Does it really matter
 

Does it really matter weather you use cotton or poly thread piecing and quilting your quilt? I've been using cotton thread on top and prewound poly bobbins. Is this wrong? And are the quilt police going to show up on my doorstep?

I use whatever I have handy that is the right color at the time. I have been quilting for at least 40 years. Unless you are making quilts to enter is some fancy completion I wouldn't worry about things like that.

I don't use poly thread because of the old days from the 70s. I guess since there are quilters who like the stuff that they must have improved the quality of the thread. I will just stick with my Mettler Silk wrapped thread. It has never given me any problems with using it since the 90s.

The poly will melt if you need to iron. I learned the hard way. Glad it was only on one block.

I use Poly ILY thread all the time for piecing. Thin and strong and I've never had it belt when ironing blocks. Comes in big cones so it is really affordable.

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*** I use whatever I have.
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You may be thinking of the "invisble" threads. I use Guterman's 100% polyester for everything and it never, ever melts I'm happy to say!

I prefer poly thread for my bobbins. I keep my iron on med heat and no problem with poly melting although I have never had quality poly melt when pressing seams using a hotter iron. I tried to melt a poly seam and it took much longer then I would ever leave an iron on the seam.
I mostly buy Superior poly threads and pre wound bobbins for piecing. Mettler thread is not silk wrapped, it's silk finished. No silk in the thread at all. Everything you want to know about thread is here: http://www.superiorthreads.com/education/

I don't do show. What I use is what I have on hand. I usually buy double or triple when it comes to the neutrals. I usually have 4-5 bobbins wound at a time of the neutrals. I also have 2 bobbin cases for each machine. I have the cases labeled for each machine.

Even award winning show quilts have been made/ quilted with polyester threads! If poly thread had been available when my grandmother was young she would have used it! It is stronger than cotton and colorfast.