Do You Have a Carbon Fiber Laminate with Pinholes?

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Have you ever seen pinholes in a piece of carbon fiber laminate? Pinholes are minor cosmetic imperfections that sometimes occur in gloss panels; they don’t affect the structural characteristics or strength of product. They look just like they sound – like a pin was stuck in the sheet. A sheet can have one or two, they can be clustered in one spot, or all over the sheet. They’re not noticeable from a distance but if you hold a sheet under a bright light and look closely, you can see them. They can be an issue for any manufacturer making carbon fiber laminates using a vacuum infusion technique.

What Causes Pinholes?

Pinholes occur as a result of the gases formed during the catalytic reaction between epoxy resin and hardener. In ideal circumstances, the outgassing from the reaction is completed when the resin is introduced to the carbon, producing a perfect high gloss panel without pinholes. However, circumstances can occur in which the chemical reaction not completed when the resin is introduced into the carbon and outgassing continues while the resin is being infused. When this happens, the gas bubbles are trapped on the mold surface and form pinholes.

What If I Have Pinholes?

Maybe it won’t matter for your application – no one will see them. If appearance is important, one common fix is to apply a layer of clearcoat to the sheet – it will fill in the pinholes and they’ll disappear.

Either way, if you’ve purchased a carbon fiber laminate that has pinholes, talk to your supplier about it. We inspect every piece of carbon fiber before it leaves our shop; we don’t ship product with pinholes. Some carbon fiber manufacturers view pinholes as an acceptable part of panel manufacturing, we don’t share that view. To us, they're second quality.

Questions? Comments? Write to us at info@protechcomposites.com.