I don't understand something. When FMQ, the main problem is tension, right? So why wouldn't I use the same exact thread (heavier weight/vareigated, etc.) in the bobbin to help make tension more "the same." Also I want the back to look just as pronounced as the front -- why not? I like the quilting to pop (though I'm a newbie to FMQ) so I'm planning to use 28 weight variegated cotton. Is that too thick for the bobbin or something?

I use the same thread, because honestly I don't have the money to purchase more than one thread. I do know that it is nice to use a lighter weight in the bobbin because the bobbin will hold more thread and then last longer.

It's your quilt. You can do what you want. If that thickness works for you AND you can afford it - hey, go for it. I generally use the same (or similar) thread type in both top and bobbin, but not necessarily the same color.

When I do something special on top, I do a test piece and see which tension setting is best.

Using the same thread in the bobbin is fine!
I use thinner in the bobbin mainly because it goes further so there are less bobbin changes - important with quilting on a frame, as bobbin changes can be a pain in the you know what. I also like the thinner thread because it tends to 'disappear' into the fabric after washing. That way if I have a wobble or two, or three.... it doesn't really show.

i always use machine quilt thread on top and bobbin then someone told me it works better to use a lighter weight for the bobbin. so i tried that, just to see the difference, and there certainly was. i believe it depends on what your machine can handle. mine can handle heavy bobbin thread so i will continue to use that. practice with each and see what works for you.

Whether you use the same or a different thread is entirely up to you. If you have tension problems that are alleviated by using the same, then it makes sense to do that. If you don't have tension problems, you may make a design decision to use different colors or weights. There are reasons for going both directions.

Hand quilters ALWAYS use the same thread top and bottom. LOL

I don't have tension issues. That being said, I always use the same weight top and bottom. If I pick a 40 wt. thread to quilt with, I use the same in the bobbin. I only use cotton thread. I think the recommendations you've been listening to are for a thinner poly thread in the bobbin. Which I wouldn't do because I don't quilt with polyester typically.

[quote=dunster
Hand quilters ALWAYS use the same thread top and bottom. LOL[/quote]

you made a funny...ehhehehe :lol:

I use the same cotton thread top, bottom, AND piecing. Same colour, too.

I just used coats and clark in my bobbin and Essential thread on top for FMQ. worked fine.