Nance

Mettler thread is recommended by Bernina, I believe. I would not be afraid to useit.

lfletcher

I've used Mettler thread for piecing, applique and quilting. It's great! The right color is what is important to me.

nanna-up-north

Mettler is a perfectly good thread and the 50 size is what's recommended for sewing on a machine. Hand quilting is size 40. My LA thread is size 40. 40 is a thicker thread. So 50 is perfect for a DSM.

As far as using old thread, I do it all the time. I do remove the outer layer of thread from the spool and do a breakage test on it. I've had new thread break more easily than some of the very old thread on wooden spools so it really depends on the amount of time it's been exposed to the air and sunlight.

So, don't worry. That Mettler is just fine.

quilterpurpledog

Mettler is great thread! I use it frequently-right color. I have lots of older thread and use it all the time. Part of the question about thread deterioration can be environmental such as temperature, ultraviolet exposure and humidity. I live in a rather cool, dry climate and store my thread in a cabinet so I never worry about this. I have thread that is years old. The break test that you mentioned has several components-fiber content, number of plies, size of plies and amount of twist. If it breaks easily and multiple times in your machine then you should not use it. If it sews in nicely, then use it.

Mariposa

Mettler and Aurifil are two of my favorite threads to use. I say use them, and have fun!

Kelsie

I sewed a sample, only about 18" long but it didn't break. I also took a good look at it and there is no fading or discolouration. So glad as the colour is perfect for the backing. Cheers, Kelsie

QuiltnLady1

This is what I do as well and have had no issues.

Quilt30

If it easily breaks, then don’t use it. Older threads are still good to use. I continually use 60 year old thread.