FabricWholesaleDirect review: Ottertex® solution dyed polyester waterproof canvas × silver

I ordered 10 yards of marine grade canvas to craft cushion covers for a freshwater boat. After installation and taking it out twice, several of the seats completely discolored. Not all of the seats, just a few. And the discoloration didn't happen in "spots", it was the complete piece of fabric that was exposed to the sun.

I reached out to the FWD to confirm that both sides of the fabric had the protective coating, which they confirmed. Now they've finally written back to give me 3 suggestions on why it happened and left it at that. I disagree with each suggestion, because again, it happened after two consecutive outings in fresh water, it only happened to a few of the seats, and the complete piece of fabric discolored, not spots.

Their "suggestions":
Trapped Moisture and Micro-climate Heat: When canvas covers fit tightly over vinyl or foam pontoon seating, moisture can become trapped underneath during humid conditions. Combined with direct sunlight, this creates a high-heat, high-humidity micro-climate between the seat and the cover, which accelerates surface chemical reactions and leads to severe fading or spotting.
Environmental & Chemical Exposure: Outdoor fabrics exposed to marine environments often absorb salt spray, waterborne minerals, acid rain, or chemical residues (such as sunscreens, insect repellents, or cleaning agents). When intense sunlight hits these residual deposits, it can cause severe chemical discoloration that mimics UV degradation.
Extreme UV & Radiant Heat Reflection: Aluminum rails and bright surfaces on pontoon boats act as reflectors, concentrating sunlight and heat onto specific areas of the seat covers at levels significantly higher than standard outdoor exposure testing conditions.

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