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Bodywork (filling holes and cracks)
Sierra - 15/10/12 at 10:09 AM

Hi guys just after some advice on cleaning up the fiberglass shell. I'm going to be vinyl wrapping the whole tiger avon but before I do I want to repair some cracks and also fill some holes that are left from old lights, mirrors ect.
Can some one give me a list of the products I'd need and where I can get them at a good price.
Thanks

Charlie_Zetec - 15/10/12 at 10:35 AM

Well the first thing to note is that there are two main types of resin available for fibreglass; polyester and epoxy. Any car shop (Halfrauds etc.) will have a nominal DIY kit available that will have chopped strand matt (CSM), resin, hardener in it. Some might even have a thin wire mesh included, or a surface tissue as well.

If it's just cracks in the surface you're looking to repair, i would suggest just getting some epoxy resin and hardener, gently opening up the crack on the surface slightly, cleaning with acetone, and carefully filling the crack in with the mixture. A very crude analogy is repairing render on the outside of houses. For those that wonder why I suggested epoxy resin, it's because "new" polyester resin doesn't adhere too well to "old" resin, so to speak.

If the holes/cracks are more structural and go through the panel, my advice would be to patch the back of the affected area using epoxy resin again, with the CSM (maybe mesh as well, depending how bad the damage is) to provide structural reinforcement. You can then decide if you wish to work on the outer (visible) side with the above process.

I mentioned in the opening paragraph about a "surface tissue". This is for external use, to provide a smoother surface finish (in the absence of a gelcoat - will explain shortly). Just remember that any sheet or extra material you add to the outer surface will require smoothing in!

Gelcoat is a typical finish to GRP (glass reinforced polyester) panels for a coloured/smooth/UV resistant finish. This is not something that is easy to do in terms of matching colours etc, and is probably not required in this case.

From what you've descrided, I'd say you want to glass the inside of the holes etc. with CSM and epoxy resin, then my advice would be to just fill the holes/cracks from the outside using resin only, sand back to smooth finish, maybe put a touch of paint over them if you think it may show through the colour of the wrap, then cover it all in vinyl!

That's just my 2p's worth, and I'm sure someone will come along shortly and tell you something totally different!

twybrow - 15/10/12 at 10:50 AM

Charlie - there is no need to use epoxy in this application. The bodywork will be made of CSM and polyester, and this is what you want to use to repair it with. If you have taken the time to sand/grind back the cracks, then you wll have no problem with adhesion. Just make sure you have gone all the way back to the end of the crack and enlarged it a little before filling back in. You could look to use gelcoat filled with a little a little talc, or colloidal silica - that will give you a paste, which will fill cracks very nicely. To be honest, regular car body filler will also do the job (this is polyester based) if you have adequately prepared the surface (as Charlie says - abrade, then clean up with acetone before you start).

Also, Halfords etc is a very expensive way of buying fibre-glassing materials. Try CFS - they also have lots of useful info on their website - give them a ring, and tell them what you want to do, and I am sure they will give you just what you need for the job - and a lot cheaper than those kits from Halfords!

Charlie_Zetec - 15/10/12 at 10:59 AM

quote:
Originally posted by twybrow
Charlie - there is no need to use epoxy in this application. The bodywork will be made of CSM and polyester, and this is what you want to use to repair it with. If you have taken the time to sand/grind back the cracks, then you wll have no problem with adhesion. Just make sure you have gone all the way back to the end of the crack and enlarged it a little before filling back in.


You're probably right in this case, I'm just used to working in a more industrial environment with these materials! If it were me, I'd still want to use an epoxy resin, but then again I don't pay OTT money for materials as I work in the industry.....

As he said, it's going to be vinyl wrapped anyway, so as long as the surface is relatively smooth, I don't think he'll need worry about such issues.

twybrow - 15/10/12 at 11:09 AM

quote:
Originally posted by Charlie_Zetec


You're probably right in this case, I'm just used to working in a more industrial environment with these materials! If it were me, I'd still want to use an epoxy resin, but then again I don't pay OTT money for materials as I work in the industry.....


Me too mate! What do you do? This is what I do!Skip to 1:30 and you can see the tool my team is just completing! She's a whopper!

Sierra - 15/10/12 at 11:29 AM

Thanks for the info guys much appreciated
So to recap
Cracks
1- sand back to open up crack more
2- clean
3- fill with epoxy resin or gelcoat with talc
4- sand smooth

Holes
1- fiberglass sheet round the back
2- fill hole with epoxy resin or gelcoat with talc
3- sand smooth

mcerd1 - 15/10/12 at 11:33 AM

quote:
Originally posted by twybrow
quote:
Originally posted by Charlie_Zetec


You're probably right in this case, I'm just used to working in a more industrial environment with these materials! If it were me, I'd still want to use an epoxy resin, but then again I don't pay OTT money for materials as I work in the industry.....


Me too mate! What do you do? This is what I do!Skip to 1:30 and you can see the tool my team is just completing! She's a whopper!

^^ small world, are you involved with the V90's aswell ?
(a few of our cutomers are building them at the moment)

[Edited on 15/10/2012 by mcerd1]

twybrow - 15/10/12 at 11:36 AM

quote:
Originally posted by Sierra
Thanks for the info guys much appreciated
So to recap
Cracks
1- sand back to open up crack more
2- clean
3- fill with epoxy resin or gelcoat with talc
4- sand smooth

Holes
1- fiberglass sheet round the back
2- fill hole with epoxy resin or gelcoat with talc
3- sand smooth


The technique for filling holes depends on the size of the hole, but in summary:

1. Grind back the edge of the hole to produce a chamfer
2. On the finished side, stick something over the hole to provide a surface to layup onto - a sball hole can be done with masking tape, for larger holes I would use something like melamine/semi-rigid plastic/fibreglass sheet (but not something affected by the resin system) - apply release agent e.g. wax (or clingfilm can be used)
3. Working from the back side of the hole, apply gelcoat
4. When gelcoat is tacky, laminate over the hole extending onto to the existing laminate

I would avoid just filling anything bigger than a crack, as it will probably crack again.

twybrow - 15/10/12 at 11:48 AM

quote:
Originally posted by mcerd1

^^ small world, are you involved with the V90's aswell ?
(a few of our cutomers are building them at the moment)


We do all the R&D for all of the new blades (in particular my team is responsible for designing/delivering all of the composite tools for the manufacture of the blades) - the V90 is an older platform now, so not one I directly work on. I take it you work in the construction/installation side of things?

mcerd1 - 15/10/12 at 02:48 PM

quote:
Originally posted by twybrowWe do all the R&D for all of the new blades (in particular my team is responsible for designing/delivering all of the composite tools for the manufacture of the blades) - the V90 is an older platform now, so not one I directly work on. I take it you work in the construction/installation side of things?
^^ not quite - substation design...

[Edited on 15/10/2012 by mcerd1]

loggyboy - 15/10/12 at 03:49 PM

A good thing to so with cracks is to drill a small round hole (5-10mm) at the very end of the crack, this will limit the chance of the crack spreading further whilst being repairs and worked on, or even once its repaired.

Charlie_Zetec - 15/10/12 at 07:45 PM

quote:
Originally posted by twybrow
quote:
Originally posted by Charlie_Zetec


You're probably right in this case, I'm just used to working in a more industrial environment with these materials! If it were me, I'd still want to use an epoxy resin, but then again I don't pay OTT money for materials as I work in the industry.....


Me too mate! What do you do? This is what I do!Skip to 1:30 and you can see the tool my team is just completing! She's a whopper!


Nothing too exciting I'm afraid- I work (primarily) in the commercial vehicle industry, GRP laminates and composite panels as used in refrigerated & hard sided vehicles, as well as roof material!
Also do other items such as profiled material and tanks (as in storage, not military!) using continuous, discontinuous and chopper-gun sprayed methods. Exciting stuff, lol.

Sierra - 15/10/12 at 08:06 PM

Is this the kind of kit needed, I already have the sandpaper

Look at this on eBay:

Fibreglass Kit - 1 sqr m coverage - glass fibre repair

http://bit.ly/SYm46O

Or


P38 Easy Sand Car Body Filler 250ml & Fibre Glass Repair Kit & Grey Primer Paint

http://bit.ly/S01Vks


[Edited on 15/10/12 by Sierra]

Creative Andy - 22/10/12 at 05:34 PM

quote:
Originally posted by Sierra
Hi guys just after some advice on cleaning up the fiberglass shell. I'm going to be vinyl wrapping the whole tiger avon but before I do I want to repair some cracks and also fill some holes that are left from old lights, mirrors ect.
Can some one give me a list of the products I'd need and where I can get them at a good price.
Thanks

Hi Sierra

A really good company to get resin and fibre glass from is East Coast Supplies. I've been repairing fibre glass gliders and cars for years and the best way to carry out your repair is to:- Scarf out the damaged area...once you get through the gel coat it's amazing how long stress cracks can travel......grind out the damaged area going through the glass at a ratio of about 4 to one....so there's a sort of slope.

Then lay up a few layers of 100grams Chopped strand mat...although I always prefer to use twill weave cloth. Anyway once you have built up the ground out area, profile back to the original bodywork...and fill any slight imperfections. Sounds complicated..it isn't, but this was way the cracks won't come back. Any questions get in touch...best of luck. Andy.
westgatecomposites.com