I use RA Rayon on everything and have no problems with it.I have even put it on kids clothes with no problems of it fading.I like the sheen to it.
Well elaine u got your answer, I use both & u do have more sheen with the rayon but I must confess I prefer poly. *4U
Sorry Mary, but I should clarify, it (supposedly) does not stand up to heavy laundering so it is recommended not to use it on anything that needs frequent washing.
I keep my Rayon Threads for Picture type embroidery, 'special occasion' linen, ie. Christmas cloths and napkins, etc. and as Mary says, it is wonderful for FSL designs.
Hope this helps.
hnr, Meganne