Felted bag

[DutchOma]

I'm sure I have seen threads on felting before but cannot quite find what I'm looking for.
I want to make this bag and it's felted. Now I've already found out that you need pure wool for it which needs handwashing only and thought that I might just use some of the vast quantities of Shetland wool I have lying around. Use it double. But then? Do I just stick it in the washing wachine on a hot wash and hope it works? Or in hot water in the sink?
Any advice?

Oooh I make felt felt (as opposed to knit then felt). My mum bought me a kit for my birthday once, from one of those craft fairs.

It's very easy to do, but takes a while and a lot of effort! I generally make a piece which finishes up about the size of A4, then cut it up into smaller pieces to make cards (I use greens and blues, then make fish and boats out of copper wire and stick them on, IYSWIM).

I've done it! I used a swatch of Shetland knitting and swilled it around it soapflakes and near boiling water for half an hour, filling up with hot water from the tap.
Silly idiot that I am I apologised to the piece of knitting before I did it and still feel vaguely guilty.
BUT it did turn out as quite a different piece of stuff than what I began with.
It was 17cm x 11cm to begin with, now it is 15cm x 8cm, very fuzzy and quite firm.
It is now drying next to Gingermonkey's son's cardi which got washed in the same water after I had put lots of cold water with it.

I have now knitted up the bag and had a go at felting it. I swilled it through some hot soapy water for about half an hour but, although it has gone a bit fuzzy, the stitches are all still visible and it hasn't really gone felty.
What should I do?

1. Accept that this is what you get and do the embroidery?
2. Do some more soap and hot water?
3. Stick it in the machine with the next 40 degree wash?
4. Anything else?

really hot water (I just read something about it on a blog!!!). Boiling hot that burns your hands. ps, I like that bag a lot!