Originally Posted by
mbake
I'm confused now about what needle size to use. I have a long arm and was using a size 16 until someone at my local quilt shop said I should be using a 18.....So, I am using an 18 on this quilt that has the white poking through. I guess I'll go back to a 16 to see if that also helps. Thanks.
Your needle size is COMPLETELY dependent on your thread. Your thread is what determines what size needle you should be using. Here is a helpful guide from Superior threads for their threads.
http://www.superiorthreads.com/reference-guides/
Click the link that says "Longarm machines thread reference guide" For our domestic machine members, use this same link only click "Home Machines thread reference guide"
You can somewhat figure out for other brands based on fiber content, ply and weight. But not always. Some thread manufacturers will tell you what size needle. Others you sometimes have to experiment. For example, Superior's Magnifico is a 40wt trilobal poly. Same as Glide thread. Superior recommends running a size 18 needle for Magnifico, I usually run a size 14 for glide. So sometimes you have to experiment. I try to use the smallest needle size the thread will allow. If your thread starts shredding and breaking a lot, you know you have to go to a bigger needle.