I have been "skinning" and doing hand layup and Infusion for maybe 10 years now, and my conclusion is solid:  Skinning and getting really good results is NOT worth the effort if you have a part you can make a mould from and infuse the part .. out comes a REAL carbon fibre product, lighter and stronger than the "original" - the work needed to make the plug, the mould and doing an infusion is much more satisfying than skinning.

Succesfull skinning is like doing a really top end paint job, painstaking attention to cleaning and degreasing, sanding and polishing.  "soft and flexible parts are a bi*** to do, and you NEED a dry and warm room to work and cure the parts in. AND the room needs to be clean and free of dust .. Timing the B-stage of covers is essential, get it just slightly wrong and you loose adherence or mess up the surface of the first layer.




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Hey guys, 

I'm still fighting the fight with the spoiler, so here is an update following the long weekend. 

But first few general comments in response to some member posts:

The reason I'm doing the project was purely for aesthetics, I was looking for a car spoiler of a certain size and could only find it available in ABS plastic. Being the DIY kind, I took inspiration from videos I've seen on YT, and decided it was worth a shot. I did sand the ABS with 80 grit and keyed the surface aggressively before starting. This is actually the second layer of CF that I've put on the spoiler, since I ended up damaging the fabric on the first when i was sanding the piece down. So I sanded the epoxy and restarted when I rewrapped the piece again.

Regarding Steve's comment about making a mould, I did think about it, but given my success with the project so far, it seems that the skills needed to do that are greater than what I've been able to master so far. Let me know if not the car. 

Regarding the thermal expansion issue, I'm pretty sure that the bubbles formed when the piece was exposed to the hot sun a couple weeks ago. Since I'm doing this for aesthetics, I'm not going to try to get down to the ABS to try to reattach the fabric to the plastic. Maybe some relief cuts in the fabric would be sufficient. Other recommendations are welcome. 

Now onto the update;

Put another 2-3 hours move sanding the piece down to remove more of what seems to be a bad top layer of resin. On a positive note there seems to be a clearer layer of resin below it, but I'm getting awefully close to hitting the fabric as I've already seen some black sanding dust near the edge with the more visible weave:



At one point, we had a sudden bout of rain and the piece got wet again. It looked like winter arrived again with all the snow:



Fortunately, it the snow effect is very superficial and it can easily be sanded away. 

Question for the group:

At this stage, would you guys top coat with a new layer of resin or would you keep sanding, knowing that there is risk of damaging the fabric? Not sure if the new layer of resin would lock-in the bad layer below it, or if adhesion problems might migrate to the top coat. 

Thanks

Fasta is correct about covering plastics. ABS is particularly hard to stick too. 80 grit will give you a fighting chance.

+x

 

Fasta - 9/1/2018 10:15:27 AM

I agree start again.

I have never had any luck getting rid of the moisture whitening, temperatures during cure must be dry and 20C +.

To help things stay stuck you could drill many 1-2mm holes through the plastic to provide and real key for the resin to grab and prevent any releasing.

Personally I don't skin plastic parts, usually the resins will not stick anyway and you will also be fighting against the thermal issues of the plastic and carbon. Most plastics expand considerably with heat wheres carbon fibre will not expand at all so any heat will always be tempting this to release.

Welcome to the world of composites.

I would never skin an object as I can't see the point other than for questionable aesthetics (as I paint all my carbon to disguise it I am slightly biased :-) ).

If after a CF wing why not make a mould and produce a real CF one? However,  if you are only looking for the CF look then why not simply vinyl wrap the wing? Alternatively, get it hydro dipped.

I agree start again.

I have never had any luck getting rid of the moisture whitening, temperatures during cure must be dry and 20C +.

To help things stay stuck you could drill many 1-2mm holes through the plastic to provide and real key for the resin to grab and prevent any releasing.

Personally I don't skin plastic parts, usually the resins will not stick anyway and you will also be fighting against the thermal issues of the plastic and carbon. Most plastics expand considerably with heat wheres carbon fibre will not expand at all so any heat will always be tempting this to release.

Welcome to the world of composites.

Hi. I’ve don’t have the experience that others on here have but I think I would cut my losses and sand back the C/F bubbles to the ABS. If it’s not stuck at this stage it never will. Then fill and sand the resultant low area and start all over again taking great care to have a clean and grease free surface. Mix your resin very thoroughly, the bubbles could be unmixed resin. ( try the two pot method to ensure the mix is free of any unmixed pockets of resin or hardener in the corners.

Been there, produced the scrap, got the T shirt. Best of luck mate. Keep at it. It’s worth all the effort when the result matches the expectation and remember that if it was easy anybody could do it.

+x

 

Telram - 8/31/2018 11:51:07 PM

Hey guys 

Sorry for the delay, I've been a little down from the results and haven't worked on this as quickly as I would have liked to.

That said, here is an two topic update:

1) So I kept sanding through to get through more of what seems to be a bad layer of resin. In some area the top layer seems to be scaling off, and the  boundary between layers seems to be apparent. 


I'm not sure how aggressive I should be with the top layer, on close inspection post sanding, the snow is still very visible. But when wet the snow disappears.




Also, when I run my finger vigourously against the wet resin, the resin seems to roll up like dead skin would.


At this point, I'm wondering if I keep sanding and take more of the top layer of resin off or if I go ahead and top coat with a fresh coat of resin. Part of me is worried that I will hit the CF later.

Thoughts?

2) After I left the piece in the sun for a day, the CF fabric pulled away from the spoiler in 3 bubbles. I can actually push the bubbles in to force them back against the ABS plastic, but they just pop back up. I've sanded around them and the tops now have small holes. 


I'm wondering if I should just pour some resin in there and just support the now bubbled fabric in place. What do you guys think?

Thanks
T

Hey guys 

Sorry for the delay, I've been a little down from the results and haven't worked on this as quickly as I would have liked to.

That said, here is an two topic update:

1) So I kept sanding through to get through more of what seems to be a bad layer of resin. In some area the top layer seems to be scaling off, and the  boundary between layers seems to be apparent. 


I'm not sure how aggressive I should be with the top layer, on close inspection post sanding, the snow is still very visible. But when wet the snow disappears.




Also, when I run my finger vigourously against the wet resin, the resin seems to roll up like dead skin would.


At this point, I'm wondering if I keep sanding and take more of the top layer of resin off or if I go ahead and top coat with a fresh coat of resin. Part of me is worried that I will hit the CF later.

Thoughts?

2) After I left the piece in the sun for a day, the CF fabric pulled away from the spoiler in 3 bubbles. I can actually push the bubbles in to force them back against the ABS plastic, but they just pop back up. I've sanded around them and the tops now have small holes. 


I'm wondering if I should just pour some resin in there and just support the now bubbled fabric in place. What do you guys think?

Thanks
T

any update?