Classic cars forum & vehicle restoration.

steammart · Joined: 11 Apr 2011 Posts: 27

Some of you may have seen my morris 8 restoration, the rear of the body tub has been bodged up with fibreglass at some point.

What I would like to know is whats the best way of removing the the fibreglass but in a way as not to damage the metal underneath (or whats left of it). Is there a product that will disolve it?

Cheers
Martin

baconsdozen · Joined: 03 Dec 2007 Posts: 1119 Location: Under the car.

Nitric acid and ethanol both dissolve the polyester type fibreglass resin.If the resin is one of the epoxy type then they wont but the epoxy stuff isn't very common.
There is a commercial product thats used but I can't remember what its called,ask a boat builder they use it on fibreglass repairs.
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Rick · Site Admin Joined: 27 Apr 2005 Posts: 22447 Location: UK

I did read a suggestion of using (gently) a hot air gun - but you have to be mindful of the fumes it can create apparently. Not something I've tried or particularly recommend though, just what I read Smile

RJ
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Bitumen Boy · Posted: Fri Mar 23, 2012 12:10 pm Post subject:

Well, a twist knot wire brush used in an angle grinder will quickly get it down to dust, but if there's a lot of it then you won't be having much fun!

My guess, though, is that in all likelihood the original rust wouldn't have been well treated - unless, of course, they used red lead - and the corrosion may well have continued under the fibreglass, meaning that it won't really be bonded to much of anything. There's a fair chance that a bit of poking around will find a weak spot from where the stuff can be levered off pretty much complete... Rolling Eyes

Nick.S. · Joined: 08 Nov 2011 Posts: 64 Location: Manitoba, Canada.

apparently ethanol works to dissolve the resin, but i would have figured acetone would work well, perhaps even other industrial solvents like toluene and xylene would work as well.
you should be able to find acetone and toulene at a hardware store, and xylene can be found on fleabay.
good luck Very Happy

Nick.
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baconsdozen · Joined: 03 Dec 2007 Posts: 1119 Location: Under the car.

Ethanol dissolves the resin which is why fibreglass tanks are a bit of a no no with the newer fuels which contain it in varing doses.
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Thirty years selling imperial hand tools for old machinery(Now happily retired).

ajlelectronics · Joined: 04 Oct 2010 Posts: 168 Location: Gloucester

buzzy bee · Joined: 23 Nov 2007 Posts: 3382 Location: South Cheshire

Hi

If you use a grinder, Knotted Nylon discs are the thing to use, they will strip paint, filler, fiberglass, rust etc, and leave a good keyed surface to paint on, but it won't touch good steel.

Discs like these:-

http://www.signicn.com/bigpic/1/8/20101121164340.jpg

They are quite dear, but I think I stripped most of a car with about 5 or 6 discs.

Hope it helps

Cheers

Dave

Julian · Joined: 19 Apr 2010 Posts: 278 Location: Warrington

lowdrag · Joined: 10 Apr 2009 Posts: 1585 Location: Le Mans

Bitumen Boy · Posted: Mon Mar 26, 2012 8:37 pm Post subject: Re: Fibreglass

steammart · Joined: 11 Apr 2011 Posts: 27

Thanks for the replies, when I do attack it I'll let you all know how it went.

Handyman · Posted: Mon Apr 23, 2012 1:21 am Post subject:

As I do a lot of work with resins and fibreglass in dinghies and making car panels, I have found that once the resin has cured most solvents in any form do take a considerable time to dissolve any bonding.

The real trick is to wash off any resin that has not cured with acetone, but that does not answer your problem where the bonding has taken place. You could try using styrene monomer, but again, once the catalyst has help cure the resin, you will have a long, labourious and expensive task.

I sometimes use heat on my laminating rollers to burn off the resins, but it is a messy business and the fumes are not conducive to good health.

Ethanol will attack polyester resins but again the process is slow. I would be wary about using ethanol as it is again not very conducive to good health. The fumes can be extremely dangerous and poisonous.

If you decide to use any form of abrading/grinding, you must wear protective eye wear and a good mask designed to exclude the dust fitted with the right filter, not one of the cheap masks you can buy in a car factors.

If you are grinding the cured GRP, small pieces of glass are produced in dust form that can cause infection when absorbed into the eyes. The effect on lungs, if you breathe in the dust, it is even more disasterous as your lungs will develop infections caused by the glass that are virtually impossible to eradicate.

If you are not sure, get a professional to strip off the GRP.

Dick