Fiberglass resin removal

[R.J]

Dose anyone know a good chemical to remove fiberglass resin from a wooden hull?
I have been using belt sanders, but the underside of the hull is proven to be difficult.
There is no cloth on the hull just the resin. The hull is oak planked.

[NormMessinger]

No solvents. Sorry. Perhaps a heat gun and scraper to get the worst of it.

[Dutch Rub]

sounds like youre having some fun there! smile.gif

[Concordia..41]

I don't know of a chemical solution, and I don't think a heat gun will help either. If it was cloth coming up in places, a heat gun might encourage it to come up more, but it won't raise epoxy out of the grain like using a heat gun on varnish.

You may want to experiment with different sand paper brands (they vary widely not just in grit, but in effectiveness). I keep both Norton and 3M in a range of grits and am constantly surprised at how often I change back and forth.

Also experiment with a random orbit sander or even a grinder.

It's not supposed to be a party, but when you find yourself getting absolutely nowhere with a task, it's usually a good time to try a different approach.

Cheers!

[chucksw]

West System user manual says to use a heat gun at 200 degrees to soften epoxy. Use a paint scraper to remove most of the coating, then sand remaining. I found an angle grinder with 7" disk and 40 grit disks effective at removing bottom paint and would also sand right into epoxy. But if there is a thick coating with lots of area use the heat gun. Provide ventilation when heating and wear a good particulate mask and protective clothing and goggles while sanding. The dust is very irritating.

[Russell Sova]

He didn't say epoxy resin, he said "fiberglass resin" which I've heard everyone on this forum say self destructs. How is it that it adheres so well that it must be removed in so vigorous a manner?

[R.J]

It is not how it was put on, but the amount that was put on the hull. The hull itself is 34 feet long and the fool who had the boat before me coated the hull with this resin; which is ¼ thick in some places.
I found an attachment for my drill that will let me use a 5 inch sanding disk. So far it has been slow going. But it is easier to hold a drill over your head then a belt sander. Oak dose look lovely after it has been sanded.

[Todd Bradshaw]

That's a big enough boat that it's worth investing in the proper tools to do the job. A good, industrial-grade heat gun, like a Milwaukee, should soften either polyester or epoxy enough to start removing the goo, and may be your easiest (it still ain't easy) method. I'd rent one for a couple hours and try it. The fumes of melting resin are bad for you, so get a respirator and use it. With a job that big and resin that thick, I wouldn't be surprised if the process uses up most or all of the lifespan of the heating element.

Option #2 is sanding and has it's own set of obvious mess and health issues, but may go faster. A belt sander is a very hard tool to use and big areas that are supposed to wind-up fair. It would help to know whether it's polyester or epoxy resin when choosing the tool. The vast majority of random orbits are going to take forever to do the job with either resin. You need a big, right angle disk sander (7"-8") and something in the neighborhood of 36-50 grit, resin-backed floor sanding disks. This should be backed-up with a hard phenolic plate (not a soft foam pad or rubber backing pad) to prevent dishing the wood. Some folks add a thin (1/2" or less) foam pad between the sandpaper and the hard plate, but on oak, I wouldn't bother.

With polyester resin, you can use a machine that runs as high as 4800 RPM, like Black and Decker's "Wildcat" models. That kind of speed will overheat epoxy resin and it will quickly begin to smear and plug-up disks at an alarming and expensive rate. Something like a big, but fairly slow (1750 RPM) sander/polisher, such as those made by Milwaukee, will allow you to sand much longer on most epoxies before the disk gets filled. It will also work on polyester, but a bit slower. In any case, you're going to need a fair number of disks as they are going to fill up. When they do, the sander gets jerky and your ability to get the goo off without gouging the wood goes downhill.

These machines are heavy and using them under a hull is a real bear, but they will cut and remove the stuff quickly and completely. If anybody knows of a dainty little Random orbit that will do the job, great, but I'll believe it when I see it. In the mean time, the proper technique with a big disk is to go back and forth, just barely lifting the leading edge of the disk and trying to cover large areas uniformly by keeping the sander moving and not dwelling long enough on small spots to make a dent. Some people do better by removing the screw-in, right angle handle near the sander's head as it causes them to tilt the disk too much and that causes chop-marks. Instead, you hold one hand aft, on the trigger grip, and the other cradles the head of the sander (watch your fingers and wrists). That way you reduce your tilting leverage and the disk stays flatter.

Obviously, working a 12 lb. sander back and forth while above your head, on your back or upside-down is quite tiring for your arms and it's hard on your back. Take plenty of breaks and rest before you get so tired that you're losing control. The edge of the disk wil slice your flesh wide open much faster than it will cut resin or oak. In short, pray that the heat gun and a scraper will do the job, but if it won't, this will.

[ 10-17-2003, 01:48 AM: Message edited by: Todd Bradshaw ]

[ion barnes]

Todd is right on the money with the grinder. Bin there don that with a 9" unit and it works. For overhead work I would try suspending the grinder from a sling. Got to watch you dont cut the sling and probably not recogmended by WCB but be careful.