The material that guitar picks are made from can affect the tone as well as how comfortable they are to hold. There are some wild and wonderful materials used nowadays, but we’ve covered the main ones here. It’s also worth noting these are generalisations – some players will have a naturally brighter or warmer sound due to the way they play and where they strike the string.
Delrin
Delrin picks tends to give a fairly bright tone and a strong attack. It depends on the gauge, but they’re quite rigid too. You can also find coated options, like the Dunlop Tortex range, which helps them grip a little easier, otherwise they're quite smooth under the fingers.
Nylon
Nylon picks will usually yield a slightly warmer tone with a strong attack. When used in a certain way, you almost get a little compression while digging into the notes.
Ultex
Ultex picks are usually very stiff and rigid which leads to a bright and snappy tone. Even thinner gauge ultex picks can feel thicker than they actually are.
Celluloid & casein
Celluloid picks became more popular after the ban of tortoiseshell in the 1970s and they aim to replicate the warmth these picks produce. They’re fairly smooth so there isn’t much to grip on to but many players use them without dropping them. Casein picks get even closer to the sound and feel of tortoiseshell.