I'm looking at lots of different types of patterns and they say very specific brands of yarn to use for the pattern- so does that mean that the pattern is designed only for that specific yarn? If not, then how do I know how to find a yarn that is the same style or type as the one used in a pattern?
Hi erin, the most important thing to lookat on a pattern is the guage. That will basically tell you how 'thick' of a yarn to use. It shows you how many rows and how many stitchs per square in (or some multiple of 1 square inch) you should have.
Almost every skein of yarn will have its guage listed on it...so all you need to do is find one that matches the guage listed in the pattern, or comes extremely close. If its close enough, you can probably knit out a guage swatch, and determine if you ahve to go up or down a needle size to compensate.
Another thing you can do is bring the pattern to a local yarn shop...any individual working there should be able to show you what weight yarn you need to use if you are going to substitute.
Something else to consider is the drape of the yarn based on the material you use. say the yarn called for is a 100% wool yarn, if you choose something that is of a different material, the garment could come out lookign somewhat different. For example, a wool bamboo blend will look more 'drapey' when finished...as will silk blends. Sometimes that is a look you might be going for, sometimes its not.
Anyway, check out the guage on the pattern. If the pattern does not give the guage, look up the specific yarn called for online. It should give you the details, including the guage of that yarn...or at the very least the weight of the yarn (lace, sport, fingering, worsted, aran, bluky etc.)...then all you need to do is pick a yarn of the same weight.