I would like to use something other than Bondo for my Weekender.
Someone told me about a fiberglass product called fibertech - which I searched the internet and didn't find.
Smith coat makes a fantastic wood puddy/filler product, but brutally expensive.
Any other options out there that have worked for others?
Jeff, Silver Tip fairing compound is wonderful for small jobs and fairing, else make your own thickened epxoy with filler additives. Buying in bulk saves a lot. Bondo is polyester and has adhedsion problems. Unless totally encapsulated it will allow water penetration under the edges eventually causing failure.
Bondo also has the unhappy issue of "circling out" from vibration. This isn't as big an problem on sailboats, unless they have a gas outboard for power, but on a powerboat, it will fail pretty quickly.
Typically if used over a fastener hole it will develop a circle shaped crack (hence the common name) then the circle will fall off the boat. In areas where used as a surface filler, the feathered edges begin to lift (from vibration) which promotes more lifting, moisture ingress and the downward spiral, until it fails.
There are a few "surface filling" products available, most are polyester based (like Bondo) and though I've heard many say some of these work well, I'll stick to epoxy based fillers, just to insure they stay stuck.
Mixing up fillers for surface smoothing is a bit of practice and experience, the more you do, the better you'll get at it. I can do it by eye as I'm mixing up a batch, using the mixing process (which I do on a large, flat, smooth surface) as I drag the putty knife back and forth. You kind of get a "feel" for the right consistency in the application you're about to use it. Thicker for vertical or overhead work, thinner for down hand or horizontal efforts. This is also true of the different materials used in the mix.
I can see how a beginner may want a "filler" in a can type of product and System Three and a few others are offering just this. These pre-mixed products are nothing more then what we do when mixing our own, but calculating the type and quantity of fillers for the mix is done for you. This can be real handy. I've used a few of these and they worked fine, but my only complaint was some were too thin for over head work, requiring adding more filler, which isn't the reason I wanted to use the pre-mix stuff in the first place. In short, if I have to modify what's in the can, I'd rather save some money and mix up my own, which is a lot cheaper in the long run, but requires more effort (mixing).
When we went up to help Brit with his boat he uses epoxy and the dust he pulled out of his belt sander. Real fine powder and worked pretty well.
I've been doing it like Brit using Epoxy and fine sawdust from my sander, I ran out of sawdust and got some from rakka and it works fantastic.
Brian.
:lol: Same as Brit, except I rob the dust collector in our woodshop at work (but I only take the really fine stuff !!)........
I save all the wood flour from my ROS in a plastic container and use that for filler. If I run out I take sawdust from the bag under the table saw (Ill never run out of that) and run it thru a flour sifter. Karl is right tho, micro-balloons sand much easier.
Sold!... Sold to the gentlemen who recommended epoxy and sawdust! Sounds good. I am sure it sands down okay too. Thanks for all your input. Much appreciated.
If youâre filling screw heads I strongly suggest using microballons, because of the sanding factor.
Wood flour and epoxy mixture sets up harder than wood, when you sand it takes away the material around the faired area and leaves valleys.
If you use wood flour and run out just use bread flour.
I use it all the time, to lighten fillet shades. Iâve even used 100% bread flour fillets on kayaks. My 5 year old favorite kayak has all bread flour fillets.