Long arm tension issues with one spool
 

I am quilting a throw on my longarm. There's a red border, green border & white snowmen. We decided to use 3 colors of thread, red, green & white with matching bobbin thread. When I was all done and unrolling the quilt, I noticed that in the areas using the green thread, there were eyelashes on the back that Maybelline would be proud of. I mean most were 1/16", some were 1/8". It actually looked fine from the front. The areas quilted with red and white were just fine.

All 3 spools were the same brand, same type, same weight and actually purchased the same day. Bobbins all wound the same time with the same bobbin winder. I quilted the red, cut the thread & rethreaded with the green, cut & loaded the white, then green again etc. I know the machine was threaded exactly the same because I cut the thread at the spool, attach the new color and pull the new one thru. Each time I changed the bobbin thread, I checked the tension doing a pull test and everything seemed just fine with all three colors. I made no tension adjustment on the bobbin or the top and used the same needle thru out.

I guess the upside is it's really easy to take the stitching out, and I caught it before I unpinned it from the frame.

Never thought to do a test with each color. I guess I will do that in the future. All I can think of is that the green was thinner than the other colors, so the top tension was looser?? (but the bobbin tension seemed the same for all colors)?? Has this happened to anyone else?

I've had thread tension on my la [gammill classic+] only when I've forgotten to 'floss' the thread thru the tension. I would swear it went thru there just like it was suppose to, and it looked like it was suppose to, but it didn't behave lit it should have done.
You can try pressing on the bobbin thread and see if it feels like the other bobbins, ie: not spongy or hard like a rock.
Just glad you caught it before unpinning!

I think the chemicals required for certain colors can change the qualities of the thread.

I had terrible problems when I 1st started quilting on a short arm system with a spool of varigated blue thread. I did SO want to use something pretty! Some spools just wont play nice!

if you thread by cutting the thread, adding new & pulling it through...sometimes the 'new' thread does not make it through the tension disks completely- its important to pull on both sides of the thread around the disks & make sure the thread is in there correctly- this can make such a difference= you 'know' everything is done right...but the thread is actually laying on top of the tension disk's instead of being between them-so not getting the tension correct on top---which would cause problems on the bottom.

This is what I think was happening. It is a really dark forest green, and I know the really dark colors have so much dye that it can make them a bit stiffer. I'm going to do some testing without resetting the upper tension disks, but making sure that the thread is firmly seated. This should verify that it was operator error (or not).

Thanks everyone for your replies!

make sure you post your results! 90% of the time I change top threads by cutting old, tying cut end to new and pulling through. But I do test tension between each change because I did know that dyes can affect thread thickness/quality even in the same brand due to saturation needed.

The last time I had something like this happen to me though, it was because a little blob of lint was caught in the bobbin case causing the bobbin tension to be much tighter than what I had set it at. It is so infuriating to have to take out all those stitches and redo. But you are right, it is really easy to frog them when the tension is off!

Yes, check tension when changing colors of thread by sewing a bit on a scrap sandwich....I make my own w/ muslin,batt,muslin and serge around edges....I always check stitches when changing thread color...and yes, dark colors are more prone to cause a tension change(top).....but needless to say a nano-speck of LINT can really be the cause of so many messes!!!!!! I clean bobbin and bobbin area with each bobbin change or thread change......

I have found it best to check tension on scrap at the side with all thread changes.