Hey guys quick question. I’ve never cleared Kevlar before but assume it needs some type of prep to get the mold release off the surface. I usually sand into my carbon slightly to get some surface bonding but Kevlar I know frays and am afraid of damaging the surface.
Do I treat it like carbon and sand with like 320? Or do I just wipe with some acetone and call it a day?
Treat it like any other panel and follow the surface prep instructions on your clear coats TDS.
It’s your favorite stuff. Sunshield I’ll be spraying haha
Then yes, clean with Prepsol/MEK, sand with 320 until all the gloss is gone, clean again and you’re good to go!
Just make sure you stop sanding once the gloss is gone, you don’t need or want to go back all the way to the fibres.
Yeah this will be tricky. I’m using 3k Kevlar so it’s thinner then my usual stuff…
Thanks man!
It shouldn’t matter, with 320 on an infused panel you shouldn’t cut through to the fibres too quickly.
I’d recommend doing it dry if you can as well, you’ll see your progress better than wet sanding.
Ok good tip man!
I sanded with 320 dry and did what you said. However some of the Kevlar fibers started fraying which I didn’t think was a huge deal but apparently I guess it was because when I cleared they made my surface very rough looking. I laid down two full coats so will wet sand and see if they disappear.
Have you ever had that happen and what would you do? I am trying to avoid sanding again with 320 and clearing but that may be my only option.
I’ve never tried it but someone told me you can wave a torch over the fiber and melt/burn it away.
Man. I wish I knew this before I cleared, haha.
You will need to re-clear it.
I’ve never had any luck with the torch method, I always found it either just curled the fibres into little balls or it damaged the fibres underneath the fraying.
I hate working with Kevlar cosmetically, it’s a pain in the ass just structurally!
Basically if I sand again with 320 the fibers that are sticking up will fray again and i’ll back at stage 1.
Will the torch’s method work with this?
AHh that’s what I thought.
What else would you recommend? Do I sand again with 320?
Will the strands standing up fray again?
Wet-sand it this time.
The fibres that had frayed will likely fray up again, but they should eventually come away, and you’ve now got a decent layer of Duratec on there to prevent rubbing into any more fibres. If they aren’t coming away and you’re worried about digging a flat spot, try use a razor blade to carefully slice the stubborn fibres off, then sand it again.
Man this is a nightmare haha. It doesn’t help that they are semi large parts too.
I’ll wetsand and give it another try. Should I use less aggressive sandpaper like 400? Does that have anything to do with the fibers fraying?
No, with Duratec you really shouldn’t go finer than 320, I’d have concerns about the adhesion if you did. It should in actual fact be sprayed over 180, so 320 is as fine as I would go.
Depending on how many fibres you have in patches. You can use super glue or cyanoacrylate glues to fill fibres before you wet sand. Peferably THIN CA. This makes the fibres hard and stiff so they snap when you go back over then with 320.
I’ve done this many times on smaller parts and it works very very well.
Just thought it might help in this situation.
Cheers
Tim
Sanding with 220 worked and I hit only a few small patches. Going to reclear tomorrow. Thanks guys.
Great tip!
Never sand Kevlar, if you can avoid it. It is a very tough fiber so the fibers get pulled out of the surface rather than sanded off, creating fuzz. It isn’t till you get to 1200 grit before fiber snagging stops. The torch trick can work but requires careful technique to not cause damage. Kevlar is used for fireproof garments. The concept is that the intense heat of a flame will degrade the tiny filaments sticking out of the surface before the solid surface is damaged. Then 1200 grit sanding is still required.