|Can you see how the top two|
tiers are more thoroughly
felted than the rest?
(By the way, I'm of a liberal mindset in the ongoing debate between the correctness or incorrectness of the terms "felting" and "fulling" in terms of creating knitted fabric first, then applying heat and agitation. In other words, I don't care which term you use.)
The following things can affect the ability of a yarn to felt (or full, if you prefer):
- Whether or not a fiber has been bleached
- Color of fiber before dyeing (I've tested this and some darker natural colors of wool felt better than lighter ones, even if the fiber hasn't been bleached.)
- The breed of sheep from whence the fiber grew
- The way the yarn was spun
- The type and amount of dye used on a fiber
- The combination and amount of heat and agitation
- The gauge of the knitting
- The type of stitch pattern used
- The size of the object in question
There are more variables, but these are the ones I notice most and plan for when I'm designing. You can see why, with all the possible combinations listed here, the final appearance of a knitted, felted fabric might be a bit dicey in terms of consistency.
So, make sure you do some swatching and experimenting whenever you undertake a felted project, and look at the process as a bit of an adventure, because even with the best of planning, things can still take their own creative turn. Instead of dreading that eventuality, embrace it and make it part of your creative process.