Knowing which plastic dishes are dishwasher safe would be very useful.
Imagine you decide to have a field day. You pack plastic dishes to serve lunch, as they are safer for meals outside.
When the time comes, you go home. Tired already, the thought of washing the dishes is not the first thing that comes to mind. However, someone has to do it, and in your case, something can do it: the dishwasher.
You put the dishes in a dishwasher safe place, go for a swim and relax a bit. But when the washing session is over and you check the dishes, you notice that something is not quite right. The plastic dishes have lost their shape.
If this has already happened to you and you want to prevent it from happening again, you need to read this post.
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Dishwasher-safe plastic plates
Plastic plates are present in almost every home. They are ideal for serving food to our children, as well as for meals outside, as they are practically unbreakable.
When washing them in the dishwasher, it is advisable to place them on top, as far away from the heating element as possible. However, this does not work with all plastic dishes.
What happens is that such an appliance reaches high temperatures (up to 80 °C), which certain plastics cannot withstand. Thus, the important thing is to know if the material of which the plate is made can withstand high temperatures.
In general, the materials with which dishwasher-safe plastic dishes are made are
Polypropylene is a very hard, toxin-free thermoplastic, which is also used in food and beverage containers. This plastic has many applications, even in the automotive area.
Since they are thermoplastic, they become malleable when they reach certain temperatures. But don’t worry, this only happens at temperatures above 150°C.
According to the SPI (Society of Plastic Industries) coding system, it is number 5. This system classifies the types of resin or plastic used in packaging or dishes. The number 5 comes within a triangle inscribed on the bottom of the product.
Polycarbonate is a group of thermoplastics with a high degree of stiffness and high temperature resistance. It is used in the manufacture of plates, dishes, water bottles, etc. You can also find this plastic in CDs and many other products.
It can withstand up to 125 °C, so dishes made of this material can be put in the dishwasher without any problems. In addition, it can withstand low temperatures, down to -135 °C.
It can transmit light almost completely, which means it’s a transparent plastic. This, together with its high rigidity, makes it a viable alternative to glass. Of course, the transparency can be graduated according to the manufacturer, there are polycarbonate plates that are not transparent.
Melamine resin (MF)
Melamine is an organic compound, and when combined with formaldehyde, melamine resin is produced. It is resistant to high temperatures and is even self-extinguishing (it stops burning when the origin of the fire is eliminated). It is usually used in the manufacture of tableware, but you can also find it in slates, tiles, furniture, etc.
Melamine resin is a thermosetting plastic. Thermoset plastics are malleable at medium temperature when synthesized. But when they cool down, they take on a fixed structure. Even if you subject them to high temperatures, they won’t become malleable.
Melamine resin is rigid, with good resistance to abrasion and deformation under load.
Acrylic (PMMA) is a transparent thermoplastic, and you may know it as “Plexiglas”, its trade name. It can withstand high temperatures without melting, up to 160°C. In addition to being used in tableware, it is also used as a thermal insulator.
It stands out for its transparency, in fact it is the most transparent plastic. It lets in almost as much light as glass, but is 10 to 20 times stronger than glass.
Acrylic is less resistant to polycarbonate (PC), but has a high resistance against scratches. In fact, many bulletproof “glasses” are made from polycarbonate and a surface sheet of acrylic. This provides strength and a scratch-free surface.
What plastic dishes can’t you put in the dishwasher?
However, not all plastic dishes are made from the above materials. Especially disposable dishes, which are made of materials that are less resistant to high temperatures.
You should not put dishes made from this in the dishwasher:
Polyethylene Terephthalate (PET)
PET is a thermoplastic with a high resistance to wear and corrosion. It is widely used in the manufacture of all types of beverage containers: water bottles, soda bottles, etc. Although it is also used in the manufacture of disposable tableware and in the area of textiles.
It has a low glass transition temperature of approximately 75 °C. In other words, at that temperature the plastic becomes malleable. Thus, if you put a plate made of this material in the dishwasher, it will lose its shape.
In the SPI coding system it is identified by the number 1. You will notice a 1 inside a triangle on the bottom of dishes and containers made of PET.
Polystyrene (PS) is a thermoplastic also known as Styrofoam. It is used in the manufacture of tableware and disposable containers such as: plates, glasses, trays, etc. Its applications are endless, in its expanded form it is used as insulation.
It can be malleable at temperatures between 85 and 105 °C, depending on the mineral oil content. Therefore it is not recommended to put in the dishwasher any dish made with this material.
It is the #6 plastic according to the SPI coding system. Therefore, containers and other utensils made with this material should have a 6 inscribed at their base within a triangle.
However, at Monouso we have an extensive catalogue of reusable plastic plates. All of them are of high quality, and will not deform when you put them in the dishwasher.
So don’t forget to visit our catalogue and check out all our offers in dishwasher-safe plastic dishes.