Hi
Im working on making underside panels for my car.
These panels do take some beating both from the car beeing low and skidding on the asphalt/curbes and also alot of stone chips.

My plan is to have two layers off twaron and four of carbon (reason for this combination is to have enought material)
Since im new at this at least for the first parts i will use a wet layup and then vacuum to form the carbon after the mould.

If i use regular resin the part will be really stiff and i believe it will crack easily, and since the flexible resin is a bit more gel like i believe this is better.
But with the flexible resin the part will be soft and the panels are there both to direct air and shield the underside, so i want the part also to be stiff.

And here comes the question, once the part is made with standard resin, can i apply a final coating of flexible resin to have the gel like surface?

Since it is an underside part the finish do not have to be 100%

Example picture to show similar panels

I don't believe the EF80 resin works like this (EC staff, correct me if I'm wrong?). It is a high elongation resin, so it's elongation at break properties are substantially higher than a regular epoxy laminating resin. This will give it the flexibility. However looking at the Shore D hardness of the resin, which is the property that describes how hard the surface is, it's got a Shore D hardness of 85-90. If you compare that to EC's EL2 laminating resin, that has a Shore D hardness of 85-88. So the EF80 is potentially HARDER than a regular laminating resin, although realistically it would be much the same.

The EF80 flexible resin is probably too flexible for this purpose, used on its own ..

I would definitely make a part like this out of a Carbon/Kevlar mix .. I've made very nice "semi-flexible panels" by doing a regular infusion, using Twaron/kevlar mix, and applying a layer of the same by laminating it on top with EF80 .. That way you get "the best of both worlds"  The panels will not crack into smaller pieces, and they will be a bit more flexible than the same thickness without the laminated on EF80 layer.

I made Enduro bike mudguards and engine protection this way.  They are VERY strong!!!

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Dravis so i understood it right.
You created first the part with regular resin, and then you laminated one/two layers with the ef80?

With regards to what Hanaldo said, the intended use as a stone chip prevention is not possible since the hardness is basically the same.

To conclude i think the best way to do this is to use twaron only with regular resin.
Will 6layers be enough for this type of application?

Been a while since I've been here and just spotted this.  I made a front splitter from a mixture of resins as you suggest and I can confirm the EF80 is rather susceptible to stone chips.  It does give great flexibility but is not the best for your application.  I have seen people make things like arch liners from Kevlar with a polyurethane resin which were tough rather than soft so some searching into resins would be a good start.  The stock EL2 is pretty good and I have an undertray (VX220) made with this resin.  Admittedly it doesn't get much of a bashing but has been subjected to a little trip through the gravel

Thanks for the input.
Im after a "rally-grade" property since it may be used in racing as well.
So when i make this i want it as though as possible.