How to do a Shrinkage Test

Posted by Kathleen Fasanella on Nov 16, 2007 at 12:54 pm / Textiles and Inputs / Trackback

I asked Jennifer Ennis to write a guest entry to elaborate on the comment she made under How to calculate denim shrinkage as a guest entry because a site search doesn’t return results from comments (Timo’s comment was also useful). She agreed and this is the result. Thanks Jenn!
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How to do a Shrinkage Test
Here’s a little bit of a write up on how to perform a Shrink Test. It’s good for either garment washed – i.e. denim or testing home laundry conditions.

Supplies:

  • It is best to create a good template for marking so that you’re not measuring out squares over and over again – preferably made from acrylic with a handle on one side to make it easier to hold. Or you can purchase a template from testing supply house.
  • If you are using light colored fabrics, you can use a permanent marker like a “Sharpie”. If you’re testing a dark colour, look for metallic “Artline Markers”. If you’re washing with chemicals like enzymes or acids (for wash effects) do a test wash to see if the marking stays. There are also paint pens which cost $15 apiece but sharpies and artline markers are cheaper.


The process:

  1. Draw a square on the fabric with interior dimensions of 12.5 inches aligned to the warp of the fabric with a permanent marker. Make sure the lines are dark and even in thickness.
  2. Mark the warp direction with an arrow
  3. If doing multiple squares across (good), number the squares and record these on your chart
  4. Wash and dry the fabric
  5. Do not press or iron the fabric, this will change the dimensions (you can do a separate test for pressing too, a good idea for dry clean only)
  6. Measure the square in the weft direction in at least three places, from inside the line on one side to the inside of the line on the other side and record each measurement
  7. Repeat measuring for the wrap (weft) direction

Calculation: (1/8″ equals .125”)
The easiest rule of thumb to remember is that for every 1/8″ the lines shrink, this equals one percent in shrinkage.

  • Ex. Before wash, the lines measured 12.5 inches so if the fabric measures 12 3/8″ after wash, the difference is 1/8 or 1% shrinkage calculated as .125/12.5=0.01 x 100 = 1%
  • Ex: If the fabric measures 12 1/4 inches after wash, the difference is 2/8 or 2% shrinkage, calculated as .250/12.5=0.02 x 100 = 2%
  • Because each 1/8″ less in line length equals one percent of fabric shrinkage, the lines are drawn (pre-wash) to the specific length of 12.5″ to make math calculations unnecessary.

Below is a sample chart I recreated from memory that I used at a local garment manufacturer (full size).

The details one should record are standard, such as

  • Fabric name (i.e. Black Streaky)
  • Fabric code (CCBS11)
  • Fiber content (i.e. 100% Cotton)
  • Fabric supplier or source (Arvind Mills Ltd)
  • Date
  • Tester’s name
  • Batch or lot number (of the fabric)
  • Colour (Denim)
  • Wash details
    • water temp
    • duration
    • chemicals used (enzyme, detergents, bleach etc..)
    • dry temp and duration

Also see the previous entry Materials testing #17659/17801 which include full size forms with these details.

[Amended}
Jennifer forwards two additional thoughts:

  1. If you are going to doing 5 home laundries, add columns to the table and keep remeasureing the same fabric. It’s usually a good idea to touch up the lines if they start to fade (common if drawn in metallic marker).
  2. Cut 3 inches away from the lines if you’re cutting it out of your production header. This allows for raveling.

8 Responses to “How to do a Shrinkage Test”

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Mariana
March 16th, 2012
7:07 AM

Great post! Demystifies this process and makes it doable for any technician.

anna
November 24th, 2013
11:44 PM

hi, im a fashion student. Can you explain how to calculate this for a garment? for example. the hps to hem of a s/s top is 30″. But the fabric test was actually 12.5″ x 12.5″? and lets say it shrunk 8% in length and 0% in width. How would i come up with the correct formula?

Andrea
January 29th, 2014
4:40 AM

Forgive me this possibly stupid question but there’s something i don’t understand about all this matter of shrinkage. Why isn’t it done already when we buy the fabric , or if not then do it after buying it and before sewing it up.

The thing is, if a customer tries on a garment and it fits, aren’t you risking it not fitting so well after the customer washes it if it hasn’t been washed/shrunk beforehand.

Secondly how is fabric dyed so as shrinking does not occur causing this problem in the first place.

There’s obviously a problem with my thinking given that i’m worrying about it and you are not. Please help me understand why its not an issue to resolve before sewing. And how you deal with the matter of customers experience in the shop and after washing the garment.

Of course traditionally people new that jeans would shrink but its not something i give a second thought to with any other garment and i never wear jeans anymore anyway so never think about it when i buy something. I just don’t expect clothing i buy to shrink. And why should i? Why should my customers?

Kathleen
January 29th, 2014
3:38 PM

Hi Andrea, this isn’t a stupid question at all.

Yes there is a risk of customer fit dissatisfaction if shrinkage is not addressed. Ignoring shrinkage can be perilous to everyone -which is why we worry so much about it. It is a daily challenge. Here are some shrinkage posts previously published on this site:
Retailer’s rights to return defective products (shrinkage)
Why 5% shrinkage is fatal to a start up clothing line
Shrinkage and fit
Cutting trims and shrinkage
This is of course, in addition to what I’ve written in my book, what appears in the forum and all that. Shrinkage is often the over riding preoccupation in a pattern maker’s day.

There’s obviously a problem with my thinking given that i’m worrying about it and you are not.

I don’t know how you come to the conclusion that I am not concerned about shrinkage. If I weren’t concerned about it, I wouldn’t write about it. A google search shows that the term has come up on this site 338 times.

Secondly how is fabric dyed so as shrinking does not occur causing this problem in the first place.

Oh my, I’m not sure where to start. Textiles are based on natural products like cotton and wool. Cotton and wool shrink. The only way to keep textiles from shrinking is to go to the source and mess with the genetics of plants and animals so that they produce unshrinkable fibers.

As to “how is fabric dyed”… there are whole libraries and colleges -not just books-dedicated to the subject. To reduce it to the simplest equation, have you thought about how all this fabric can be dried? If you have a roll of fabric that is 1000 yards long (not unusual, some rolls are so heavy they must be lifted with special forklifts; some rolls weigh in excess of 6,000 lbs!), what kind of dryer can handle that? Assuming there were such a machine, how will these goods be pressed flat and rerolled? With today’s technology, it is not possible. Therefore, we have to test the goods we get and modify the pattern to adjust for the shrinkage in the fabric.

And how you deal with the matter of customers experience in the shop and after washing the garment.

There are 3 key ways to deal with it. Garment washing (this is discussed a lot in the forum), educating the customer with hang tags and lastly, requiring dry cleaning.

Of course traditionally people new that jeans would shrink but its not something i give a second thought to with any other garment and i never wear jeans anymore anyway so never think about it when i buy something. I just don’t expect clothing i buy to shrink. And why should i? Why should my customers?

I’m not sure I understand why you are so angry about this. I can’t change the laws of nature. You don’t think of shrinkage… that’s great. Me… it’s a consuming part of my day. I assume that anything I buy will shrink and purchase accordingly. If other consumers don’t… well, maybe someone needs to break it to them but I have the feeling they’ll find out one way or another. I get the sense that you think that somebody is avoiding their responsibilities and while I can’t say that is always false, I can say that I go to extraordinary ends to make sure that all of my designers keep this uppermost in mind and have a defined 1-2-3 list of steps to follow to manage the problem as efficiently and as cost effectively as possible.

Alison Cummins
January 30th, 2014
7:42 AM

how is fabric dyed

Interesting. I admit, when I think of dyeing I still think of vat dying. And when I think of vat dyeing I think hot water that will shrink the fabric. So you would think that I would imagine that dyed (as opposed to printed) fabric is all pre-shrunk.

Oddly enough, I don’t. I wash and dry all my fabric as soon as I get it home from the store. Even wool goes straight to the dry cleaner. I’ve never tried to reconcile my assumption of the pre-shrinking action of dyeing fabric with my action of pre-shrinking my fabric in the wash.

Huh.

Andrea
January 30th, 2014
7:32 PM

“I don’t know how you come to the conclusion that I am not concerned about shrinkage. If I weren’t concerned about it, I wouldn’t write about it.”

Only because i thought it would be easier to preshrink than do all those calculations.

I don’t know why you think i am angry at all about any of it? I am not in the least bit angry and i didn’t think anything in my questions suggested i was angry.

Ok i understand that you can’t preshrink a roll of 1000 metres. But do you think i should pre-shrink 30 metres? Is that the best way to handle it? It would be easier than all the calculations and fabric testing that have to be done and factored in for a smallish quantity of fabric. Though i can’t fit 30 metres in my machine. Perhaps i would have to cut it up a bit. I am not looking forward to any of that either. Well the ironing bit is what bothers me the most. Hanging on my line is easy. Its a very long clothesline. I think i will not iron until after cutting out the pattern. I hope that would work well enough.

Will washing ruin the fabric finish. One of my cottons has a sheen on it and its not sateen fabric. I had presumed that it would. Perhaps i should do a test wash on it.

Kathleen
January 31st, 2014
9:05 AM

But do you think i should pre-shrink 30 metres? Is that the best way to handle it? It would be easier than all the calculations and fabric testing that have to be done and factored in for a smallish quantity of fabric.

I can’t speak to the best way to pre-shrink 30 meters. Pre-washing that much yardage would not be my choice but then I have experience and resources that give me more or better options. I do know that people often start out with this proposition, trying to make it work, but it becomes more work than the alternatives. Sometimes one doesn’t realize how problematic this can be so I think it is a good thing to try it so you have a point of comparison. If you have more time than money, what’s the harm in trying it?

Will washing ruin the fabric finish. One of my cottons has a sheen on it and its not sateen fabric. I had presumed that it would. Perhaps i should do a test wash on it.

This speaks to the heart of textile testing. Imo, failing to do so is like playing Russian Roulette with your business. This subject (again) is covered more extensively in my book and other posts on this site (see links left previously).

Andrea
January 31st, 2014
2:41 PM

Thanks Kathleen.

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