About a month ago, a follower asked about what modern yarn to use for a vintage knitting project. My response to a baffling question was it is all about the gauge–but what also matter’s is the texture of the vintage piece and what you personal preferences are. Part 1 of this vintage interchangeable yarn guide provides you with the types of yarn by needle size, which has an effect on the finished gauge. Many yarns are interchangeable Define interchangeable – by interchangeable I mean that two yarns knitted or crocheted by the same person on needles or hooks the same size will have the same gauge (the same number of stitches to the inch (cm). The yarns may be quite different in texture, or they may be the same type of yarn from two different yarn companies. To prepare this resource, yarns were knitted or crocheted using basic stitches (i.e., stockinette/chain) the basic stitch. A suitable needle or hook size was used for each yarn. Yarns used with the same needles or hooks which were found to have the same gauge are arranged alphabetically in groups listed under the needle or hook size used and the gauge obtained. The hook/needle size and the gauge are not necessarily the same as those suggested in specific knitting or crochet directions. Just about every yarn can be crocheted or knitted on several needle or hook sizes and in many different pattern stitches, thus changing the gauge. In this guide, the yarns in each group may have different textures; they may be soft, smooth, rough, nubby, hairy, looped, or slubbed. The fiber content is noted with each yarn to help you choose the yarn which best suits your purpose. Care must be taken in substituting cotton, linen or metallic for wool since these fibers have less elasticity and added stitches are needed to obtain proper fit. Yarns Not Included Some yarns are omitted: yarns that do not interchange such as ribbons, too individual in their properties to be included. I will add another reference to discuss those properties. It is sometimes possible to substitute one yarn for another, even though the two yarns do not appear to be interchangeable, by changing the needle size. This is determined by crocheting or knitting a swatch in the substitute yarn to see if the proper gauge can be obtained and the texture is satisfactory. In any case, a swatch should always be made before starting a project. It is important to note that many factors contribute to variations in yardage, such as humidity, temperature, stretch and tension, also how the yarn is measured; therefore, our calculations are approximate and may vary considerably. Interchangeable Yarns List Needle/Hook Size 2 Needle Size 2 | 7 1/2 Stitches = 1″  Needle Size 2 | 7 Stitches = 1″ Needle Size 2 | 6 1/2 Stitches = 1″ Needle /Hook Size 3 Needle Size 3 | 8 Stitches = 1″    Needle Size 3 | 7 1/2 Stitches = 1″ Needle Size 3 | 7 Stitches = 1″ Needle Size 3 | 6 1/2 Stitches = 1″ Needle Size 3 | 6 Stitches = 1″ Needle Size 3 | 5 Stitches = 1″ We will end this section with needle and hook size 3, if you’re looking to substitute another type of yearn please post your question. Here’s another link that’s been around for awhile listing lots of vintage yarn types and you might find it helpful. http://www.vintageknits.com/vintyarn1.html Here’s a few free vintage pattern links where gauge is an important factor for success when knitting and crocheting patterns that you might want to test this new information. I would like to suggest that you enlarge the image that comes along with the pattern to see the texture and any characteristics of the  yarn that might effect the outcome of your piece. Free Vintage Patterns Vintage Knitting Pattern Book | The Fourth Day of Christmas Free Vintage Knitting Crochet Patterns for Dolls 6 to 17.5 inches Free Knitting Patterns Sheath Dresses Ensembles Suits – Vintage 60s Holiday Handknits Girls Boys Babies Toddlers Free Vintage Knitting Patterns Vintage Argyle Men’s 40’s Style Classic Sweaters https://blog.vintagepatternsdazespast.com/http:/blog.vintagepatternsdazespast.com/category-name/free-vintage-patterns/ If you prefer your patterns in PDF format to follow this link to my ETSY store.