Teardrops n Tiny Travel Trailers

Just wondering what others are using to fill all the holes etc before they use the Epoxy Resin? I was told by someone to just use automotive bondo that you find at an Autoparts store? I will be applying the Epoxy resin over the top and then multiple layers of latex paint over the top of the epoxy. Would the bondo work just fine? I did countersink all my exterior screw heads so they will need to be filled.. And there were a few here and there that may not have hit were I wanted and backed them out so now there is a hole there. We won't talk about that though... haha

I used epoxy mixed with micro balloons

I used Smith's Fill-It. It is epoxy based and totally compatible with most epoxy systems. Bondo is not compatible with epoxy. I used this to fill screw holes and all the other little blemishes in my plywood skins before epoxy and paint. If I recall, I bought it at a local marine supply store, but you can probably find it online by Googling the name.



You might want to check on the compatibility (and wearability) of latex paint also. It probably depends on your primer. I used Zinsser oil based primer and Rustoleum enamel for my paint system. Put it on with 4" foam roller and it turned out looking like a spray job. The secret was to dilute the final coat with 25% mineral spirits.

'Conventional wisdom' says polyester and epoxy resin systems aren't compatible, but 'conventional wisdom' also says you can catch a cold by being cold or that carrots are good for your eyesight. Sometimes things get repeated so often that become a truth unto themselves.

Fortunately for us, they are indeed compatible.
The problem with laying poly over epoxy comes when the amine blush (which isn't compatible) is not adequately removed from the surface of the epoxy and contaminates the bond. Fortunately, that blush is water-soluble and easy to remove...but we need to be thorough about it.
Going the other way, epoxies have long been used to repair boats laid up with polyester based resins. A barrier coat of epoxy based paint (like InterProtect 2000E) is applied over the (vinylester-based) gelcoat of virtually all new boats below the waterline before antifouling is applied...but again, the hull has to be thoroughly cleaned of any residual wax left over from the mold. Epoxy can encapsulate and form a mechanical bond with almost any substrate except soft, waxy plastics.

One of epoxy's virtues is that it is friendly to so many different materials. That's why it can be mixed with many different additives. Milled fibers (Cabosil), chalk and wood flour will give you a strong structural filler that will hold a screw and fillers like talc and microballoons provide a softer, lighter filler that is easily sanded. Epoxy doesn't shrink as much as polyester does as it cures, so you may want to use epoxy to mix up your own filler rather than having to make two passes the way one typically does with poly-based fillers. Then again, the cure times are so much shorter with poly fillers that it's probably more an issue of cost than time. You could also use wood filler or wooden plugs.

Coincidentally....starting on page 13 of the most recent issue of Epoxyworks (the West System publication) there is actually an article on applying polyester-based gelcoat over epoxy including some bond-strength testing they did.

Any chance I can find something that will work at a big box store like HD or Lowes for a gap and hole filler? I'm at the point where I need to start filling gaps and counter sink screw holes so I can start putting down my epoxy. Speaking of epoxy resin I heard someone say just to use that. Well today I mixed some up to try on a board with a few holes and mixed per the directions with a 2:1 ration of resin to hardner then stirred for 2 minutes. The epoxy is like syrup. That's fine on a horizontal surface but no way it's going to fill a hole or a gap on a vertical surface. It would just run out. I'm kinda stuck trying to figure out where to go from here as tomorrow is my last chance to work on it for probably 10 days or so. I wish I could at least find something to fill the holes so I can come back from work after 10 days and start sanding. Any help appreciated.


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It sounds like you are a complete novice with epoxy. I had very little experience with it when I started covering TPCE but have learned a bunch along the way.

I highly recommend reading West System's use guides before you get started. Lots of good info (including safety precautions).

Here is their fillers page. Read that, too.

Your brand of epoxy may be different in its mix ratio, but the techniques will be the same.

Well it's a done deal now. I've filled the holes and sanded all day and have my first coat of DWX Epoxy on. I'm planning on 3 coats of DWX with a light sand between coats followed by 3-5 coats of paint. Haven't decided yet on what to use for paint over the epoxy. Should I go Latex or Enamel? Any brands better than the others. Also this needs to be something found at Lowes or Home Depot as I'm rushed for time. I know not a great thing to be rushed but I have about 3 weeks to have this complete.

Haven't been on the board much lately so I hadn't seen your followup question. Yeah, resin alone (neat) is no good as a filler...as you found out.
Definitely check out the West links KC put up - lots and lots of info. They will discuss paint in there somewhere.

If you are pressed for time, you might want to go with latex. By the time you get it painted, enamel may not have time to cure hard before you hit the road with it.
Check out fiberglass deck paints but check the label about using them on vertical surfaces.

What did you wind up using for filler ?