I'm not sure of the safety of the clear threads, but poly is much nicer than the nylon. Another thought, if you get s thinner thread, it will "blend" in more with your fabrics. I'd go for at least a 50 weight and would even consider Invisifil 100 weight. What kind of thread were you sampling with your colors? I have a multi color chevron ready to go. I am going to use a variegated thread on the colored parts and a very light variegated on the white parts. I unrolled a bit and tried it on many of the colors and think I will be happy with it.