Poly tarps have become quite ubiquitous since they were first brought to market in the 1930s. But canvas tarps existed for hundreds of years before the invention of plastic, and many people still prefer them. There are a variety of reasons to choose canvas, just as there are reasons to choose poly or vinyl.
Ultimately, which tarp material you should buy largely depends on where and how it will be used. Canvas tarps have beneficial features, but they also have drawbacks.
What is a Canvas Tarp?
Canvas tarps are manufactured from cotton cloth that is treated with oil- or wax-based materials. Specifically, the cloth is cotton duck, which is a heavier, more tightly woven material than standard cotton cloth. A standard canvas tarp has a number of grommets or D-rings in its corners and around the sides to facilitate securing it in place.
Key Features of Canvas Tarps
Breathability A dry canvas tarp allows air to pass through. This can absolutely be beneficial in some circumstances. For example, the humidity of a heavy rain can leave moisture beneath a tarp that may result in condensation. With a canvas tarp, that humid air can pass back through the tarp on a sunny day. The only tarp more breathable than canvas is a mesh tarp, which isn't remotely waterproof.
Slip-Resistant In situations where people will need to walk on your tarp, canvas provides significantly more traction than polyethylene or vinyl.
Water-Resistant Whether oil-based or wax-based, the treatment on a canvas tarp causes rain to bead up on the surface and roll right off.
Environmentally Friendly Cotton is a renewable resource, and--given enough time--a discarded canvas tarp will eventually decompose.
Optional Features for Canvas Tarps
Untreated While uncommon, it is possible to manufacture a "natural" canvas tarp, meaning that it has not been treated to be water-resistant.
Flame Retardant There are a number of applications that require tarps to be resistant to fire. This requires an additional treatment.
Disadvantages of Canvas Tarps
Not Waterproof It's important to note that treated canvas tarps are only water-resistant. While rain does bead up and roll off the surface, standing water will slowly seep through the material. Canvas tarps cannot be fully waterproof like poly tarps.
Not Tear-Resistant You should prevent any tarp from being punctured, but canvas tarps are especially vulnerable to additional damage if pierced. Once a hole is formed, the cotton weave can tear easily. The best way to prevent tears in a canvas tarps is to prevent puncture damage.
Shrinkage Canvas tarps can shrink and stretch with changes in humidity and temperature.
Final Thoughts
Canvas tarps are versatile, environmentally friendly, durable, and breathable. Many people like canvas tarps for the vintage aesthetic and feelings of nostalgia. There are many applications where a canvas tarp is quite effective. Before you purchase one, consider whether its disadvantages make it the wrong choice for your situation. As long as these are considered, and you take care to handle your tarp properly, a high quality canvas tarp can be an excellent investment.