Fiberglass filler

[Jeffery Carson]

I've a fair amount of experience dealing with fiberglass in architectural fabrications, but little in boats. Is there any reason I can't use automotive type filler (Bondo) instead of the more expensive marine fillers?

Jeff

[JRL]

You can use bondo.

Marine filler most of the time is vinyl ester based, so it is stronger, and does work better. It also appears to be finer grained (smoother?), not really sure how else to say it.

Both use talc, glass bubbles, etc... as filler material

[PAR]

Don't use Bondo or other polyester automotive style of filler. It absorbs moisture, it doesn't stick very well, it "circles" out around fastener heads and will vibrate off a powerboat in short order.

Most of us make our own filler mixtures, usually application specific to get the qualities desired in the particular project. Hard fillers for bearing surfaces, strong fillers to reinforce a bond or laminate, easily sanded fillers to fair a surface, heat resistant fillers, etc. There are a multitude of different materials you can use as a filler.

Log onto WestSystem.com or another manufacture site and check out the different fillers available. Some manufactures are offering premixed fillers, which is an option, but more costly then mixing up your own.

[fiberglass jack]

if you use bondo make sure u buy a extra can, and keep a weekend free because you will be repairing the repair. bondo is for cars not boats, i have a fiberglass repair shop and do alot of boats, the amount of bondo i see used in old repairs having to be repaired again is amazing,

[jimslade]

I agree, bondo is for cars. Waterproof fiberglass filler can be used. I like the long hair glass. It seems to stick better.

[bewylde]

One thing that can be done is that you can mix bondo with gelcoat, and substitute MEK instead of the bondo hardener. This gives you a tougher, more bondable product, not to bad to work with, with a great end result. Probably not recomended, but it does work great-i have had no comebacks using this mixture over quite a number of years. Bondo is for cars, but this makes it marine applicable.

[bewylde]

Also, shortstrand and longstrand fillers work great, (another automotive product) but they do end being a little hard and brittle-therefore being susceptable to poor impact resistance. The same as straight bondo, it will come off in chunks.