When rain pours or water splashes, you need a strong check to keep things safe and above water. One of the most useful tools for this check is tarpaulins – also called tarps. People use tarpaulins for camping, covering goods, and protecting buildings. But have you thought about how they stop water? The answer lies in the science of waterproofing.
What is a Tarpaulin?
A tarpaulin is a large sheet made from sturdy material. Most tarps consist of plastic, like polyethylene or PVC. Some tarps are made from canvas that has been coated with a waterproof coating. They are designed to be light enough to carry, yet strong enough to resist tearing.
The function of a tarp is primarily that of a barrier to rain, wind, and sunshine. For the tarp to perform this function properly, it needs to stop water from soaking in. This is where waterproofing comes in.
How Waterproofing Works
Waterproofing is making a material water-resistant. It involves not just stopping drops of water; it means stopping a continuous amount of water from penetrating through the material, even under pressure. Think of a tent in a rainstorm – when the rain is heavy, and water continues to press against the outside of that material. If the material you have is not completely waterproof, the water will penetrate through. Tarps are waterproof for two reasons:
- Material itself – plastic-based products have very tiny gaps between their molecules. Therefore, stopping water from penetrating through.
- Coatings and treatments- canvas tarps are often treated or coated in basic wax, oil, or specialty coated. This creates a thin film to repel water so that the water will ultimately not penetrate into the material, but slide off.
The Importance of Surface Tension
Have you noticed that water sometimes forms little beads of water on top of your tarp? This happens because of something called surface tension. The waterproof coating makes the Clear Tarpaulin smooth and non-absorbent as well. The water molecules stick together better than they stick to the tarp; therefore, instead of spreading out, they roll off the tarp.
Seams and Joints are Important Too
Even though the fabric is waterproof, the weakest areas are often along seams where pieces are stitched or welded together. Higher-quality tarps to reduce the chance of leaks use heat sealing instead of stitching. Heat sealing simply melts the edges of the plastic together so that water cannot go through tiny holes.
Breathable Tarp vs Non-Breathable Tarps
Some tarps are completely sealed, meaning they are airtight and waterproof; others are what is called “breathable,” meaning they allow air to get through but not rain. Breathable tarps help cover items such as wood or plants when you do not want moisture to get trapped inside.
Why does waterproofing last longer on some tarps
Waterproofing does not necessarily last forever; sunlight, heat, and dirt can begin breaking down coatings. Tarps that are made of PVC and polyethylene usually last longer because the waterproofing is it is part of the tarp in the material, whereas waterproofing on a canvas tarp will need to be re-coated in a few years.
To prolong your tarp:
- Keep it clean and dry when storing it.
- Try not to drag it on a rough surface.
- Keep it stored out of the sunlight when not in use.
Everyday Uses of Waterproof Tarps
Many people use waterproof tarps for so much more than teardrop trailers, pop-up tents, and Jeffrey has used them for many purposes. Campers use them for ground sheets or to cover sleeping tents, farmers use them to protect hay and equipment, and builders cover materials or unfinished work so that they do not accidentally get wet in the rain. You will even find that you use tarps at home to cover lawn furniture or a leaky roof. Read This
Final Thoughts
The science behind tarps is simple. By using materials with tightly woven or knit molecular structures, special coatings that make tarps slip-resistant, and sealing seams with heat or glue, tarps create a durable water barrier. During other uses, waterproofing is especially needed during summer camping and protecting the other goods you are carrying from a storm. Waterproof tarps are a great piece of mind when using them in these situations.
Waterproofing does involve keeping dry, but moreover, it means protecting what really matters from the forces of nature. I hope when you see water rolling off a tarpaulin in the future, you will not think of magic, only more physics hard at work.
