Some tube shaped polymer media are coated with an oleophilic material to improve oil adhesion, which may diminish over time as the coating is scraped off by the wiper blades or debris. In mop configurations, polymer fibers may get matted down fairly quickly by higher viscosity oils, reducing removal capacity. Some polymer media are laminated to improve resistance to stretching. Lamination also adds dimensional stability to resist bending, rolling and twisting caused by turbulence or debris in the water. To avoid problems with delamination, which is accelerated at higher temperatures, some manufacturers use a single layer of a specially engineered polymer that has higher strength and heat stability.
Stainless steel is reliable in high temperatures, acidic and alkaline solutions and in solvents.
It also is a good choice when the skimmer will be shut down for substantial periods, as it resists corrosion due to prolonged air exposure. In outdoor applications, the use of heaters may be required to keep skimmed product fluid so it can be effectively removed from the medium and collection tray. This is particularly true for grease skimming, which involves higher viscosities at all temperatures. Polymer materials are limited in their heat tolerance, so skimmers equipped with these media may have only tray heaters. Skimmers with steel media can apply heat to both the tray and the medium, which improves performance in severe winter climates.