By Robert Martin

(December 26, 2011) As polyester strings become more popular, the hybrid is also gaining a large following, primarily from people that want the advantage of polyester without the harsh feel. Of course this is not a perfect system, and an extensive procedure of trial and error is the usually the way that one arrives at the perfect string, or combination of strings.

In my case, I restring often enough that I do not need to look at a durable string, but I do use polyester in the crosses in order to firm up the feel of my flexible racquet. Tecnifibre was the first manufacturer to combine nylon and polyester into a single string, called Promix.

The idea was to use the typical multifilament construction that Tecnifibre is known for, and increase the durability by including a percentage of small polyester filaments. As the years have gone on, the percentage of polyester has increased in these strings, and Duramix HD was born with 50 percent polyester.

One of the largest issues with polyester strings in general is how quickly they lose their resiliency, and this was a concern before testing. I am used to either breaking strings or cutting them out after eight hours of play, which is too long for a string like Luxilon ALU Power 1.25.

With this in mind, I strung up a set of Tecnifibre Duramix HD 1.25mm in my Yonex RDiS200 320g at a usual tension of 28/26kg.

Groundstrokes:
Despite being 50 percent polyester, this string had a pretty muted feel from the baseline. It was firmer than the normal multifilament, but nowhere near the stiffness of traditional polyester.

I was pleasantly surprised that the string had a good amount of power without feeling mushy like some of Tecnifibre’s softer strings. On the forehand side, the string did not have the same level of spin and control as a full polyester, but for the added comfort, it was something I am willing to trade.

On the backhand side, which I tend to hit flatter, the string helped provide good control and depth. The sweet spot was pretty typical in size, maybe slightly smaller than my normal hybrid set up.

Volleys:
Made up of polyester and nylon, this string did not have the same touch as my normal hybrid that uses a multifilament string in the mains. That being said, the feel was not bad, it was simply different from what I am used to and the result was that a few attempts at drop volleys popped up on me.

Once I adjusted to the string I was able to get plenty of depth and pace on the volley and put points away quickly.

Serves:
While I feel that poly gives plenty of spin and control advantages on ground strokes, it seems to hinder my serve more than it helps. This is one of the reasons that I use the multifilament string in the mains of my usual hybrid so that I get that extra pace on the serve.

With Duramix HD, it was right in between the two. I was able to get some of the pace of a multi, but at the same time lost some of the spin like I would with polyester. This made serving the weakest attribute of the string for me, as I lost both pace and spin which takes away some of the free points that I rely on.

Final Thoughts:
Tecnifibre had a solid idea behind this string, but I do not feel that they delivered quite what they were hoping. The ideal string would be able to combine the spin and control of polyester, with the resiliency and comfort of a multifilament.

Duramix HD did not do that exactly, but made strides towards each side. For players that do not want to experiment with hundreds of thousands of hybrid combinations, this is a solid starting choice to try, but overall it lacks something in all departments.

Another way to interpret the result is that while the string does not have an amazing strength, it does not possess any glaring weakness either. The string began to fray after 3 hours of hitting and a noticeable tension drop occurred around the five-hour mark, but the string was still holding on when I cut it after eight hours.