Knitting and Crocheting double stranded?

Question

What does knitting or crocheting double stranded do? What benefit does it have? Can you follow the pattern and not do double strands, just use a bulkier yarn?

Answer 1

Double stranding is useful for adding color in the pattern (using 2 different colors) or texture.  By using bulkier yarn, you lose the texture or mix of colors the pattern is trying to achieve.  Of course, you can do as you wish with the pattern, after all it is your piece.  Just, if you single strand it, make sure the swatch matches what the pattern is calling for or you will end up with something odd in comparison to the pattern.

Answer 2

Yes, you can switch one strand of yarn (if you use the heavier ply yarn) for 2 strands.

The up side of using two strands for your project is if one happens to break the other strand will keep the item from getting a hole and wearing out.

Answer 3

I agree that two strands can add color and texture to your knitting.  Two strands of the same yarn, though, usually just look like one strand of thicker yarn.  Two strands of the same yarn will usually gauge up at about 70% of a single strand or 70% of the average of the gauge of the two strands added together if using two different yarns.  

Example  with two strands the of same yarn, each with a stated ball band of 20 stitches to 4 inches - 70% is 14 stitches to 4 inches and this should be your approximate gauge to get a suitable piece of knitting - it requires some trial and error with needle sizes.

Example with two different size strands of yarn,  a worsted weight at 19 stitches to 4 inches and a bulky at 16 stitches to 4 inches.  Add 19+16=35.  Divide 35 by 2 = 17.5.  Multiply this result by 0.7 to get 70% = 12.25 stitches to 4 inches.  

These calculations give approximate gauges and gauge swatches are always needed.  Gauge swatches should be big enough to get an idea of the drape of the fabric, not just a tiny little square of knitting.

Benefits include being able to knit a wider variety of yarns, use up thin yarns, create custom combinations, add texture and color, and fun experimentin with knitting.

Yes, one thicker yarn can be substitutes if it's the appropriate weight to get the gauge.

Answer 4

Chunky or bulky weight yarn can be substituted for a doubled strand of worsted weight; worsted can be substituted for a double strand of sport; and DK can substitute for a double strand of fingering (baby or sock) weight yarns.  Other than color blending, if you want to substitute, just swatch and measure for gauge first to ensure that your substitute meets that measurement so the finished item fits correctly.