White vinyl is the DEBIL!!! Do you want the teacher lecture why?
Tough, here it is:
It’s equal parts chemistry, physics, and optics. White vinyl has no dye additive which means straight white vinyl lacks some of the polymers that make other vinyls less floppy, squishy, deformy. Meaning white vinyl, no matter the maker, is going to be more floppy, squishy, deformy than other colors no matter what.
That floppy, squishy, deformy, is going to lead to more push/pull effects when stitched on. And because the human eye is particularly well adapted to pick up light (in this case white behind darker stitching) we SEE the white MORE and BETTER “behind” the stitches than on any other color.
So how do we “fix” this.
Step 1 – does it REALLY have to be TRUE white vinyl? Can you get away with like beige or buttercream or maybe even a white irid (because the irid polymers will cut down on the floppy, squishy, deformy)?
Okay, no, it HAS to be TRUE plain ole white vinyl.
Okay, fine. 1) stabilize the frack out of it. Project calls for medium weight? Screw that use HEAVY weight cutaway. Hell, use TWO pieces of heavy weight. Maybe even use some spray basting just to REALLY STICK it in place.
2) Cant the vinyl at a 45 degree angle. The substrate on the back of all marine vinyl runs at 90 degrees horizontal and vertical. When you stitch on it in the straight up and down / side to side position, it’s easier for the parallels to push apart from each other adding to your deformation. If you cant the vinyl at 45, you have the substate running at diagonals to the stitching and it’s harder to deform.
3) USE WSS topper. But it doesn’t need it, you say? Yes, yes it does. WSS helps the stitches stay “floated” on top of the vinyl rather than sinking down. When stitches sink down, they separate from each other allowing vinyl to peek through. WSS helps keep the stitches from sinking. No sinking, no peeking.
4) Blood sacrifice of a virgin goat under a blue moon while singing the Battle Hymn of the Republic – backwards.