Guidelines for sizing up tarp quality and durability
If you’ve been shopping for tarps recently and come away confused after sizing up shelves full of different color covers identified as “good,” “better,” or “best” but not sure which one you need, you are not alone.
Some tarp manufacturers, particularly those that produce economically priced tarps, use terms such as light-duty, heavy-duty, or extreme duty to sell their goods rather than list the construction characteristics of the product.
Beyond the fact that tarps come in different colors with some tarps being heavier and more expensive (sometimes much, much more expensive) than other coverings, is there really much quality difference among similar size tarps?
Yes – and those difference are huge. Tarp quality varies not only by fabric but also by construction.
Color, by the way, has little influence on tarp quality except that lighter colors such as white and silver will reflect sunlight. Some buyers pay extra money to purchase a silver tarp assuming it is a better quality product when, in fact, color is no guarantee of quality.
What determines tarp quality? That would be the tarp’s material, thickness, mesh count, denier weight, lamination process, and stitching reinforcement.
The following information is garnered from numerous entities including the National Cotton Council (cotton.org), Creative Shelters (creativeshelters.com), Gemplers (gemplers.com), Tarp Nation (tarpnation.net), and Shur-Co Corp. (shurco.com).
Generally, the materials used to fabricate tarps include the following types.
- Polyethylene. These coverings are made from woven polyethylene terephthalate (PET) mesh or scrims (an industry term describing a coarse fabric made with a rectangular weave). They are coated with a polyethylene or (in the case of extreme or super heavy-duty tarps) polyvinyl chloride (PVC) film laminate. Poly tarps’ quality ranges from lightweight to heavy duty.
- Vinyl. Created from PET and PVC scrims, these tarps are double-coated with a PVC film laminate. Commonly used on grain trailer covers, vinyl tarps are heavier, more expensive, and heavy-duty in their service. Pricewise, they can be two to 10 times the expense of a comparative size poly tarp.
- Canvas. This was the tarp your grandfather or great-grandfather commonly used. Fabricated from highly durable plain-woven fabric (cotton or hemp), these tarps have largely been replaced by vinyl tarps as trailer coverings. Yet, these extra-heavy duty and highly durable covers still have a place on the farm.
The actual thickness of tarps is measured in mils (1 mil is 1/1,000 of an inch). The larger the number, the thicker the tarp. Lightweight tarps (often blue in color) are 5 to 6 mils. Heavy-duty tarps, on the other hand, can be 20 mils and thicker.
A tarp’s weight, listed as ounces per square yard, does testify to its quality. Vinyl tarps, for example, are two to three times the weight of a light or medium-weight poly tarp.
However, weight itself is not a complete indicator of quality, but it does indicate that a tarp has a more dense weave count and thicker thread used to make the scrim.
A tarp’s scrim or mesh has a weave count (also referred to as the yarn or thread count), which is listed as the number of threads (either PET or PVC) per square inch lying vertically and horizontally.
For example, a 12×12 weave count has 12 threads per square inch in both directions. The higher the weave count the heavier the tarp and also the more resistant it is to tearing.
This is a measure of the thread weight (grams per 9,000 feet of thread) used to make a tarp’s scrim. The larger the denier the more a tarp is resistant to tearing and wearing through. The denier is also known as the tarp’s linear mass.
Most tarps receive a coating that helps them resist UV (ultraviolet light) degradation. These treatments include hindered amine light stabilizers (HALS), butylated hydroxytoluene (BHT), and carbon black. The poly and vinyl coating on tarps is naturally waterproof, plus mildew- and rot-resistant.
The vast majority of tarps do not include a flame retardant. If you need flame resistance, then ask for a tarp that has been treated with a flame retardant.
Finally, sun-blocking tarps are made with an additional layer of black polyethylene to form a light-blocking material.
Seams and Hems
Seams on laminated tarps should be stitched and heat-sealed to inhibit water leakage. Good hems ensure tarp stability. The preferred hem is a wide seam containing at least two rows of lock-stitched thread with five to six stitches per inch.
Higher-quality tarps will have additional reinforcement around their perimeter to help prevent tearing. Reinforcement can include a perimeter rope (sewn inside the hem) and grommet reinforcement (reinforcement at each grommet, sometimes called a patch).