I’ve done up to five layers of glass - a mix of 4 & 6 oz - and had no problems wetting it all out with RR epoxy. I’m sure it could be done w/UV PE.
One thing I think helps me: Pour on lots of resin and only move it around as far as I can while keeping a thick/deep pool, then let it soak all the way through… Once its all wetted out, the layers of glass seem to float, then I sqeege out the excess, leaving the cloth saturated and tight.
Surfthis and Ozzy are correct. 4 oz to mid rail 6 oz lap. For the reason mentioned by Ozzy.
I thought I was gonna get hammered on this one.
There is value in what everybody said, and everybody is correct to a degree. Like what Jim said is true. But for me, in a production environment, when speed and other stuff counts too, I put the 6 on the outside. I have had resin start gelling on me from working it too long trying to get 6oz worth of resin to push through the tight weave of the 4oz on top. If I had all day to work it, I would probably put the 4 on top. But separating layers with different batches of resin is weaker and heavier. Maybe not a lot, but enough to notice.
In the end, what works best for you is the best way for you.