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What? Interfacing shrinks? I’m totally shocked to discover that not only does it shrink, but it shrinks A LOT!

In a follow-up test using the same non-iron interfacing, I thought I would try what I sometimes do with fabric that needs pre-shrinking but I don’t have time to wash and dry it – that is to iron it with a lot of steam instead.

In this test I’ve taken three identical pieces of interfacing cut along the grain and clearly marked them to identify them as well as notching them to re-align them after the test. None of these test pieces were prewashed as the test case is purely to see how the interfacing is affected by ironing.

Piece number one is the control piece and left as is for comparison purposes.

The second piece I ironed without any steam on a fairly hot iron. I pressed the piece of interfacing very well at least three times. Set aside to cool down.

The third and final piece of interfacing was heavily steamed and pressed using a steam generator iron. Whilst ironing you could tell it was shrinking as it changed shape wherever the iron was placed. I did this at least three times and then again without steam to make sure it was dry. Once cool, I was ready to make my comparison.

Take a look at the photos – unwashed interfacing is at the bottom and the washed interfacing on top. It’s absolutely clear that it has shrunk a huge amount and the implications on a dress shirt and the small pieces needed when cutting out collars and cuffs makes it clear why you have excess fabric after washing your garment.

This is piece number 2 on top of the control piece for easy comparison. You can clearly see the dry ironed interfacing has shrunk in the length.

This is piece number 3 on top of the control piece. Again, the shrinkage is clearly visible.

This image shows the side notches of The control and piece 3 which are no longer aligned. This demonstrates the shrinkage in the ironed version.

Closeup of the amount of shrinkage in piece 3 – the steam iron test.

In this image I have the control piece on the bottom with piece number 2 in the middle piece number 3 on top. Again, you can clearly see the differences.

In conclusion, I can confirm that using an iron on your interfacing will shrink it but more so using steam rather than just dry. This variation in shrinkage is not ideal as you run the risk of having different pieces of your garment shrink at different rates and therefore distort your fabric. I found that using steam in large volumes shrank the interfacing the same amount as washing and steam ironing (see previous test). This is a great discovery as it will remove one step in the process – washing.

Please note that my test was performed using a steam generator iron. If you are going to try this using a small domestic iron, it produces much lower volumes of steam and you will therefore need to run a similar test for yourself to ensure your interfacing has shrunk fully. In addition, this method can only be used for sew in interfacing – you’ve been warned! 😀

This was a test well worth spending a bit of time on. It has taught me to check shrinkage on all interfacing and never use it without pre-shrinking. I hope to find that my latest batch of dress shirt collars and cuffs will be smooth and bubble free for their entire lifespan.

Happy sewing. Stay safe and well

Michele Nel MBE

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What? Interfacing shrinks? I’m totally shocked to discover that not only does it shrink, but it shrinks A LOT!

Why am I suddenly concerned about interfacing? Well, after making hubby dozens of dress shirts I am increasingly annoyed by the changes to collars and cuffs after a couple of washes. Some bubble, some appear to have excess fabric and finally, they don’t remain the stiffness that the collars require.

It was because of the bubbling mainly that I moved to non-fusible interfacing. I had assumed it was inferior quality (even though I only buy top brands for his shirts) but it turns out to be because it shrinks at a different rate to the fabric. I may therefore have to rethink this.

After the time and attention it takes to make a dress shirt, this is extremely upsetting. Testing was necessary.

Here is my test….take your sew-in interfacing and cut it into two identical sizes keeping the grain the same on both pieces. I cut a notch in them to realign after washing.

Wash one test piece in hot but not boiling water.….I did this by hand using my handmade laundry soap bar.

Allow to dry.

Iron and compare.

A few notes about interfacing in general that we’ve all possibly heard…Non-woven interfacing has no direction of grain and you can place your pieces however you want. I don’t prewash it because it doesn’t need it and the instructions don’t tell me to. The weight stays the same and is stable.

I need to debunk ALL of the above following my test!

Take a look at the photos – unwashed interfacing is at the bottom and the washed interfacing on top. It’s absolutely clear that it has shrunk a huge amount and the implications on a dress shirt and the small pieces needed when cutting out collars and cuffs makes it clear why you have excess fabric after washing your garment.

In addition, the interfacing has only shrunk in the length and not the width. If you don’t place your pattern pieces squarely on grain, then you will have twisting in your garment as well.

Finally, the washed interfacing has lost a fair amount of its stiffness. Not as big an issue as the others but, this explains why after washing the shirts the collars, cuffs and collar stand are a bit too limp. I’m going to have to either buy an even heavier weight or try doubling up this one.

In conclusion, I can 100% confirm that washing your interfacing is essential. Keeping your pattern pieces on grain is essential even with non-woven – be careful with this as many interfacings don’t have selvedges as a guide so perhaps mark the grain. The weight and feel of the finished collars etc will change – factor this in when choosing which interfacing to use for your particular project.

I hope that my testing; even though only on one brand, has helped you as much as it has helped and educated me. You see, even after 50 years of sewing I’m still learning – a lot!

Happy sewing. Stay safe and well

Michele

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My #bonnybay mandala throw is complete.

I had so much fun making this with the variety of stitches and I’ve already started on her other crochet blanket pattern.

Her YouTube channel is brilliant and has step by step video tutorials to guide you through the entire pattern.