Epoxy fairing compound / filler

[JonnyBoats]

For filling gouges on the side of the hull (fiberglass) what sort of fairiing compound or filler should I use?

Is epoxy fairing compound basically epoxy with fillers added to make it more viscous?

Does anyone used Interlux Watertite filler or Interfill epoxy filler?

[Quetzalsailor]

John,

I use the West system components. They make two fairing compounds as well as a bunch of other additives. One is microballoons, a russetty-purplish color and the negative is that the balloons are thermoplastic. They tell you not to use that filler under dark paint or on deck since it may deform with the sun's heat. I used it in heaps to bed my new mahogany veneer on the Flying Dutchman; the color is compatible for where fits were imperfect. Their other filler is, I think, called microlight. It's yellow, fairs and sands very nicely.

Following their instructions, I wet out the surface to be filled with neat epoxy and then add the filler to the remainder of the batch. Add as much filler as you can wet out in the batch: quite alot by volume. Epoxy with just a little filler is hard to sand and can creep before curing. Find out whether the proposed paint will be happy over epoxy.

There are lots of other suitable fillers. Certainly polyester putties and fillers are perfectly suitable, presuming the substrate will accept it. You can't use polyester over epoxy. If you are working out in the paint layers, then there are 'glazing putties' made for minor imperfections.

You have a little research to do before hopping in. Lots of horror stories in Professional Boatbuilder about incompatible fillers, substrates and paints.

How's the project coming?

D

[Ceasar Choppy]

Remember, you can use epoxy over polyester, but not polyester over epoxy.

If its just gouges in the gelcoat and you don't plan on painting, use the poly fillers and/or gelcoat to repair depending on how deep the gouges are.

If you are going to paint over it, then epoxy with the fairing fillers is a good way to go.

[rshowarth]

Remember, you can use epoxy over polyester, but not polyester over epoxy.

If its just gouges in the gelcoat and you don't plan on painting, use the poly fillers and/or gelcoat to repair depending on how deep the gouges are.

If you are going to paint over it, then epoxy with the fairing fillers is a good way to go.

I just applied fiberglass with epoxy to the nose of my daughters' Sunfish. It had damage from hitting the dock too hard when they were coming in. I had intended to fair and cover with white gelcoat. I do not intend to paint.

Is my next best option to color epoxy with white pigment?

Thanks

[Tim]

One is microballoons, a russetty-purplish color and the negative is that the balloons are thermoplastic. They tell you not to use that filler under dark paint or on deck since it may deform with the sun's heat.

It's the 410 Microlight that is incompatible on decks or under dark paint because of the heating problem.

410 MicrolightTM
410 MicrolightTM is the ideal low-density filler for creating a light, easily-worked fairing compound especially suited for fairing large areas. Microlight mixes with greater ease than 407 Low-Density filler or microballoons and is approximately 30% easier to sand. It feathers to a fine edge and is also more economical for large fairing jobs. Not recommended under dark paint or other surfaces subject to high temperatures. (Italics mine) Cures to a tan color.

[Tim]

I just applied fiberglass with epoxy to the nose of my daughters' Sunfish. It had damage from hitting the dock too hard when they were coming in. I had intended to fair and cover with white gelcoat.

With care and proper preparation, you can gelcoat over small repairs. It's not recommended as a general rule, however.

Read this for more information: Polyester over Epoxy

[Ceasar Choppy]

When they say "properly prepared" West System epoxy, do they mean properly mixed? There is no other indication of what "properly prepared" means in that article.

I'm put gelcoat over epoxy in small areas, many times, the gelcoat popped off-- I suspect it is the fact that gelocat/poly resins shrink more than epoxy does and that is why you don't get a good bond.


As for using the pigment in the epoxy, that pigment doesn't offer any UV resistance and the epoxy will eventually flake off.

[rshowarth]

Tim and Ceasar-


I will follow the preparation instructions provided by West and see what happens. They referenced:

Proper surface preparation will prevent these problems. (See 002-550 Fiberglass Boat Repair & Maintenance, Section 2.2.1 for details.)

I have their pamphlet at home and will refer to it for guidance.

Thank you,

[Ceasar Choppy]

Its been a while since I actually read the manual, but I've always sanded the area with minimum 150 grit, wiped down with acetone, wetted out the surface, and applied the epoxy. Then wash off the amine blush after it cures.

When I got my boat, it had a lot of poorly installed deck hardware that I removed. I ground out the mounting holes and filled with epoxy, but decided not to remount most of the hardware. Except there were all these damned holes!

So that I didn't have to re-paint, I covered the small epoxy-filled holes with gelcoat.. This is more of a temporary fix until I get around to redoing the decks a few years down the road. Out of 50 holes, I would say the gelcoat "popped off" 10 of them. Of course part of my problem might be that I was inexperienced in using gelcoat. :)

[Rachel]

Does anyone used Interlux Watertite filler or Interfill epoxy filler?

I've used Watertite twice: Once a number of years ago (back when it was "VC Watertite") to fill in a bunch of non-osmotic blisters on my Montgomery, and then just last week to do the final fairing on the ex-though-hulls I filled in on my Alberg.

I found it pretty agreeable to use both times. It's supposed to have a certain window after it cures where it's "easy" to sand, but I've never been able to get back to the job in time (for example, I was working weekends on the Monty, and a week was more than the easy-sand window) to take advantage of that. Still, it's certainly no harder to sand than any other epoxy.

It's handy to mix, as you just plop equal sized globs of blue and white on a mixing board and stir them together (note that the older formula was 1:2 but now it's 1:1).

This time around I might have chosen something else for the little bit I had to do, but it was what was handy, so I used it.

Rachel

[deckhand]

system 3 makes an epoxy that you can gel coat over. Also, the type of putty all depends on how much fairing you have to do. I have a ton so I found a cheap way to make something very very similar to system 3's quick fair.

Check it out here http://dkyrejko.com/hobyn/?p=10