Sorry if this is the wrong place for this but I'm going to be picking up a fleabay carbon frame (yada yada poor Chinese workmanship, shattered carbon, taking my life in my own hands, etc) , and I'd like to paint it so it's not just raw epoxy-ed CF.
Does anyone have any advice? Let's assume I know how to paint anything at all, but as for carbon fibre, presumably I'm to carefully sand it down with fine-grit paper to make it rough, but do I need a primer of any sort?
Also, any suggestions on to the best brands or formulations of paint to use? Afterwards I'd like to polish & seal it with some clearcoat as well, so same question but for clearcoat.
you just need to thoroughly scruff sand it. There should be a relatively thick clear coat layer. You are going to have opportunities to explore how thick it is if you are tapering out around broken sections and bonding in repairs. In any case scuff sand with scotchbrite, or fine sandpaper. Just make the surface go dull, as thoroughly as possible say 220. Then you are ready to go. It should require effort to go through the surface, if hand sanding. Be careful about any hard edges, sand up to them and complete that process before working the hard points. There are a lot of strategies for hard points, like going to different abrasives, foam backing, finer. Touch the hard points as little as possible. Always use fresh paper. As soon as the paper cuts differently change it. You may be able to use if for something else, but not this. Sounds counter intuitive, but dull paper has a number of hidden time bombs. First it doesn't do a good job. Next it is uneven usually, and you may find that if you shift to hard corners that is exactly when you find a fresh section and cut through.
You aren't painting carbon, you are painting whatever clear coat is on it, or you are painting the resin. You could probably paint it with just about anything from Fusion spray cans to auto or boat paints. Good paint jobs normally use primers. The schedule for yachts is about 6 mortgage sized slices. But I normally go direct to awlgrip, which is why they don't pay me the big bucks.
Brain, use polyurethane car paint, so find a shop in your area with the paint and get a pint, that will be enough paint. Get 1/4 gallon of reducer also (ask the guy because the paint and the reducer need to match). Pick a color from the catalogs because the guy wont sell you a single thing w/o having the color code. Ask the guy also that u want single stage base coat/clear coat. Red color is expensier than other colors, and white depending on the brand it wont be sold in pints, the reason for that is because the white have all the colors mixed (par say) and if the ammount is so little the red might take over and u will end up with light pink instead of white. while in a gallon is not a problem. Again all depends of the paint brand also.
Primer, if you dont have a spray gun and compressor, get 2 or 3 cans of something called u-pol primer, i would advise you to get it in white color, they have light grey also, the reason is that the color will get as good as the color of the primer, if the primer is dark the paint will tend to get darker. Sand the imperfections in the primer with a 600 grit wet sand paper. apply like two coats and you will be fine.
Now the paint, to paint get somethiing called preval sprayer, it is a spray gun that works with a can of compress air, get like 3 more of those compress air charges also. The sprayer will go for 10 bucks or so. Mix the paint 50 and 50 with the reducer/thinner and put it in the sprayer (follow the instructions how to use it), spray lightly coats of paint until u get the whole bike sort of ok with paint ok? and one extra wet coat.
Let it seat for one day or so, if you got runs u can fix them next day by sanding with 600 or 1000 wet sandpaper. At this point for sure the paint is not shiny.
Now the clear, get upol clear coat #1, it is a 1k clear coat paint with UV protection. Get like 2 cans. Read the instructions, shake it like crazy and i advice you to put it in hot water a little bit, it will make the paint to flow better. 2 light coats and 1 wet coat and let it dry, sand imperfections when dried and polish it with meguiars hand polishing compound after this step the paint job will get super shiny. If you want more shiny u can use tech wax from meguiars for example, this is good stuff.
Another way to paint, get the paint... get 1/4 of gallon of clear (hope the guys have, some stores do not sell 1/4 gallons) and the activator for the clear. When mixing the paint with the reducer, drop some clear into the paint. this will make the paint to shine right away and will get more color deepness depending of the color obviously.
It is not hard to paint but takes a lot of practice, specially when u do not have the talent for painting (my case), i ommited a lot of details ok? so please figure it out and do the home work because it is pretty easy to mess up a paint job big time if you do or mix stuff wrong. Cracks in the paint after a few hours, paint seperating from the substrate and many other thing. Runs and fisheyes are easy to fix just in case.