Jun 20, 2025 · Preservation
Foil cards: curling/warping and what to expect
Foils love to curl. It’s not “you did something wrong”; it’s materials science. The good news: many curls can be improved. The bad news: aggressive DIY methods can permanently damage surfaces, edges, or the foil layer.
Why foils curl
Curling is usually driven by humidity and how different layers expand/contract. Foil layers and paper layers respond differently to moisture, creating tension. That tension shows up as a curve.
What “good” flattening looks like
- Gradual: improvements over time, not instant results.
- Controlled: stable humidity/temperature and gentle pressure.
- Reversible mindset: we avoid methods that permanently change the card’s surface.
What to avoid (common mistakes)
Don’t
- Apply high heat (hair dryers, ovens, heat guns).
- Use excessive clamping pressure on edges/corners.
- Press directly against rough surfaces.
- Leave foils in humid rooms (basements) long term.
Do
- Store in a stable, dry environment.
- Use appropriate sleeves/holders.
- Flatten gradually and check frequently.
- Prioritize surface safety over speed.
How to keep foils flatter long-term
- Control humidity: aim for a stable, moderate environment (avoid swings).
- Use rigid storage: semi-rigids/toploaders help reduce re-curling.
- Avoid heat sources: windowsills, heaters, and hot cars.
- Check periodically: early curl is easier to correct than severe curl.