I use the same thread in the bottom. I rewind empty pre-wound bobbins so I have matching when I need it.
It depends on how your bobbin tension is set. If it is set for the real slim embroidery bobbin thread, then you may have trouble with the other. I have two bobbin cases; one for the light thread and one for the heavier thread. That way, I don't have to make adjustments or get frustrated. Try a little sample and see what works for you. Your machine might be forgiving enough to run regular thread in the bobbin.
Use the same embroidery thread in the bobbin for FSL designs.I have used black overlocker or ordinary sewing thread in the bobbin when doing black ,navy or other dark colours in case the odd stitch from underneath comes up ,without any problems.Use white thread for light colours ,thus saving embroidery threads for the designs right side
Monica I do not know what your machine is but my Ellegante will not sew well with anything but embroidery thread or embroidery bobbin thread in the bobbin. I would use the same as my upper if I wanted the same color front and back;Lillian
I use the same embroidery thread.
I am considering purchasing some 60 wt embroidery thread from Madeira in a limited number of colors so I can use it for bobbins for FSL and very small lettering.
Marcelle
You might want to check the thread @ www.smartneedle.com it comes with a bobbin filled with each spool