Tips for working with fiberglass

[campinmom]

Hello all!

Just wondering if anyone has any tips for working with fiberglass. I've finished packing the bearings on both wheels (boy was THAT a learning experience :book: ), and I'll finish painting the last wheel tomorrow. Then its onto that roof. I went to Walmart and bought a fiberglass "kit" from a company called "Bondo" (I think, don't hold me to that one). I have a waterproofing type paint that I'll use when I'm all finished, so I didn't go the extra step to buy the marine version of the fiberglass patch stuff.  I thought if its good enough to use on the body of a car, it should be ok on the camper top. I've already used a wire brush to remove any old caulk or other material the old owners might have used there.

Now, just looking at the outside of the box, they make it sound like you just mix it up and slap it on. I *know* there's got to be more to it then that! :rolleyes: So, any tips or hints you can share, I'd appreciate it!

As always, I'm very grateful to you all for the support and help you've provided already! :W

[mike4947]

Just remember Bondo is auto body FILLER not designed for bridging gaps or bonding two pieces together. It's a polyester resin putty type compound made to fill surface dents to recreate a smooth surfce for painting.

Gaps or large cracks usually require fiberglass cloth and liquid resin reinforcment to prevent the crack from opening up rather than a putty type filler compound.
 
If it were me I'd do a Google search on Repairing fiberglass before starting. If you have a WEST Marine or U.S. Boat store near you they have repair manuals fr about $3-$4 each for repairing fiberglass in differnet applicantions.

[aw738]

Campinmom may very well have a fiberglass repair kit. Bondo does make a kit that contains a piece of fiberglass mat, resin, catalist(hardener) and mixing tray. It is in a blue box. If that is not enough to make the repair than it is available in gallon sizes along with bigger pieces of the mat. This might be overkill though. Can I ask if the crack that you are filling is flexable or are the parts rigid? If they are flexable then the fiberglass kit might not work.

[angelsmom10]

Here's a link to pics Erin posted in another topic and it'll show the areas she has to fix.  Maybe this will help with someone's expert opinions.
 
 
http://share.shutterfly.com/action/share/view?i=EeENmzZizZNnPQ&open=1&sm=0&sl=0

[campinmom]

Thanks! Yes, I did purchase the fiberglass repair kit. It has all the things in it that aw738 mentioned. Thanks Angelsmom for posting that link. I should have thought of that!

I'm repairing the rather large break on the top of the camper shown in the pictures. The top of the camper is made of a plastic/fiberglass material. Its definately solid and not flexible

It is ok to put more than one layer of that fiberglass cloth (after it's dry) if I think I need it? I read in the package insert about the body filler Mike4947 mentioned. Should I put that over top of the fiberglass "patch" after I've sanded it smooth, or won't I need it?

Thanks again for all your help!

[mike4947]

You can put on multiple layers as long as the previous layer is dry and hard. The can usually has "recoat" or cure times on it for use between layers.

The filler is only needed if your finished surface isn't smooth. A little extra resin or an extra coat on the outside gives you some sanding room rather than buy a seperate product. The filler stuff does sand easier because of the filler in it, versus solid resin.
 
One "trick" is to put the glass cloth and resin on the inside if you can get to it for strength and then fill the resulting crack with filler. That way you don't have the overlap hump of the cloth and resin on either side of the opening. Which is a bear to feather out.
 
Many times trying to get  the surface smooth I ended up sanding back into the cloth in the resin to the point the patch didn't have much left to hold on with.

[Firefyter-Emt]

Ok, your biggest thing is that fiberglass will not bond to gell coat. You will have to gring the area to get down to the fiberglass itself. (the gel coat is that smooth skim coat on top of the glass.) You will also want to "V" out the crack and make sure that if you have any "dirty fiberglass" in the crack that it is ground out as well. Take some of the glass matting and mix cut strands of the matt into your first couple of layers of glass. (it will make it stronger) I would also drill a 1/4" hole at the ends of the crack to keep it from spreading. You can build it up in multibale coats, but you have to sand / grind inbetween the coats. (get ALL the shiny spots sanded!) You will need to do this in a few steps, as the resin will harden very fast. But many many acid brushes to smooth it out and a few bondo spreaders. Poly-resin filler ("Bondo") can be used to smooth it out, but a product called "Vette adhesive" is best used. It is a compuond like bondo but made to bond & use as a body filler on fiberglass and "SMC" ( Sheet Moulded Compound ~ What Corvettes & all "fiberglass cars" are really made of)
 
By best tip, wear a resporator while working with it, even while not sanding! and apply a lot of hand lotion all over your arms,head, and neck (all exposed skin) it will keep the glass out of your pores and keep the itch down.
 
Just ask if you need more info~!
 
Lee

[Firefyter-Emt]

BTW.. I just looked at your photos, and that looks more like ABS plastic to me.. I do not think the fiberglass will hold well to that roof.  You may want to think about bracing the back of it with metal & pop-rivets. The fiberglass will not hold that well. You can "cheat it" by drilling a lot of holes thru the top around the crack & repaired areas to give it a "grip" thru the roof. I would highly recomend glassing the backside to bond in with the hole "plugs"