Wednesday, June 12, 2013

Calculating the shrinkage of shrink plastic

Here's a little quickie for you...  I'm in the middle of a project that uses shrink plastic and this is a neat trick I found for calculating the shrinkage of my shrink plastic. 

The brand that I'm currently using says that it shrinks to 20% of its original size, but I wanted an easier way of working out what size of shrink plastic I need to start with.  Not all brands shrink at the same rate and a 20% shrinkage is a comparison of area.  It does not mean that the length and width measurements shrink to 20% of their original size.

With a ruler, I drew a line close to the edge of my plastic and then marked on the line each cm up to 5cm. (As you can see, I did it twice to show the comparison of before and after.)

I then shrank one of my little 5cm rulers in the oven and the 5cm measurement shrank down to 2.05cm.

5 divided by 2.05 = 2.439

Therefore, if I know how big I want my final shrink plastic shape to be, I just need to multiply the length and width of my design by 2.439 to find out the size of shrink plastic I need to start with. OR, simply increase the measurements by 243.9%

This method is really useful when, like my current project, your final piece needs to be an exact size - or thereabout anyway.

Here's a sneak preview of one of the things coming up soon... 5 Brownie points for guessing what it might be!


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kelleejm76 said...

This is such a smart but simple way to figure this out! Especially since it seems that different companies or even types will shrink more or less. Thanks for sharing :)

Grenouille Greetings said...

Thank you, Kathryn! I want to shrink a printed image to a specific size and I therefore need to calculate exactly how large to print my image. You came up with the perfect solution here in 2014 and 5 years later, I'm about to try it! I'm very grateful that you made the decision to post this! Crafty hugs, Lesley

Anonymous said...

Wow this was really helpful. Creative way to test it I need this exact idea I'm so glad I came upon it thank you for sharing

Anonymous said...

You're so clever! Thanks for the help

lisa b said...

Wow you wrote this in 2013!

It's now 2024! and I'm just about to do this, thank you so much for your solution to my problem!