TOPIC: Filler recommendations

I am getting ready to start the repairs and the infinite filling and fairing on the Glastron top. What do you all recommend for a filler? I was thinking Bondo-glass, but not sure. I'd appreciate thoughts

I'm about to go out and mix up a batch using talc (talcum powder) and polyester resin myself Todd, I'll let you know how it turns out. I've been told that pulverized lime works well too, but I didn't make it to the feed store yesterday before they closed.

I considered ordering some of the specialty products made specifically for fairing, but the budget just doesn't allow it right now. I'm on the beginning of the learning curve with this, but it seems that using poly resin kinda limits what you can mix with it for fairing?

the Tudor,

personally, i don't think that ANYTHING compares to "peanut butter" made from slow-setting epoxy & pulverizrd agricultural lime & it's CHEAP, compared to most commercial "filler putties".
(i like cheap.)

just my opinion, satx

I was told that the worst thing to use on marine applications is Bondo. It just doesn't hold up. The other advice is sound. Slow setting epoxy and lime is the best advice. It gives you plenty of open time and it's easy to block. Also, you can use a good high build primer. I'm using Proline.

I like the epoxy-lime mixture. No compatibility problems between lime and primer/paint/gelcoat?

thetudor wrote:

I like the epoxy-lime mixture. No compatibility problems between lime and primer/paint/gelcoat?

i wouldnt try to gel-coat on top of a epoxy base filler , there will be bond issues . Paint would be fine though .

As previously mentioned, avoid Bond-O and pretty much ALL auto fillers, most of them will absorb water over time, which is not good on a boat!

If you are looking for a pre-mixed filler, 3-M Premium is great stuff. It's vinylester based, cures quickly, and sands nicely. Keep in mind there is more than one type of 3-m filler, one is a heavier structural filler, which is far more difficult to sand. The drawback to 3-M filler is that it is EXPENSIVE.

Talc and lime can both be used, but are pretty heavy. Talc can also absorb water (which is why BONDO is bad on boats- Talc is the filler material! ), which is bad news.

I use U.S. Composites SM fairing filler-

uscomposites.com/fillers.html

It's inexpensive stuff. You need to mix it with EPOXY resin- It can't be used with polyester... Judging from the color, it's got some phenolic microballoons in it, which is why it's not used with poly. They also sell 3-M Microballoons, which make a great filler, too, and CAN be used with Poly. I usually buy the 5 qt tubs, which are in the $10.00 range for both fillers.

A great advantage of mixing your own is that you can vary the amount of filler that you put in to suit the application..

You need to mix it at a ratio of about 2 parts filler to one part resin to get the consistency that you want for fairing filler, to give you an idea of how much you'll need.

thetudor,

i can see NO reason to re-gelcoat, especially below the waterline, given the multitude of colors of marine and/or "industrial" epoxy-based paints that are available.

the epoxy paints are certainly easier to "shoot" than gelcoat on a used boat, as most will"self-level" & fill imperfections in the hull surface (to some degree).

yours, satx

Hi Tutor,

I've used Bondo-glass for years and its worked great for me.

CraigLam, its not the same thing as Bondo filler. Bondo-glass is harder and filled with chopped fiberglass... it goes on green and sands out gray. Bondo filler goes on and sands out pink, very soft.

For bigger area smoothing jobs that need no structural component, I mix 3M glass balls (microballons) into my resin.

Dean

I have used Dyna glass and a fiberlay product that is like a resin jelly that you add a hardener to. It works great for faring and filling and leveling. When you say Bondo on boats attracts moisture Hard to figure how when its covered with Primer than a good coat of paint and these boats are mostly kept in a garage and get wet maybe 12 times a year then washed and toweled dry ? I could see the problem if it was below the waterline stored in the water at the dock or sitting out in the rain. You can also mix Fumed Silica with Resin to make a paste . I filled some cracks with some color matched Gel coat and the silica and you can't see where they were

I've used the bondo class plastics but better ones with great success but my boats do not sit in the water. Mine are pulled every use. It is on the roof, I see no problem what so ever. The chopped fiberglass products are great too. In fact I love them. They are strong and versatile.

If you're going to be gelcoating over the filler material, it's important to remember that you need to use either polyester or vinylester based products. Gelcoat does NOT adhere well to epoxy. I love using Epoxy based fillers due to the longer working time but Gelcoat and Epoxy do not play well together. Mixing your own is the way to go due to the consistency factor. When you buy it in a can it's usually like creamy peanut butter and I like mine to be more like Mayonaise. Flows into cracks and crevices on horizontal surfaces much better. Vertical require thicker consistency so you just add a bit more filler to the resin. I agree with andrew on the filler from uscomposites for expoxy. For Poly I use Q-Cells and Cabosil for above the waterline and 3M Glass Bubbles for Below the waterline.

I like the uscomposites.com products as well and found that you can call them for free advice. I used their free advice well on the Glastron project. Sometimes a minute on the phone with them clears up alot of confusion.

I'm going to try the vinylester fairing compound from LBI Fiberglass (my local fiberglass supplier - www.lbifiberglass.com ). I'm looking for something with a little more strength for filling holes and was thinking something with fibers. I've used the 3M stuff in the past, but not with the fibers. It is expensive ($87 per quart at West Marine) and think there has got to be a better solution.

For filling holes, I mix my own "Tiger Hair" Resin, Cabosil and torn, shredded CSM fibers. Works Great!! Poly or Epoxy doesn't matter.
For Easy Sanding Fairing the uscomposite stuff is hard to beat.