Fair isle, Jacquard and intersia are all different techniques for colour pattern knitting. Hand knitters may be familiar with fair isle and intersia but maybe not jacquard, I don't think this technique is used in hand knitting but I may be wrong.
Fair isle -colour pattern knitting with the floats in the back
Jacquard - Colour pattern knitting that is double sided. One side is the pattern and the other is a dotty pattern
Both these technique's can be automated in production by simply programming the pattern into the knitting machine, much in the same way you would scan an image into the computer.
The knitting machine then simply select's the needle's needed and the machine knits always with two colours. Depending on how this is done this results in the unused colour being carried across or knitted across the back of the fabric. This has limitations in the colours, only two per line, and the length of float across the back.
However intarsia resolves these problems but comes with it's own. If you have ever knitted an intarsia pattern by hand then knitting it on a machine is not much different. Instead of using the machine to select the needles and control the yarn the user has to do this. In simple terms it means a picture, sometimes very complicated and with many colours can be re-created on a knitted fabric. I used this technique on the bf's wolf jumper, this was a simple pattern with three colours but a pain in the butt! Since then I have been noticing intarsia being used on many shop knits. I wondered how they translated this complicated and time consuming process into mass production, and below is the answer:
Stella's intarsia Jumper
This is a video of knitwear production including intarsia and below is a video of my intarsia in process. Notice the difference? I'm so much slower I know! I find it a nightmare keeping all my strands straight- I become obsessed with untangling them.
The video is in double time and I have cut out some bits but it shows me doing just three rows of work!
Just another little interesting video of knitwear production -