The origin and nature of “Pinking” as it occurs in marine seating

Informative excerpt from Boating Magazine on the origin and nature of “Pinking” as it occurs in marine seating. By Jim Hendricks 

You pull the cover off your boat one day and are met with unsightly, blotchy pink stains on your vinyl cushions and upholstery. WTH? You try every cleaning agent known to man, but nothing eradicates the stains.

These stains are not from a spilled drink or chemical or fluid. These permanent stains are the result of, “pinking,” a bacterial stain that is affecting boats all across North America.

The scourge is called pinking, and it is one of the least discussed topics in the boating industry. Companies stay tight-lipped about it because, until recently, there has been nothing that anyone could do to fix it short of replacing the upholstery.

Source of Pinking
“It’s a nasty problem and huge inconvenience for boat companies and upholstery suppliers,” says engineer Scott Laster, CEO of Gestalt Scientific Corp. in Redmond, Washington. “Pinking affects 10 to 20 percent of boats worldwide.” Based on 12 million boats in the United States, that means anywhere from 1.2 to 2.4 million boats suffer from pinking in this country alone.

“The stains are caused by a strain of bacterium known as Streptoverticillium reticulum that infests boat upholstery between the top layer of foam and underside of the vinyl,” Laster reveals. This strain occurs virtually everywhere and is normally harmless, he adds. But once it finds its way into vinyl upholstery, usually through the tiny holes in the stitching or other seams, problems begin.

Research shows the problem is more prevalent on boats that frequent freshwater rivers and lakes in the Southeast and Pacific Northwest. The company’s data also indicates that the bacteria cannot live in salt water.

“This bacterium needs four things to establish a colony in vinyl upholstery,” Laster explains. “It requires oxygen, fresh water, warmth and food.” The first three elements are easy to find in a lot of boats, especially ones in humid climates. Food, on the other hand, requires people — the bacteria feed on the oils and sloughed-off cells from human skin, as well as the chemical para-aminobenzoic acid (PABA) found in some sunscreens.

Pinking occurs when the bacteria run out of food and begin to die. “Through a metabolic process, the bacteria secrete a red dye,” Laster reveals. “The dye is then wicked up through vinyl material, and this results in blotchy pink or light red stains on the surface of the upholstery.”

Preventive Steps
“To help prevent pinking, you need to eliminate the elements necessary for the bacteria to get established,” says Laster. To cut the food supply, clean the upholstery thoroughly after each trip. If you’re not washing the boat, wipe down all the vinyl with a clean towel at the end of the day. Also, avoid the use of sunscreens containing PABA.

To stem the supply of water, towel off the boat’s interior and its upholstery to ensure everything is completely dry before you put on the boat cover. Also, the cover should be dry, at least to start with.

Types Of Pinking
There are actually two types of pinking that affect marine PVC vinyl, according to Gestalt Scientific Corp. The most common is bacterial pinking, which we have discussed. The other is chemical pinking.

Chemical pinking arises from a byproduct of certain glues in marine cushions, which change to a pink or red color and then wick to the surface of the material.

It is triggered when another material such as a boat cover is left in contact with the upholstery. The vinyl is then subjected to excessive heat, and the result is chemical pinking, which appears in more geometric patterns than the blotchy nature of bacterial pinking.

To help prevent chemical pinking, don’t let a boat cover rest on the upholstery while the boat is stored. If you cannot avoid this, put a towel between the vinyl and the cover material.

“Pinking” is definitely a four-letter word. It is costly to correct and usually results in some amount of time “off the water”. It’s an elusive bacterial that can occur in most any marine environment. It is not a result of material or manufacturing. Proper cleaning and dry storage remain the best defense.

*Images courtesy of Gestalt Scientific.