How should carbon fiber fabric and prepreg be stored, and how long do they keep?

Dry carbon fiber fabric is easy to store: a dry, ventilated room at 10–35 °C with relative humidity below 70% keeps it usable for 24 months^[1][2]. Prepreg is different. Its resin is already mixed in and slowly cures, so it has to be kept sealed in a freezer and used within months^[3][4].

How do I store dry carbon fiber fabric?

• Keep rolls in their sealed, moisture-proof cartons until you use them^[5].
• Store them indoors, dry and ventilated, at 10–35 °C and below 70% relative humidity^[1].
• Keep them away from direct sunlight and heat sources^[1].
• Do not stack cartons higher than the limit printed on the packaging.
• Use older stock first.

How long does dry fabric keep?

The shelf life is 24 months. After that, the fabric can still be used if retesting shows it still meets its specification^[2].

How do I store prepreg?

• Put it in a freezer as soon as it arrives, in its sealed bag, below 0 °C. −18 °C is recommended, with humidity below 70%^[3].
• At −18 °C it keeps 6 to 12 months. At 0 °C it keeps 3 to 6 months. At 22–25 °C it keeps only 20 days to 1 month. The exact figures depend on the resin system^[4].

How do I use prepreg after it leaves the freezer?

1. Leave it in the sealed bag at room temperature for at least 8 hours, until no condensation forms on the bag. Opening it cold lets moisture condense on the resin^[6].
2. Lay up at 20–25 °C and 40–70% relative humidity^[7].
3. Reseal any leftover material and put it back in the freezer^[7].

What does this mean for ordering?

Order dry fabric in the quantity that suits your price and freight. Order prepreg only in the quantity you can use within its shelf life, and only if you have freezer space. If you have no freezer, dry fabric with your own resin is usually the safer choice.

Check the full specifications on the carbon fiber fabric and prepreg pages, then ask for a quote through the quote form.

Sources

1. Storage: Dry, ventilated room at 10–35 °C and relative humidity below 70%, kept sealed, away from direct sunlight and heat
2. Shelf life: 24 months; usable after that if retesting shows it still meets spec
3. Storage: Sealed, in a freezer below 0 °C (−18 °C recommended), humidity below 70%
4. Shelf life: 20 days to 1 month at 22–25 °C; 3–6 months at 0 °C; 6–12 months at −18 °C, depending on the resin system
5. Packing: Sealed, moisture-proof cartons
6. Thawing: At least 8 hours at room temperature in the sealed bag, until no condensation forms on the bag
7. Working conditions: 20–25 °C, 40–70% relative humidity; reseal leftovers and return them to the freezer