Needle Size
Needle packaging often implies that the weight of the fabric you are sewing dictates your needle size. I.e. the lighter the fabric, the smaller the needle size, and the heavier the fabric, the larger the needle size. There is some truth to this, if you are working with a delicate fabric you probably don’t want to use a huge needle. But the reality in quilting, where you are mostly working in cotton, is that your needle size is driven more by the type of thread you are using. Specifically thread weight.
Now to be honest, after writing about thread weight in my Picking Out Thread (Quilting) post, I had hoped that I would never have to talk about thread weight ever again. Researching thread weight was THAT painful. Unfortunately, it is difficult to have a conversation about needle size without bringing it up.
The rule of thumb is that the lower your thread weight (and thicker it is), the bigger the needle you will want to use. When using 50 wt. cotton thread, Jacquie Gering in Walk recommends a 80/12 needle. Ashley Nickels in Free-Motion Quilting 101 agrees, however she also mentions that for a finer cotton thread like 50 wt. Aurifil, a 70/10 needle might be more appropriate.
Needle Type
There are different types of needles. My quilting books don’t discuss this topic much and I’m not sure why. Perhaps like many things in quilting, needles are a very personal choice. Based on my research, if you want to try to pick needles to use for quilting, here are your main options:
quilting needle (not to be confused with hand quilting needles) - slightly rounded needle that can pass through multiple layers of fabric and can also be used for piecing
universal needle - slightly rounded needle, general purpose
sharps (now known as microtex) needle - sharp needle, can be used with high thread count fabric as it pierces the fabric, rather than pass through it
top stitch needle - sharp needle with a double sized eye, used with heavier fabrics and/or heavier threads. Superior Threads has a video on this needle.
Again, there is no one advice fits all when it comes to needle types for quilting. You may want to pick up some different types initially to try out, and figure out what works for you.
How Often Should You Replace Needles?
There isn’t a standard answer to how often you should change out the needle on your machine but I’ve seen estimates as low as after 5 hours of continuous sewing, and as high as after 8 hours of continuous sewing. Everyone does universally agree though that sewing with a dull needle is bad news. Your machine has to work harder at piercing the fabric, you fabric can get damaged, your stitches can skip, etc. Considering how inexpensive needles are, its an easy investment you can make into your machine and sewing project. If you are like me and wondering how to dispose of sewing needles, there are some ideas here. Personally, I think using a sharps container is probably the best method, although I’m guessing the tape method is probably easiest for most people.
15-91 Needles
15-91 machines use class 15 needles (i.e. 15x1 Needles or Singer 2020 needles). This is a very common type of needle and can be found on other machines (this can be attributed to Singer’s early dominance of the sewing machine world).