Carbon fiber finish

I'm new to composites. I've made a few carbon fiber plates by laying up fabric and epoxy resin between two pieces of MDF wood and wax paper, basically making a sandwich and then clamping the heck out of it to substitute for a vacuum.

The plates come out pretty good but don't have the "glossy" cosmetic appearance that I've seen on other CF parts. I care more about utility than cosmetics, but it couldn't hurt to have it look good. What are my options? I've heard you can use clear coat in a can as a final finish, but that it may peel off over time. I've also heard you can layup with polyester resin instead of epoxy, but it won't be as strong.

Cosmetics aside, does my epoxy finish need UV protection? The parts will see MAXIMUM one hour of sunlight per week, probably.

Thanks!

 

Have you considered using melamine faced chipboard?It gives a reasonably good finish,but not a super glossy finish.For the level of exposure you are contemplating UV will probably not be a problem.The super glossy carbon components often seen tend to have such a finish as a result of being lacquered.The clear lacquer normally used with base+clear car paint systems is often used.

 

I if you can layup over glass it will give a great finish...epoxy and polyester resin will discolor in UV so we always spray automotive clear polyurethane for protectection. The problem with visible CF parts are the pinholes and bubbles...for this we use black "Bondo" to fill before clearing. A company called ADTECH sells AdTech No. 17 in black ...basically black bondo. Good luck.

 

Your best tooling surface for a clear glossy finish to your CF plates will be glass (preferabley tempered) as stated. This will preclude the use of mechanical clamping force though. Most who use this method will infuse the resins into the fiber by vacuum.

Melamine will leave a slightly mottled finish as it's a painted surface to begin with but if you have the time and patience you can wet sand and polish your plates to the desired finish. You will have to protect your part from UV by clear coating (automotive type clear coats work well) or varnish. Both of these will probably require post finishing to acheive a truly glossy finish. Spraying on a clear coat afterwards will likely result in an orange peel affect and require wet sanding and polishing.

You do have the option of laying down your clear finish (clear gelcoat some of which have UV inhibitors) over the glass before you lay in your CF prior to infusion. This will require special attention to the preparation of your tooling surface with waxes and release agents. With that minimal UV exposure it's not really required anyways. Hardly worth the bother.

A few pics of the part and a description of the sizes involved might help. IMHO a resin infusion process will result in a superior part but for one-off projects it doesn't make much sense. Now, if you're going to make 100 then the investment in time and material savings is pretty wise.

Good luck.