how does the shrink factor work?
Making sure your work felts to the right size.
After felting, the gap between the fibres has reduced, making the fabric denser and reducing the overall size of each swatch. The fibres also become much softer and colourwork patterns are gently blended. The ‘shrink factor’ is also a key aspect of felting, and crochet fabrics usually tend to shrink more widthways than they do lengthways because of the larger gap between the stitches than the rows.
Calculating the amount that your fabric shrinks is vital to being able to crochet an item that will measure a certain size after felting, and swatching is a vital part of this process. Let’s take our swatch worked with a 10mm hook as an example – it has 10 sts and 12 rows to 13cm square before felting. After felting, it’s 10cm wide and 11cm high. To calculate the shrink factor, work as follows: Measurement after felting (10cm) divided by measurement before felting (13cm) = Shrink factor (0.77). You can use the shrink factor to work out how big your item will be after felting. For example, you’ve made a rug 145cm square, so work 145 multiplied by 0.77 = 112cm after felting.
You can also use the shrink factor to work out how big to crochet your item to achieve a specific measurement after felting. For example, suppose you want a felt hat that’s 60cm circumference, so work 60 divided by 0.77 = 78cm. So you will need to crochet the hat to 78cm circumference. Then use the swatch to calculate how many stitches you need to achieve that 78cm, by working: Desired size (78) divided by Swatch size (13) = Stitch ratio (6). Stitch ratio (6) multiplied by Stitches in the swatch (10) = Stitches needed (60). You’d therefore need to crochet 60 stitches for your hat.