Board logo

GRP storage
doughie - 14/12/06 at 03:40 PM

whilst waiting for my GRP bodyshell (locost) am thinking about storage...

any problems storing outside?? apart from theives!

[Edited on 14/12/06 by doughie]


graememk - 14/12/06 at 03:45 PM

when i left he bonnet off my car it went out of shape


nick205 - 14/12/06 at 03:50 PM

most of my bodywork was stored outside under a tarpaulin before it was fitted and doesn't seem to have suffered any ill effects.

Like Graeme points out it's worth considering how you place it so as not to deform any parts over time though.


twybrow - 14/12/06 at 04:26 PM

Make sure you keep it cool and out of direct sunlight. Ideally it should be held relatively rigid and not allowed to deform. Fit some wooden battens to the back of the part to help support it until it is ready to use. Hope this helps.


RazMan - 14/12/06 at 04:28 PM

New fibreglass tends to 'move' for the first 3 months of its life and the main thing to be careful of is temperature extremes, especially direct sunlight. Also, if left unsupported you will find that shut lines change.
If you can, make a frame to keep everything in shape.


tri - 14/12/06 at 04:31 PM

we left ours under the house (same as outside but more secure) was fine when we went back use it just make sure its flat like everyone else has said

tri


Syd Bridge - 14/12/06 at 05:28 PM

If any bodywork deforms in the sun, what will it be like with a hot engine under it??

This is a symptom of using cheap resin with a low Tg point. (glass transition ie hard to putty).

If any bodywork deforms under heat, it is unfit for purpose.

Throw it back at the manufacturer and ask for some that's made from quality resin. The good stuff is about £1~£1.50/kg dearer than the cheap stuff. And how many kilos are in a full set of Locost mouldings? About £10 worth, at best.

Cheers,
Syd.


twybrow - 15/12/06 at 12:07 PM

Cost of resin has little to no relationship to shrinkage. Some resin mixes are more prone to shrinkage than others, but outperform in other areas. I assume the GRP is made from polyester resin (cheapest, readily available, easy to use etc). This is the worsst for shrinkage. On a car, the engine and heat will help to 'post cure' your part (if the manufacturer hasn't already), but remember on a car it is supported so should resist significant movement. Tg has more of an effect on brittleness and rigidity.

Best bet is support it, leave it cool and dark until it is fixed in place and if it warps then send it back.


Syd Bridge - 15/12/06 at 07:27 PM

quote:
Originally posted by twybrow
Cost of resin has little to no relationship to shrinkage. Some resin mixes are more prone to shrinkage than others, but outperform in other areas. I assume the GRP is made from polyester resin (cheapest, readily available, easy to use etc). This is the worsst for shrinkage. On a car, the engine and heat will help to 'post cure' your part (if the manufacturer hasn't already), but remember on a car it is supported so should resist significant movement. Tg has more of an effect on brittleness and rigidity.

Best bet is support it, leave it cool and dark until it is fixed in place and if it warps then send it back.


Shrinkage is usually in direct relationship to styrene content. The more styrene, the greater shrinkage, the cheaper the resin.

Post Cure?? Usually reserved for epoxies and like. How many manufacturers even know what it means? I use a high end poly that benefits from post cure, and it is twice the cost of the cheaper useable stuff.

Tg...You better get your manufacturers spec sheets out to learn more about the relative importance this has. As I said, Tg is the point it changes from hard to soft, so can then deform.

If you want to know more, I've been doing this stuff for more than 40 years!!!Look to the left for further clues.

Cheers,
Syd.


twybrow - 19/12/06 at 12:56 PM

Saying you have been doing it for 40 years menas nothing to me. Otherwise all 'experpienced' memebers of society would be experts in their field - this is not the case. You can do the same thing for forty years and still be rubbish at it (I am not saaying this applies to you, i don't know you)....

Post curing is used to increase the cross linking of the resin system, which can have the advantage of increasing the Tg. so whilst you are saying Tg is the be all and end all property, i am saying there are factors which affect Tg which can play a significant part.

As previously stated, Tg has an effect on rigidity and brittleness - it is the point a plastic changes to a glass (in terms of physical behaviour). A plastic will typically deform and return to its original shape. Glass will not.


Syd Bridge - 19/12/06 at 07:38 PM

I'll defer to your obviously far greater knowledge. Even though that same knowledge contradicts accepted norms in the composites industry.

You'd better write some new text books, as you seem to have made discoveries which overturn years of modern teaching.

And my engineering degrees and more mean nothing, in the presence such hallowed intelligence!

Cheers,
Syd.

I was working with carbon fibres in R&D in 1974!!!Helicopter blades. Built a cfrp skiff in 1975, and masts in 1976. Rudders and shafts in 78/79, and racecars in 80/81. Then I got serious!
That enough 'experience' in my forty years at it?

[Edited on 19/12/06 by Syd Bridge]


scotty g - 19/12/06 at 08:40 PM

good God, stop it the pair of you!
Can we all agree that if the panels are left outside that they should be wrapped up, supported and as sheltered as possible.............PLEASE!


Syd Bridge - 19/12/06 at 08:58 PM

Sorry sir, won't do it again, promise.

Cheers,
Syd.


twybrow - 20/12/06 at 08:44 AM

Yes we definately can all agree on that! Leave it out of sunlight, supported and cool.

Syd - i dont know you so i wouldn't make any comment to that effect.... I am not re-writing anything, just trying to have a discussion with a fellow composites man.

Incidentaly is yous 'high end polyester' an isophthalic or ortho?


Syd Bridge - 20/12/06 at 09:15 AM


Promised not to say any more.

Cheers,
Syd.

And it's a modified iso.


emsfactory - 21/12/06 at 10:32 PM

enjoying this.


PaulBuz - 22/12/06 at 01:52 PM

Damn, is it finished? ...only just got back with the popcorn


Syd Bridge - 22/12/06 at 04:06 PM

Bad Luck!!!

Switch across to the thread in 'Chassis' regarding suggestions for the McBearen.

Cheers,
Syd.