Pink Stains On Vinyl: A Problem

April 12, 2018
Pink Stains On Vinyl: A Problem
Updated February 25, 20 to include information regarding pink stains on linoleum floor (please see further down below).

With boating season approaching, it’s time to address a common problem: pink stains on vinyl boat seats. If you own a boat, you will definitely be familiar with this issue.

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pink stains on vinyl boat seats

Pink stains on vinyl boat seat (photo credit:

What Are These Pink Stains on Vinyl?

Often these pink stains on boat seats look like spilled juice and can be incredibly noticeable on white vinyl.

Most people naturally assume it is caused by pink mold on boat seats.

In actuality, these stains are caused by a dye that originates from bacteria. The dye is produced by the actinomycete bacterial genus, Streptomyces. This organism was previously known as "Streptoverticillium reticulum pink stain".

It is not the only species that causes the pink staining problem, but it is one of the best-known offenders.

These bacteria can be found on the vinyl surface, as well as in the actual foam under the vinyl. Like most bacteria, they thrive in moist, warm environments.

Essentially a boat is their dream home, with everything they need to grow.

Linoleum, vinyl flooring, pool liners, PVC vinyl roofing membranes and any other areas where light colored plastic and polymer materials come into contact with water, are also susceptible to the Streptoverticillium reticulum pink stain.

See further down below to find our more information about pink stains on vinyl and linoleum flooring.

How Do Pink Stains on Vinyl Boat Seats Occur?

The dye, also known as prodiginine pigments, can migrate quite a distance from the source. This is because the dye is water soluble.

Even though a stain originates from one tiny spot, the dye can continue to move outwards from the source if moisture is present. This allows the stain to expand in size.

Additionally, if these bacteria are growing in one material, for example, the foam cushioning inside a boat seat, the dye can easily migrate upward.

This would permanently stain the vinyl upholstery that is on top.

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Streptoverticillium reticulum

Example of how pink dye migrates from the pink staining bacteria, Streptoverticillium reticulum (photo by: Thomson Research Associates, Inc./Ultra-Fresh).

In a Petri-dish setting, the bacteria are normally white or light pink in colour when looking at the surface of the organism (please see photo above).

However, when looking at the underside of the Petri-dish, the intense pink color can be observed (please see photo below).

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Bacterial that causes pink staining on vinyl and foam

The bacterial organism often responsible for pink staining of plastics, vinyl and foam. It is commonly mistaken for pink mold (photo credit: Thomson Research Associates, Inc./Ultra-Fresh).

In the "real world", the color of the dye can range from red to purple or pink to brown depending on growing conditions (food source, temperature, humidity levels, etc.).

What About Pink Stains on Linoleum Floor?

You may have found our blog because you were concerned about the pink stains on your linoleum or vinyl floor. Why is your vinyl floor turning pink?

These same bacteria are most likely the cause of the problem, especially if moisture is being trapped under your floors.

Bacteria could be growing on your subfloor with the dye migrating upwards over time, causing the mysterious pink stains on your linoleum floor to magically appear.

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Pink stains on floor caused by bacteria

Linoleum floor stained pink by dye-producing bacteria (photo credit:

Pink stains aren't the only types of stain that can occur on vinyl.

Orange to rust colored spots may appear and are attributed to mold and mildew that can also produce stain causing pigments, as seen in the photo below.

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Linoleum flooring stained by bacteria

Rust spots found on linoleum flooring caused by a mold producing orange or rust/metallic colored pigments (photo credit:

The following photo was taken in our laboratory and shows a brightly colored fungus that was isolated from stained vinyl.

This fungus likely responsible for the rust colored spots occasionally found on linoleum or vinyl flooring. Note the rust/orange/yellowish pigment that diffuses outward from the organism.

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Mold isolated from vinyl

Mold isolated from stained vinyl (photo by: Thomson Research Associates, Inc./Ultra-Fresh).

How to Remove Pink Stains from Vinyl

Ensuring your boat stays dry is one way to slow the rate of bacterial growth (or mold). Be sure to clean and store your boat properly, while keeping moisture levels to a minimum.

Removing pink stains from vinyl is not easy.

If you already have pink stains forming, there are some cleaners that can help lessen the appearance such as Gestalt Scientific's Pink Away, recently written about in Boating's online magazine.

However, there isn't anything available that will remove it completely.

Certainly, be careful if using bleach to try and clean these stains. It can cause unnecessary damage to the vinyl and stitching.

Be sure you are getting the best protection before the pink stain problem develops. Check with your upholstery provider to see if they are using Ultra-Fresh in their products.

How Ultra-Fresh Helps Combat Pink Stains on Vinyl and In Foam

Ultra-Fresh is an antimicrobial agent that helps prevent the growth of the Streptoverticillium reticulum pink stain bacteria. It can also inhibit a wide range of other types of odour and stain causing microbes.

The antimicrobial additive is incorporated during the manufacturing process and can be added to all components of marine seating (including vinyl, foam, and stitching thread).

It also has the added benefit of controlling unpleasant odors and prolonging degradation of the polyurethane foam and vinyl (the organisms that cause pink stains on vinyl have a characteristic earthy type odor).

The Ultra-Fresh technology is highly effective. It is EPA registered, BPR listed and does not contain any of the chemicals listed on California's Proposition 65 warning list as of February 25, 2020.

Test Method Used to Assess Pink Stains on Vinyl

A common test method used to assess materials against pink staining, using the Streptoverticillium reticulum pink staining test organism, is the ASTM E1428.

The pink staining bacteria are swabbed across the surface of an agar plate containing nutrients for the organism to grow.

The test sample is placed on top of the swabbed surface and incubated for 14 days. Afterwards, the sample is peeled from the surface and assessed for the degree of pink staining.

Below is an example of a vinyl treated with an antimicrobial additive, along with an untreated vinyl sample:

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antimicrobial treated vinyl

Ultra-Fresh antimicrobial treated vinyl inhibits bacterial growth, preventing development of pink stains.

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untreated vinyl

Untreated vinyl stained pink by Streptoverticillium reticulum that produces dye as a waste by-product.


Unfortunately, removing pink stains from vinyl is very difficult to accomplish after the fact. If your product is within warranty, speak with the manufacturer to see if there is anything that can be done to replace the item.

If you have the chance to start again from scratch, the following points are important to remember to prevent the pink discoloration from happening again.
  • Ensure the product is treated with an antimicrobial technology that is proven to pass the ASTM E1428 test method
  • Keep your product clean and protected from dirt
  • Limit moisture: For your boat, ensure the upholstery has an opportunity to dry completely. Don't leave wet towels or bathing suits on the seats. For linoleum or vinyl floors, take care of any existing moisture issues that may be occurring underneath the flooring.
To learn more about Ultra-Fresh and how it helps combat pink stains on vinyl or in polyurethane foam, contact us today!

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Our Antimicrobial Expertise

Thomson Research Associates (TRA) is a global leader in the field of antimicrobial treatments, providing technologies that impart bacterial and fungal efficacy to finished products for over 60 years.

We are committed to helping our clients deliver fresh, durable and innovative products by providing antimicrobial additives and treatments for fabrics, polymers, foams, coatings and more.

Our ultimate goal is to satisfy our clients’ specific needs through excellence in service, science, and support. Find out how we work with you through our scientific testing laboratory, highly-qualified technical and regulatory specialists.

We offer a selection of products, including options that are US EPA registered, BPR compliant and OEKO-TEX® listed.

Furthermore, acknowledging our social responsibility, we have partnered with bluesign® in our joint initiative for the removal of harmful substances and practices from the manufacturing process.

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