Hadders
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| posted on 16/8/10 at 08:06 PM |
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Strengthening fibreglass
I have some lightweight race- spec bodywork and want to strengthen it. What's the best way to add a layer or two of matting to thicken it up?
At the moment it just looks like gel followed by a single sheet of mat then resin. The matt looks like the fibres run at 90 degrees to each other
woven together. I've got other parts that are thicker and they look like they have a layer of mat all mixed up, not in neat lines. Is this
what is called chopped strand mat?
Bodywork hasn't been used yet so wondering if i can just stick another layer on to add strength.
Thanks in advance for any advice.
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RazMan
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| posted on 16/8/10 at 08:09 PM |
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Yep, that's the easiest way - just wash it off with acetone (to remove any contaminants) and lay up another layer of mat & resin. Wet out
the old fibreglass with resin, lay a soaked layer of matting, and roller or stipple it down to remove air bubbles. It's suprising how much extra
strength you get with just one layer.
Other ways to strengthen involve using resin rope or balsa sticks which can give strength in specific areas like edges or large panels.
You can always apply a flowcoat layer as a finishing layer - it adds a little more strength and makes the finished bodywork impervious to light,
making it appear thicker.
[Edited on 16-8-10 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Hadders
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| posted on 16/8/10 at 08:23 PM |
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Thanks Razman. Should I lay the new matting at 45 degrees to the current layup for strength or does it not matter?
What spec of mat should I use? Is there a standard thickness / weight to use for bodywork? What resin should I use?
TIA
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RazMan
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| posted on 16/8/10 at 08:50 PM |
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I am not an expert my any means so don't take this a s gospel 
It's not really important to get the direction right but if you can, try and lay it in a 'new' direction as it will help the
strength a little. Just pre-cut your shapes to make things easy and quick (remember the resin has a very short working life in hot weather).
Your local body finishing supplies man will probably give you advice on the weight of mat to use - I would just use one layer of fairly heavyweight
(600gm) or, if you really want to push the boat out, two layers of lightweight (300gm) for a little more strength and use bog standard poly resin. You
can get really posh and go for bi-weave or even fabric but TBH that would probably be overkill for your project.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Hadders
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| posted on 16/8/10 at 09:04 PM |
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Thanks Raz. Appreciate the info.
Cheers
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designer
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| posted on 16/8/10 at 10:11 PM |
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I once strengthened a panal by glueing strips of Balsa onto it and then glassing over it.
This, effectivley, strengthened the panel by turning the balsa into tubes.
This way might need less fireglass than covering the whole part.
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trextr7monkey
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| posted on 16/8/10 at 10:16 PM |
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Loads of info on the East Coast Fibreglass site - based in South Shields if you are Googling-and if you want more you can just phone the guys up. They
ran some courses which some folks from here went to
atb
Mike
http://www.flickr.com/photos/14016102@N00/ (cut and paste this dodgey link)
Our most recent pics are here:
http://s129.photobucket.com/albums/p211/trextr7monkey/
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Angel Acevedo
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| posted on 17/8/10 at 02:56 AM |
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quote:
Originally posted by designer
I once strengthened a panal by glueing strips of Balsa onto it and then glassing over it.
This, effectivley, strengthened the panel by turning the balsa into tubes.
This way might need less fireglass than covering the whole part.
You can do small rolls of newspaper and fiberglass over them.
they only serve to form tubes which in turn increase rigidity. these cost less than the balsa
Beware of what you wish.. for it may come true....
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Benonymous
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| posted on 17/8/10 at 04:00 AM |
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Just another note for your prep. If the item was a single layup then it's possible (not probable) that the manufacturers used
"waxed" resin. This will leave a film of wax on the surface after curing. It would be best to give it a light sand and then a wash with
resin.
When I built the carbon fibre desk for work I used release wax on two of the surfaces of the mould (top and bottom not the front) and I sanded and
washed with acetone and bugger me if that still didn't shift it. I had my finish coat peel off and had to do it again on those surfaces.
[Edited on 17/8/10 by Benonymous]
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Hadders
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| posted on 17/8/10 at 06:54 PM |
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Thanks all. Very useful info.
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Angel Acevedo
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| posted on 17/8/10 at 07:44 PM |
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I did a cover for a sailboat with Styrene foam covered in newspaper and after a few weeks the fumes dissolved the foam leaving a void in the cover.
I don´t know how this affected the weight of the piece as it was not important.
Beware of what you wish.. for it may come true....
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