I personally us Rayon because I like the superior sheen, but I understand that polyester is getting better all of the time. I don't use Rayon on anything that will be bleached, as it won't hold up for that. ;)

It depends on what you are using it on. Polyester is more colorfast, but rayon tends to have a prettier shine to it. Yes, polyester will stretch, but rayon will too. It is when thread doesn't stretch at all that you have a problem (it breaks!) and stretching thread shouldn't cause any noticible puckering in your embroidery. It would be the stretching of the fabric itself that causes the ripples and puckers.

well raels i use Brother, QA, or La Sarta (spotlights brand) all 100% polyester i do have airplane that someone got for me but that is Viscose rayon and i have not tried that yet. I have Birch varigated thread that is silco thread it is 100% cotton ive not used it yet though. So i have really only used polyester so far.* 4 u

From everything I have read, if the project will be washed, a lot polyester is best. Rayon has more sheen, but will fade with some washing procedures. Tomanpete

I use always polyester thread- maybe because it`s the only thread in our shop that I can buy.If I want rayon I had to order it.I have been told also that polyester stands more wash than rayon , so it`s better to use it in materials that will often be washed.

raels, I use both and never have a problem with puckering, I even use them both in the same project, still with no puckering problem. Hugs and flowers.

I mostly use rayon because that is more readily available in my area and has larger spool of thread here. But I have heard also what the others have said about the quality and washability.

i've done 100's of embroideries and found both work terrific, but rayon will bleach out even with powdered bleaches, other than that both look great.

raels I use polyester most of the time . I like the sheen that my thread has ( marathon.com ) Shamrocks all around .