Tuesday, July 19, 2011

Knitting Math 7 - cables, ribs, dropped stitches, lace and bobbles

When you're doing your knitting math, there's always the possibility that you're working with a pattern with measurements that don't work out to the gauge math.  The listed stitch gauge multiplied by the listed inches does not even out at all.  What if you want to modify the original design?  Change its size or overall looseness?  Grrrr!
Ribs and Cables - very contracted!
Brioche Rib, a big contractor

Don't panic.  Does your pattern contain cables, ribs, dropped stitches, lace or bobbles?  If none of these are represented in the suggested gauge swatch, you've probably found your problem.  (If this isn't it, it may be "ease", covered in the next article.) 

Shrinkers - ribs and cables both contract your knitting horizontally when they're verticle, and cables will also contract it a little vertically.  Twisted stitches are also in this category.  When you're ribbing horizontally (like garter stitch, or any combo of right-side knit rows alternated with right-side purl rows) it will contract your knitting vertically. 

Growers - dropped stitches, lace and bobbles all cause the knitting to grow.  Dropped stitches create wide, elegant ladders of open work, and are the stitch that expands your knitting the most horizontally.  Lace will expand it horizontally, and usually expand it even more vertically.  Bobbles, because they disrupt the tension of the rest of the row, will usually expand the row horizontally just a little.

How do you know how much these decorative elements have affected the stitch count?  Ah, I think we all know the answer, we just want to avoid it.  Yep.  You have to swatch it.

After you achieve correct gauge on your basic swatch you need to make a separate swatch with the design element.  Use the needles that gave you gauge.  For your first row:

Make an 8 stitch moss stitch border, then an inch of stockinette, then a full repeat of the design element.  Then repeat the inch of stockinette and 8 stitch moss stitch border.  One row completed.

Keep following the pattern for the design element until you've finished one repeat of it vertically, or for four verticall inches of knitting, whichever is longer.  Now, measure your swatch at its narrowest and widest points, excluding the first and last two rows. Just like you would any other swatch, launder it the way you will launder the garment, and block it.  Measure again.**  Now you have a pretty good idea of what affect the design element will have on the measurements.

Our demo numbers:  Gauge is 6 stitches per inch, design element is 10 stitches per inch. The design element is one inch wide. Our total stitches inches in the row are 106, and total inches are 17.

If your design element occurs once, the math is this:  Total inches - design element (in inches) = inches in regular gauge.  If you need to make adjustment, make it in the regular gauge stitches, and make it match left to right unless you want something off

17 - 1 = 16  I have 16 inches where I can make an adjustment without messing with my design element. 

If your design element occurs more than once:  Total inches - (design element number of repeats x design element in inches) = inches in regular gauge.

If my design element occurs 6 times, 17 - 6 = 11.  I have 11 inches where I can make my adjustment. 

**Why do you need to measure twice?  Because how your garment will lay and measure after laundering and blocking is often very different from how it knits up.  If you don't measure it twice, you won't know how much it will grow or shrink, and you may end up making the wrong size by mistake.

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