Yes it's best to use a stainless steel pot, but if you are using alum anyway then an aluminium one won't make any changes. Copper and iron would also act like mordants if used as pots. I am lucky to have an old Baby Burco boiler which my Dad used to use to sterilise the shells of the turkey eggs before they went into the giant incubators. It's great as you can dye a big load, enough for a whole jumper, in one go, and you don't need an external heat source. But they are difficult to get hold of. Stainless steel dog bowls are good for small quantities, but ss itself is so cheap these days that you can pick up a big stockpot for not very much, or buy yourself a new one for the kitchen and use the old one for dyeing
(as with pressure cookers - great idea
) .
If you like multi coloured yarns, fairly simple ones can be made by dipping only part of the skein into the dyepot for one colour, then once the whole dye process has been copmpleted, dye the other end with a different colour, and if you let the two meet in the middle you will get a third colour. For example I have used green and blue, to give green, blue and turquoise,stormy summer sky colours, and I have used light green and light purple to give green, purple and deep purple, which when knitted up looks like a heather hillside
. The length of skein you use partly governs the repeat you get. A way to get spotty yarn is to dye the whole lot in the basic colour, then wind it into a ball and sit the ball in a shallow amount of a different colour and cook it for an hour (this is for chemical dyes). Again with chemical dyes you can get random colours by wetting and laying the yarn in a baking tin, then dripping different dyes over the yarn. Oddly they don't run together very much so you get some fine colours. The yarn on my website was dyed using that method, dyeing each singles separately then plying them together after they were dry.