The Magic Of Shrink Plastic: How Much Does It Really Shrink?

Shrink plastic is a versatile material that can be used for a variety of craft projects. When heated, it shrinks to a fraction of its original size, typically between 20% and 50%. The exact shrinkage rate depends on several factors, including the brand, the type of oven, temperature, and time spent heating. It's important to note that the shrinkage is a comparison of area, not the length and width measurements. This means that crafters must carefully calculate the size of the plastic they need to start with to achieve their desired final shape.

The shrinkage of shrink plastic varies by brand

One user tested the shrinkage of their plastic by drawing a line close to the edge of the plastic and marking each centimetre up to 5cm. They then shrank the plastic in the oven and found that the 5cm measurement shrank to 2.05cm. This means that the plastic shrank to 41% of its original size.

Another user found that their plastic shrank to approximately 45% of its original size. They also noted that the oven temperature will depend on the brand of shrink plastic, so it is important to check the instructions.

Shrink plastic shrinks in the oven

To calculate the shrinkage of your shrink plastic, you can use a ruler to measure the original size and then measure the size again after shrinking. For example, if you have a 5cm ruler and it shrinks to 2.05cm, you can divide 5 by 2.05 to get 2.439. This means that if you know the final size you want your shrink plastic to be, you can multiply the length and width of your design by 2.439 to find the original size you need to start with.

It's important to note that not all brands shrink at the same rate and that a percentage shrinkage is a comparison of area, not the length and width measurements. You can also use fine-grade sandpaper to lightly sand your plastic so that it holds colour better.

Shrink plastic can be flattened with a cake server or cardboard

Shrink plastic can be flattened with a cake server or a thick piece of cardboard. It's important to press down on the plastic while it's still hot, so be careful not to burn yourself.

The amount that shrink plastic shrinks depends on the brand. Some shrink to 20% of their original size, while others shrink to 45% or 50%. It's important to note that this is a comparison of area and not the length and width measurements. For example, if you start with a 5cm piece of plastic, it may shrink to 2.05cm. This means that to calculate the size of your final shape, you need to multiply the length and width of your design by the ratio of the original size to the shrunk size. In the example of 5cm shrinking to 2.05cm, you would multiply your length and width by 2.439.

The oven temperature and time will also affect how much the plastic shrinks, so it's important to follow the instructions for your specific brand.

Shrink plastic can be sanded with fine-grade sandpaper to hold colour better

Shrink plastic is a versatile material that can be used for various craft projects, from accessories to stamps. The amount of shrinkage can vary depending on the brand, oven type, temperature, and time. On average, shrink plastic shrinks to about 45-50% of its original size, so it's important to start with a larger design than the desired final size.

To enhance the colour adhesion and overall appearance of your shrink plastic creations, you can lightly sand the surface with fine-grade sandpaper before shrinking. This technique helps the plastic hold colour better and improves the final aesthetic. When sanding, it's important to use a light touch and move the sandpaper in irregular patterns to prevent deep scratches. Wet sanding is generally recommended to avoid scratching the plastic, and you can use a sanding sponge or foam block for better control.

The process of wet sanding involves immersing fine-grit sandpaper (between 180-600 grit) in water for about 10 minutes before use. You can then gently rub the sandpaper in a circular motion across the plastic surface. Alternatively, you can use dry sandpaper, but it's crucial to follow the same irregular sanding patterns to avoid deep scratches.

By sanding your shrink plastic before shrinking, you create a slightly roughened surface that improves colour adhesion. This simple step can make a significant difference in the final appearance of your project, ensuring that your chosen colours are vibrant and well-adhered. Remember to always work in a well-ventilated area when sanding and follow safety precautions, such as wearing a dust mask and protective eyewear.

The thickness of shrink plastic varies

All shrink film styles are .010” prior to baking, which is the thickness of a business card. The oven temperature will depend on the brand of shrink plastic you are using, so it is important to check the instructions. For example, one brand may recommend an oven temperature of 170 degrees.

It is important to note that the shrinkage of shrink plastic is a comparison of area, not length and width measurements. This means that the plastic will not shrink to 20% of its original size in length and width, but rather the overall area will be reduced by 20%.

To calculate the shrinkage of your shrink plastic, you can use a ruler to draw a line close to the edge of the plastic and mark each cm up to 5cm. Then, shrink the plastic in the oven and measure the new length. For example, if the 5cm line shrinks to 2.05cm, you can multiply the length and width of your design by 2.439 to find out the size before shrinking.

Frequently asked questions