3 October 2018
Okay, I'm getting up on my soap box.
That said, when knitting a gauge swatch, DON'T cast-on the number of stitches that should give you 4". You CANNOT determine the gauge from a wrinkled piece of material with no margins. You need a clear area of knitting to measure without trying to 'tame' the edges.
You should cast-on at least 12 to 20 more stitches than you would have for a 4" area and knit at least 6" vertically.
So, if you are to get a gauge of 20 sts to 4 inches (5 sts/inch) then cast on 30 to 32 stitches and knit for 6".
If your gauge isn't working then DON'T ravel the yarn. Knit two rows to put a garter ridge across your knitting, change your needle size and keep on knitting. Now you can compare what is happening when you change the needle size.
What ever you do, DON'T ravel out your gauge and immediately re-knit a gauge using the same yarn. You've stretched out the yarn by knitting it and your gauge will not be accurate.
Now I'm stepping off my soap box. Thank you for reading my rant.