Suddenly finding dark spots or discolorations on your pallets and crates can be concerning for many companies, but is it mold or just staining?
For some industries, such as food and beverage and pharmaceutical, finding mold means that the wood packaging sitting in their arsenal can’t be used if it has mold on it.
While mold has a minimal impact on the lifespan of the wood packaging itself, mold on pallets and crates can damage a manufacturer’s products, contaminate their product lines, and even pose some health risks.
The good news is that there are many things you can do to prevent or remediate mold on wood packaging. This guide will cover all of that and more.
Is It Really Mold?
Mold is a type of fungus that produces pigmented spores and can grow on the surface of wood packaging. Thousands of molds grow on wood, feeding on the structural polymers, sugars, and proteins in the wood.
Generally, molds produce spores that are black, white, green, orange, or purple spots on the wood.
Mold spores can easily spread to damp surfaces, including wood products. Depending on the mold species, surfaces available, and environmental conditions, spores can grow and spread in a few days but take months or even years to spread.
Conner Industries specializes in ISPM-15 certified export packaging, custom pallets, and crates designed for industries like food, beverage, and pharmaceuticals, where mold prevention and compliance are critical.
Staining
Before you start ordering new wood packaging replacements, you need to understand that sometimes what initially looks like mold is just natural staining of the wood. When you see discoloration on your packaging, you must ask yourself, “Is it really mold?”
Wood discoloration can look scary, but it’s non-biological and is not caused by microorganisms such as fungi or bacteria.
In contrast to mold, wood discolorations or staining can be caused by sun exposure, naturally occurring enzymes, minerals, fasteners, or even generated from the wood itself.
With over 40 years in industrial packaging, Conner Industries provides engineered wood, corrugate, foam, and integrated packaging solutions to help manufacturers safeguard their products.
Iron Stain
Iron stain is a prevalent type of black stain found on wood packaging.
It’s caused by a reaction between the elemental iron, usually in the form of the fasteners, and the natural enzymes in the wood. When the metal comes into contact with the wood, like nails, staples, and other types of fasteners, it discolors the wood over time.
Because iron stains interact with water, woods with lower moisture content are less affected by this staining. Iron stains are purely cosmetic and do not affect wood packaging.
Discoloration Caused By Enzymes
Hardwood species, such as oak, maple, and beech, are the most commonly susceptible to discolorations caused by natural enzymes.
Enzymatic discoloration occurs when the natural enzymes react, causing wood parts to take on a gray or brown tone. These are cosmetic changes that don’t affect wood packaging strength.
Mineral Discolorations
Wood discolorations resulting from minerals are often seen differently, depending on the wood species.
In oak, mineral discolorations present as dark lines or streaks; you may see green or brown patches in maple and purple or black areas in yellow poplar. Mineral discolorations sometimes occur when trees are standing in mineral-rich soil.
These types of discolorations don’t cause any damage to the wood or compromise its strength.
Blue Stain
Blue stain slightly differs from the other types of discoloration.
This type of stain is caused by microscopic fungi that sometimes infect the sapwood of trees.
This fungus produces a blue and gray discoloration of the wood, often in the form of spots, streaks, or patches. Note that blue stain does not cause decay, has no effect on wood strength, isn’t airborne, and is not linked to any health issue.
Sun Exposure
Wood exposed to the sun’s UV rays over an extended period will darken and even turn gray.
This weathering happens because the sun causes chemical changes to the tannins in the wood, similar to oxidation. Sun exposure can make your wood packaging look damaged and dirty, but the effects are only cosmetic. Sun exposure does not affect the strength of wood packaging.
How Can You Tell the Difference?
Sometimes, like an iron stain, you may look at staining rather than mold.
In the absence of a professional, there are some other clues you can look for to determine whether the discoloration you’re seeing is mold or staining.
- Moisture in the wood causes mold, so the presence of moisture may indicate a mold problem.
- If the wood structure looks damaged, in conjunction with discoloration, you may have mold.
- If the wood seems completely intact but slightly discolored, it might be staining.
- If you can see spores on the surface of your wood packaging, you’re probably looking at mold.
- You likely have sun exposure if your wood packaging is grayed out and sitting outside.
- If you see streaks or stains emanating from the nails or fasteners in your wood packaging, likely, you’re simply seeing iron stains.
What To Do Next
If you discover that your packaging is really affected by mold (or if you’d like guidance on preventing it altogether), partnering with a trusted packaging expert can make all the difference.
At Conner Industries, we design and deliver wood packaging that meets the strict requirements of industries where safety and quality come first.
Get in touch today to learn more about our custom pallets and crates, and connect with our team to find a packaging solution built to protect your products from start to finish.
