Have you ever wondered what makes a paper hot cup? What is in a hot cup that isn’t in other types of paper cups?
Paper is an ideal cup insulator because of three of its properties. First, it is able to reduce the passage of air through a cup because of the wood fibers that trap the air. It also conducts less heat and finally, paper blocks the passage of light radiation so it further reduces the passage of heat through the cup.
Regular paper cups can hold warm to fairly hot drinks but when it gets piping hot, you will probably need a cup sleeve or better yet, a hot cup. Hot cups are specifically designed for greater heat retention. Think of it as a cup with double walls or layers in which air is trapped. Therefore, the heat does not transfer to the human hand. Some multi layered paper hot cups have a decorative and corrugated layer which allows for better insulation as well as an opportunity for branding or advertising.
In the beginning, hot cups were made by being glued together. Its waterproof property was then achieved by dropping a small amount of clay in the bottom of the cup. The cup was then spun at a high speed in order for the clay to travel up to the walls of the cup so that it could be water resistant. However, due to this process, the cup’s content reeked and tasted of cardboard. To remedy this, hot cup manufacturers have developed the technique of spraying both the inside and the outside of the cup with wax. Later on though, polyethylene (PE) was invented and it was used to cover the surface of the board. The coating used for cups varies for hot drinks and cold drinks. Some paper cup manufacturers use PLA or polylactic acid or polylactide, which is a renewable resource and a biodegradable bio-plastic coating, to coat paper cups. The use of PLA makes a paper cup more compostable and thus more eco-friendly.