What is Mottling Vinyl? Why is my vinyl blotchy?
I have seen a lot of vinyl in my day and mottling vinyl is thankfully not common. Most rolls we receive are perfect with no flaws. On occasion we do get rolls of pressure sensitive vinyl (from all manufacturers we carry) that has a cloudy or blotchy appearance scattered throughout the roll. The common industry term for this is mottling.
The higher the gloss finish of the vinyl, the more likely it will have mottling. Mottling is a result of the plasticizers in the film migrating to the film surface, creating a cloudy, hazy or blotchy appearance on top of the film. The addition of plasticizers results in a surface that is soft. When vinyl is rolled on a core, the backside of the liner is in direct contact with the surface of the vinyl. The contact of the vinyl surface to the liner interferes with the smooth surface that gives the film a high gloss appearance. This embossing contact can result in a lower gloss appearance. Usually this disruption is not uniform due to possible variations in thickness of a vinyl resulting in the blotchy appearance.
In my experience the tighter a roll is on a core and the closer to the end of the roll, the more the mottling will be visible. But not in every roll. Mottling seems to be more common during temperature variations. Such as going from cool to warm or warm to cool. Think about how long vinyl travels on a freight truck with extreme temperatures before it arrives to us. We then bring it into our temperature-controlled warehouse and then send to you on a shipping carrier truck for a few days. This swing in temperatures and humidity can cause the liner to swell and create great contact with the vinyl film resulting in the blotchy appearance.
Luckily Mottling is not a defect in the vinyl. It is simply a temporary flaw.
Warmth is the best way to eliminate mottling. When you receive your vinyl I recommend removing from the plastic so it can “breathe” and if it is a large roll it wouldn’t be a bad idea to loosen up the vinyl around the core. The goal is to get the vinyl up to room temperature (ideally 70-75º F). I have also seen customers just roll with it and cut decals while the vinyl is still blotchy. Once the decal has sun exposure the vinyl will go back to glossy.
Understanding mottling allows our customers to take the proper measure to deliver a great product to the end user. If you have further questions, please reach out to us by email or phone.