Cardboard, known as paperboard, was a long-time visor ingredient in vintage baseball caps. Economical and easy to use, the earliest baseball caps were all made with some variation of this material. It’s also handy to note that many reissues or heritage reproductions of prior historical caps now almost always use plastic, for the benefits of durability.

Most baseball cap manufacturers now use plastic visors made from high-density polyethylene (HDPE). The visors are die-cut into the shape using flat sheets of this plastic. Curved brims are then heat-molded into shape. Some manufacturers use a ‘foamed’ plastic visor. This is done by putting a little bit of air into the material to create a hard foam. This can be more cost-effective than using pure plastic. This foamed version still has the same water-resistant qualities as the un-foamed plastic visors. 

The last category is the one now favoured by New Era. It’s referred to as a resin fibre blend. This is a mix of plastic and cardboard, and it provides the best properties of both. The cardboard fibre gives it a bit more softness, flexibility, and shape memory, whilst the plastic provides the toughness and durability that you get from a plastic visor. This has been used frequently in New Era's caps for over 20 years. 

How to know what visor material is in your baseball cap.

Now that you know about the different materials, how can you tell what's visor materials are used in your cap collection? Here are a few ways that you can tell. 

Feel

The feel of the visor is a major indicator. Give your cap a slight flex and see how it reacts. If it's plastic it's going to spring back fairly quickly to any flexing movements. By comparison, cardboard is going to 'give' a lot quicker and may not be so resilient in springing back to shape.

Shape memory

The second thing to look for is the shape memory of the material. Doug and I have found that with plastic visors, you need to flex them before each time you wear them.

Despite steam curving it, plastic tends to lose its shape faster over time, in comparison to the plastic fiber blend.

The mixed visor retains the shape a lot better than the pure plastic one. I find it always tries to spring back to its flat condition.

Brand

You can also tell by the brand of the baseball cap. As previously mentioned, New Era has been using the plastic and fibre blend for 20 plus years. It seems that other brands have followed suit. 47 Brand, Mitchell and Ness, Supreme all use some variation of a plastic visor.

Even vintage baseball cap manufacturer Ebbets Field Flannels mainly use plastic. The only caps that they produce with cardboard visors are the limited soft visor range, which is clearly labeled.

The standard New Era plastic and cardboard blend doesn’t spring back as forcefully as plastic does. You don’t have to steam this visor quite as long as you would a pure plastic visor.
  
47 Brand’s plastic visor has a sharper sound when you tap on it. It will also spring back a little bit more forcefully when you try and flex it. The pure plastic visor has a higher softening temperature – you can leave them in the steam just a few seconds longer than a standard New Era cap.

A completely soft visor, as shown in the gif, makes a dull sound when you tap it. You can see by how easily its cardboard visor flexes and moves around.

Cleaning cap visors

As mentioned before, you don’t want to soak or submerge the visor even if you know for sure it's all plastic or the plastic fibre blend.

Because the visor is the most handled and exposed area of the cap, this often gets dirty very quickly. It's okay to consider using a fabric protectant on the visor. This will help to stop water from penetrating the visor. It will also make it easier to clean.

Brushing is the best way to routinely keep your visor clean. Be sure to pay particular attention to the crevice between the visor and the crown of the cap. That tends to be a magnet for dirt and debris. 

How to steam curve your visor

If you like to wear your caps with a curve and the visor contains plastic, then it is recommended to always heat the visor with steam. Click here to see Doug’s curving video tutorial.

When the material is warm and pliable you're avoiding creating small or large cracks in the material. If you bend the visor whilst it’s cold, it fatigues the material and creates, a lot of cracks so over time. It will lose its stiffness and the ability to hold shape. In extreme cases the visor can snap completely.

Storage - How to protect your visors

Storing your baseball caps in a safe place is essential to keeping them in ready-to-wear condition, whether it's in bin storage, a cap carrier, or inside your closet on a shelf. The main goal is to keep it away from dust and accidental spillages.