they cure/age and could separate if you simply plug the hole with them. The tapered sanding/enlarging of the hole and filling of a larger area will prevent these types of problems and give you better adhesion and a repair that is more likely to be stable as it cures and heat cycles etc.

Another set of factors to consider revolve around how you plan to finish the repair and with what materials. There are a few materials that will give you a good structural repair and you also have a few options with finish coatings. You'll need an exterior coating in most cases to protect the filler from uv. Gel coat will only go over polyester repairs where other coatings and paints will be compatible with epoxy based fillers.

It doesn't have to be too complicated but a little reading and selection of the right process/materials will go a long way towards making this a one-time repair.

Jonathan

[Syncro Jael]

Not sure if this is the way you would like to go but you could find a plastic automotive plug and paint it white then just silicone and plug the hole. Easy and shouldn't look bad.

_________________
1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat)

[morymob]

[j_dirge]

[Howesight]

A super-easy and cheap permanent fix is to just use gel coat. If the holes are small (say, 4 mm or less in diameter), just take one of the free sample cards of formica they had out at Home Depot, wax it like crazy with normal car wax (say, 5 coats), and tape it over the hole on the outside of the top. This becomes the back up for the gel coat you apply with a small brush from inside the top. Mix up some gel coat, apply once, again on hardening, and again until the hole is filled.

You can even tint it in advance to match the (faded?) white on your pop-top. If you are going to paint over the hole repair anyway, then just use epoxy instead since it will work with just one application.

On the other hand, if the holes are large, you should use resin and fibreglass matt, but you still should use gel coat on the exterior portion to protect the fibreglass under it from weather. If you do not back up the gel coat with a mold, and you apply the gel coat last, then you have to use "air drier" - - a chemical all fibreglass distributors will sell. Without this chemical, the gel-coat remains sticky, even though it hardens. This can trap flies, gnats, Seattle fans and the like.
_________________
'86 Syncro Westy SVX