I’m doing a carbon fiber lay up and I have a problem with the contours. The fabric seems to lift up after I applied the first layer of resin.
Anybody have some techniques or products for this issue? I’m currently using the applying resin on the plug and wait until it becomes tacky to apply the fabric method.
Post a pic of the part. If you’re just overlaying the part you may have to do it in steps “like do one section at a time” if you don’t have access to a bagging system.
http://shop.mercedes-benzofmiltonkeynes.co.uk/catalog/images/A2046802391.jpg
It’s the cup holders cover in in the picture. The fabric on left and right sides start to life up when the resin is going to B stage. I also tried using super 77 today and the fabric lifted up too. Did I do something wrong?
Like the cup holder cover where it’s on the cup itself? The black ring
Or the lid that I see that slides where the cup holders are.
If it’s the ring on top of the cup itself that will be a hard part to overlay unless you have some kind bagging system.
If it’s the lid that’s the sliding part on the console you shouldn’t have any problem other than the added thickness of the material/epoxy you’re using so it could cause an issue with being able to open and close it.
It’s the black cover that the slide sticks onto. On the flat surface I don’t have a problem, but contours are giving me the headache, I know it’s not supposed to be an issue, but I don’t know why the fabric lifted. Could it be the basecoat that I apply on the plug is too thick or I leave it to too long and the tackiness starts to cure rather than holding the fabric?
I’m still not exactly sure what part you’re talking about in the picture so maybe circling it would help. Sorry it’s been a LONG week to say the least.
It could be a number of factors but I’d say yeah either the initial layer of epoxy you let tack was to thick but I’m wondering maybe it could be something else. These are the steps I always followed while hand overlaying parts.
- Scuff up surface real good, 60 or 80 grit works well, along with razor blade cross cutting sections
- Drill very small holes “1/32” drill bit I think around the parts edges every few inches and maybe 1/4 away from the edges. These act almost as rivets I was taught so when the resin drips over to the other side it will fill the hole and then loop around the back. I know it’s not ideal but its better than just overlaying.
- Wash part with some kind of degreasing soap. I used to use rubbing alcohol but I switched to dawn soap.
- Let part dry, it needs to be completely dry
- Put on gloves
- Cut your fabric
- Mix your resin “try not to get air bubbles inside”
- Put resin on part and on a test piece of something, like cardboard
- Wait until it tacks up real good so that you put your finger on there and hardly anything comes off, if any I’d say. DON’T touch the part with your finger, touch the test piece, or at least keep the gloves on if you touch the part. The main reason for gloves is to keep the oil and grime from your hands off your fabric and part
- I used to tape down edges around the backside if I had hard time getting parts to sit, but now I use a bagging system.
- This next step is up for debate if anything. Sometimes I wait until the first layer and fabric completely cure, and sometimes I put a THIN layer of epoxy over the part while the first layer isn’t all cured yet. I like to think the thin layer will bond better to the epoxy.
- Normal steps of building up and sanding down…
All I can say though is wait for the epoxy to tack, and I wouldn’t use spray adhesive. Just keep in mind it’s a car item, cars get hot so your part needs to have solid contact since it’s going to go threw many temperature cycles in it’s lifetime. You have the heat working against you, and also the part you’re overlaying is plastic, and nothing I’ve ever used likes to stick to plastic…
Thanks 
That’s quite informative. I’ll give that a try. I think I missed out the step 10 that I should tape down edges around backside. Should I wait til the first coat to cure and lightly sand it down then apply subsequent coats or build the layers and sand down?
I never sand until I get a few coats on in fear of breaking into the weave.
The only reason you’ll have to sand epoxy between layers is to even it out, or because you have air bubbles and you want them to go away before you build more layers on.
The earliest I actually sand the resin is after the fabric is down and cured, and another layer is on. If I have air bubbles I do a light scuff to pop them, if not then I build more layers and wait.
I think it also depends on the resin you’re using as well. Some cure differently than others meaning some will cure flatter or more “wavy” than others. So sanding a lot depends on the user/resin.
I see. Last question, when do you think is the best time to trim the piece?
That depends. I trim in Stages because the epoxy I use and have only used doesn’t lay down real flat so I ten to trim in the beginning stages, and then later down the road as well from minor drips and such. If you don’t have a dremel invest into one with a carbide cutting wheel
thank so much:)