Cotton thread vs Cotton covered polyester thread?

[theo]

Mercerised cotton thread or cotton covered polyester thread? (Looking to be able to garment dye).

Unsure what is best strength-wise for sewing garments? Is there problems with the cotton thread shrinking?

For use with domestic machine.

 

[Alan]

Garment dyeing adds an interesting wrinkle to that question since you need the thread to actually take the dye the same way the fabric does. That part is genuinely over my head technically but it makes sense why you're weighing the two so carefully before starting a project. What are you planning to sew?