Q: I have some brake calipers that I powder coated, and I would like to add lettering then then add a clear powder coat and put in the oven and bake it. I would like to know of any material (vinyl, decal, or anything) that can withstand 400°F to be powder coated over.
A: This is a tricky proposition. First of all, PVC (vinyl) decals will not take 400°F, so they’re out. There are a number of materials used to make decals, and the table below provides type and heat resistance.
| Polymer Type | Synonyms | Heat Resistance (°F) |
| Polycarbonate | PolyCarb | 150 |
| Polyester | 250 | |
| Polyvinyl chloride | PVC, vinyl | 300 |
| Polyethylene terephthalate | PET | 360 |
| Polyimide | 1,000 |
For your application, I would consider PET or polyimide as the decal polymer. PET may be borderline for heat resistance, but you should be able to use a clear powder coating that can cure around 350°F and avoid exceeding the heat-resistance threshold.
Otherwise, you will have to use a polyimide-based decal, which easily outperforms all other decal materials for heat resistance. Polyimide tapes are regularly used as masking for powder-coated articles, so I can attest to their resistance to typical powder curing temperatures.
Preparing the surface for the decal and choosing a powder coating are also important considerations for the success of your project. The surface should be wiped clean with a good solvent. I recommend either denatured alcohol or acetone. Both are readily available at your house paint or DIY store.
I would recommend a low-temperature-cure polyester powder coating as your clearcoat. Epoxies discolor with heat, and polyurethanes have a tendency to outgas at thick films. Polyesters capable of low temperature (around 325-340°F) are very commonly available. These products have good heat resistance and can be applied at relatively thick films to give a high gloss with excellent distinctness of image. Please ensure that the coating is fully cured to make certain that it provides full durability performance.