Bondo Removal

[Anastasia]

The stem of my boat seems to have been faired or fixed with Bondo. I'm contemplating whether or not to have the boat bright above water. Should this Bondo-ization steer me away for brightness? Am I likely asking for more problems by trying to remove it?

Is there some special way to take Bondo off?

[imported_Conrad]

It depends on how much there is, and why it's there. If it's just a bit to fair the stem after some small bangs and bruises, you may be able to re-fair it to a different profile and finish bright. If there's a lot of it, maybe even structural, you'ld have to paint it to match as closely as possible with the surrounding wood, then finish bright, or forget about the natural finish.

The only way to get it out is sanding/grinding, or cutting with a dremel type tool. Try a small patch perhaps to see what you're up against. "Bondo" can be everything from polyester resin with talc fillers (very soft) to epoxy with ground glass fibers, or even epoxy with Portland Cement- extremely hard and strong. Good luck! ;) smile.gif

[rbgarr]

IIRC, Paul Haley (Giffy Full's partner) once pointed out that Bondo used as a patch or deep filler can be a place where rot will start on a wood boat, because it will not shrink and swell like wood does, thus letting water get in between it and the wood it 'attaches' to.

I don't understand the concept of Bondo as 'structural'.

[ 01-13-2004, 02:58 AM: Message edited by: rbgarr ]

[Anastasia]

Yes, I am concerned about this and in other areas where Bondo was used as a fix. These areas seem to have somewhat soft wood around them. I'm thinking I might take out these old fixes and put in dutchmen above the waterline and/or a filler below the waterline.

A bit more info on the Bondo placement. Along with being in the stem it was faired into where the lapstrake planks join the stem. There is evidence of a bang close to the stem below the waterline. If I manage to remove the Bondo, could I then use an expoxy such as a 5200 substite to fill in the gaps and possibly put in a dutchman where the bang was?

Yes, I am concerned about this and in other areas where Bondo was used as a fix. These areas seem to have somewhat soft wood around them. I'm thinking I might take out these old fixes and put in dutchmen above the waterline and/or a filler below the waterline.

[imported_Conrad]

Its pretty common to see "bondo" used to clean up around the plank ends, especially in older boats where a lot of swell/shrink cycles have left wide gaps. A dutchman, or other type of repair involving wood is the best way to go for the reasons mentioned above. But fillers are often used, and have their place. They won't usually last as long however, and can lead to new problems.

You need to be specific when talking about "bondo" (a brand name) and fillers. There is no comparison between true bondo and epoxy with powdered glass or silica mixed in. The later can be used with some success below the water line when applied to solid, dry, wood, and then kept immersed.

[Anastasia]

I spent the morning scraping off a lot of the "bondo" put on by previous owners. I used a heat gun and Proprep scraper. It had fibers in it and came off fairly easily. Some bondo is still in the grooves along with some putty. The joints where the planks come into the stem are now clearly defined. It was satisfying to reveal these lines again; in my view it adds more beauty to the boat. I have not yet discovered any structural damage at the stem; however, I have not scraped below the waterline.

[imported_Conrad]

It sounds like what you've got is what we call "tiger's hair", polyester resin with chopped mat fibers/waste mixed in. It can be fairly strong stuff, but the resin is weak, and responds well to heat or sanding. I agree it's best to show all the plank lines/ends at the stem- part of the "art". You may be able to fill any unusually deep seams with filler or urethane type caulk, but finish it with a depression, or concave surface, by running your finger or the end of a small bit of tubing over it to allow the lines/seams to show. smile.gif

One thing that has always pleased/amused me about removing other's repairs is that when you get back to the original surface, it may not be that bad. The repair process, when done by less skilled hands, tends to expand, often to the point where much of the original surface is lost. As the technician attempts to fair in his repair, the involved area continues to expand and grow. It's sort of like the hair-cut joke, where you keep evening it up, only to end up with a military cut-- but in reverse! When we are restoring old cars and grind off 30 years of repairs and bondo so as to start over with bright steel, the amout required to re-fair it is typically a fraction of what came off!

[ 01-14-2004, 08:01 PM: Message edited by: Conrad S. ]

[Anastasia]

Conrad, thanks for the advice on how to keep the lines of where the planks and stem meet visable. As a novice at this, I appreciate these pointers on how to reveal and maintain the integrity and craftmanship of the original boat design.

[blackduck]

You can remove it fairly easy with a heat gun and a scrapper. Use high heat it will soften up and you can scrape it out If your working on solid wood and not plywood you should be able to get all of it off. I use this method quite oftenin my shop. Good Luck