This is the most asked question we get and the answer is complicated to say the least. The average person would see little difference between polypropylene and polyethylene. To the naked eye, both fabrics look very similar and have similar properties such as high strength, long life and can use used in a variety of applications. Traditionally, polypropylene has been the more popular of the two in North America, based primarily on availability and price. Of the two fabrics available, polyethylene (HDPE) has more advantages than polypropylene (PP). Polyethylene is generally stronger, has better UV resistance, and is also more pliable which allows the manufacturer the choice of weaving or knitting. Most attempts to knit polypropylene have resulted in failure. Both fabrics can be uv stabilized and are resistant to most chemicals, mildew and fungus.
We sell our woven and knitted shade fabrics all over North America. We are not in a position though to advise a grower on what they should be using to protect their plants. Our expertise is supplying fabrics that will give the grower the best woven or knitted fabrics to cover their shade structure. What works in one area of the country may not do the same in another region. Our best advice to any potential grower is to discuss your needs with your local county extension agent or one of our distributors in your area.
This one is easy. Woven shade on a one to one basis is less expensive than knitted shade. The reason for this price difference is that knits require a lot more yarn to create the same shade percentage as its woven counterpart. On the other hand, in many applications, a knitted shade panel does not need an edge that is reinforced with tape and grommets. For commercial growers woven polypropylene is the fabric most professionals will go with. In certain parts of the country knitted shade is the fabric of choice based on appearance and superior strength.
Knitted polyethylene and woven polypropylene are fire resistant, but they are not fire retardant. Both fibers can be made fire retardant, but it is a very expensive procedure. The fire retardant additive and the color pigment are not compatible. When these two chemicals are combined during the extrusion process, they have an adverse affect on the extruder and will shorten the life of the fabric by at least 30%. Most weavers and knitters will not stock a fire retardant fabric based on the damage to the extruder, the high cost of raw material and the limited demand for this product.
Our background is supplying roll goods to fabrication operations. We do not want to compete with our distributors. We have worked hard to establish a trusting relationship with our distributors and we have no intentions of competing with them. If you need your fabric customized, we can refer you to a distributor who services your area.
Both fabrics have a plus and minus factor. Woven fabrics have the yarns placed one over and one under depending on the weave. You get a better coverage of yarns in a woven fabric, which results in a lower cost. On a one to one basis, woven fabrics cost less than a knit. The minus side of a woven fabric is the fact that in most applications, the edges of the fabric (selvages) will have to be reinforced with a binding tape and grommets. The basic construction of knits has the yarns interlocking providing a more stable fabric with superior strength. On the minus side it takes a lot more yarn to make a knitted fabric over a woven fabric. In many applications a knitted panel or tarp does not need fabrication. The panel or tarp can be attached in a variety of methods including plastic wire ties, s hooks, hog rings, nails or heavy duty staples. Both knits and wovens are U.V. stabilized to ensure the end user many years of service.