microballoons or flox?

alpinelakespilot2000 · #1 09-15-2007, 05:44 PM

I'm building a fiberglass rear skirt for my slider. Using tape as a mold between the canopy and the aft skin, I'm left with a small dip in the fiberglass layup where the tape sagged. At some places in the valley, the fiberglass is maybe 1/16-3/32" below the top surface of the fiberglass sitting on the canopy and aft skin.

I have both microballoons and flox. I understand flox has some strength qualities that microballoons does not, but does filling the sag described above with flox as opposed to microballoons serve any useful purpose here? Is flox even used for this kind of thing? Would it, for example, provide a tougher top exterior surface for my canopy skirt than microballons? Would it adhere to the cured, and peel-plyed, fiberglass any better? Does it sand or finish out any better or worse?

Any thoughts for this fiberglass novice much appreciated.

Paul Eastham · #2 09-15-2007, 05:52 PM

Flox is far harder to sand, and you may damage surrounding areas if you're not careful. Pure microballoons are a little soft, but probably fine... I know some guys who use a mixture of both for nonstructural applications where they want a little extra durability.

gpiney · #3 09-15-2007, 05:55 PM

Quote:

Originally Posted by alpinelakespilot2000

I'm building a fiberglass rear skirt for my slider. Using tape as a mold between the canopy and the aft skin, I'm left with a small dip in the fiberglass layup where the tape sagged. At some places in the valley, the fiberglass is maybe 1/16-3/32" below the top surface of the fiberglass sitting on the canopy and aft skin.

I have both microballoons and flox. I understand flox has some strength qualities that microballoons does not, but does filling the sag described above with flox as opposed to microballoons serve any useful purpose here? Is flox even used for this kind of thing? Would it, for example, provide a tougher top exterior surface for my canopy skirt than microballons? Would it adhere to the cured, and peel-plyed, fiberglass any better? Does it sand or finish out any better or worse?

Any thoughts for this fiberglass novice much appreciated.

Flox is next to impossible to sand. Dry micro is easy. Flox is only used for structural uses.
You now know why tape is a poor mold material. You would have been better off using a thin sheet of balsa covered with clear packing tape for release.

I would just fill it with dry micro and forget it.

Allen231ah · #4 09-15-2007, 06:28 PM

I use a lot of POLY-FIBER SUPERFIL part number 09-28250 from ACS . It is easy to sand and will adhear very well .

az_gila · #5 09-15-2007, 06:42 PM

I would vote for WEST Epoxy and their 410 filler...

This combination is works well, is easy to apply and easy to sand. I would only mix enough microballons in to make the mixture non-runny...

gil in Tucson

alpinelakespilot2000 · #6 09-15-2007, 06:57 PM

Quote:

Originally Posted by gpiney

You now know why tape is a poor mold material. You would have been better off using a thin sheet of balsa covered with clear packing tape for release.

Probably a good idea, Greg. I'm just following the experience of a couple other builders who ended up with nice skirts layed up over tape. The nice thing about fiberglass, though, is that it's pretty cheap so if this first one doesn't work I'll build another one and check around to try to find a source for thin balsawood. Maybe then I wouldn't neet to use much of any filler. Not sure I'll be able to find it locally though.

If the microballoons don't go well, I'll give Superfill or the 410 a try. I'm just trying to cut down on the number of cans of filler I have laying around.

Thanks for the replies.

vlittle · #7 09-15-2007, 08:59 PM

Quote:

Originally Posted by gpiney

Flox is next to impossible to sand. Dry micro is easy. Flox is only used for structural uses.
You now know why tape is a poor mold material. You would have been better off using a thin sheet of balsa covered with clear packing tape for release.

I would just fill it with dry micro and forget it.

I did a lay-up of e-glass on a waxed piece of plastic laminate (countertop material), cut out to make a skirt, then used that as the base for further layups.

See:

alpinelakespilot2000 · #8 09-15-2007, 09:42 PM

Vernon-
Nice skirt! Any hints on how you layed up the "dog house"? I've found that fiberglass doesn't like inside corners very well but your's appear to be relatively square compared to other fiberglass skirts I've seen. Again, looks nice. Thanks for the pics.

vlittle · #9 09-15-2007, 11:36 PM

Quote:

Originally Posted by alpinelakespilot2000

Vernon-
Nice skirt! Any hints on how you layed up the "dog house"? I've found that fiberglass doesn't like inside corners very well but your's appear to be relatively square compared to other fiberglass skirts I've seen. Again, looks nice. Thanks for the pics.

My recollection of the doghouse is hazy, but as I recall, it's got a lot of micro on top of the initial cloth layups. The initial layups for strength, and the micro for shape. This photo helps. Lots of sanding, of course!

Vern

More photos http://www3.telus.net/aviation/flyin...py_photos.html

penguin · #10 09-16-2007, 02:03 AM

Flox is used to thicken up resin when making a layup if the straight resin is too thin and will not stay where you want it. Can also be used to get a good corner - if the mold has a sharp corner then put resin/flox in the corner and lay up over it. As noted above it is hard to sand and heavy.

Micro is used to create a filler from resin and has all the structural properties of filler (ie none), but it is easy to sand.

If you're worried about durability another couple of layers of glass might be the answer.

Pete