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Solvent migration and retention causes catastrophic vinyl failure. Diffusion can cure the problem.
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By Rob Ivers
Rob Ivers owns Rob Ivers Inc. (Raymore, MO), a vehicle-graphics and installation company. He’s taught vinyl-graphics installation since 1993.
I don’t print graphics myself; I install them – mostly wraps. As a professional graphics installer, the biggest problem I face is solvent retention, which can lead to graphic failure regardless of how well I install the print. Most graphics sent to me haven’t been perfectly cured, but they contain varying degrees of solvent retention. I return severely undercured graphics to the sender.
Several telltale signs indicate when a print contains too many solvents. First, the smell can almost knock you over. Second, some shrinkage may have occurred. Finally, when in doubt, peel back a corner of the print from the liner and look closely. If it curls or feels soft and gummy, the print will likely cause problems.
If you own a solvent inkjet printer, this article is for you. It’s in no way intended to be critical; rather, my goal is to help you solve this problem.
Solvents 101
Ink solvents act as carriers that deliver ink to the vinyl surface. On contact, the solvents soften the vinyl and migrate towards the adhesive, a process known as solvent migration. Solvents are supposed to escape through diffusion, not remain in the same place. Diffusion is the process whereby liquid, solid or gas particles, spurred by kinetic energy, move from areas of higher concentration to those of lower concentration.
We also refer to the diffusion process as “curing.” If allowed to cure completely, all solvents diffuse and yield a quality printed graphic that’s ready for lamination and installation. Incomplete curing retains solvents within the adhesive and vinyl.
This problem is more common than you might think. In fact, it’s probably the norm. Solvent retention is extremely detrimental to both the vinyl and adhesive. Solvents constitute 80 to 90% of a solvent ink’s composition. Compound that by the number of inks used to create a digital print. Most devices use a minimum of four ink colors (CMYK), and many use six or even eight. So, a beautiful print is produced with a little ink and lots of solvent.
The proving ground
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