One of our customers called in complaining about black spots that appeared on an image printed on Sihl 3689 Photo paper. The print had been laminated with OraGuard 210 film and looked fine initially. A few days later; black spots.
When prints don’t come out like they should, the tendency is to blame the printer or the media. Quite often, the source of the problem is in our processes. The blemishes on the print were not caused by any defects in the printer, ink, or media. So what made a good print go bad?
Outgassing: It’s a good thing.
Outgassing was the culprit; more precisely, the customer’s failure to allow proper time for outgassing before laminating.
So what is “outgassing” and why is it necessary? In order to understand outgassing, we have to review how solvent and ecosolvent inks work. The solvents in these inks penetrate the surface of the media and carry the colorants into the fabric thereof. This penetration is what keeps your image from being left entirely on the surface where the sun’s evil UV rays can bleach it. This is why ecosolvent prints are rated for up to three years outdoors without lamination. Full solvents use stronger chemicals, penetrate more deeply, and are rated for up to five years without lamination.
But what happens after those solvents carry the resins down into the media? They evaporate. That evaporation is called–you guessed it–outgassing. And it generally takes about 24 hours to complete. If a solvent or ecosolvent print is laminated before this outgassing process is done, some of those solvents will be trapped beneath the overlaminate film and may react chemically with the film’s adhesive. The more quickly the print is laminated, the more solvents get trapped. Bad things happen. The consumer price index goes up, dogs run wild in the streets, and more importantly, black spots appear on your print!
Optically clear overlaminate film? Not anymore.
This is especially problematic when you’re laminating perforated window film. Because of the reduction in interior visibility, only optically clear overlaminates should be used for this application. This maximizes outward visibility for occupants of a wrapped vehicle. If you apply the overlaminate before outgassing is complete, the trapped solvents begin to chemically interact with the adhesive and cause silvering, a cloudy effect that ruins the optical clarity of the film.
To prevent these calamities, always, always, ALWAYS allow 24 hours for outgassing before applying overlaminate film to any solvent or ecosolvent print. It takes a little patience, but you’ll be glad you did.