PTFE 4:1 Fractional Heat Shrink

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Zeus fluoropolymer heat shrink provides a perfect method for the application of a tight, protective jacketing to items subjected to extremes of heat, corrosion, shock, moisture, and other severe exposures. Heat shrink protection extends the life of the covered components and helps sustain their performance. PTFE’s low coefficient of friction, biocompatibility, and chemical resistance have made it the polymer of choice for many of these applications.

We are the largest extruder of polytetrafluoroethylene, or PTFE. This highly popular material has become the gold standard for fluoropolymer tubing because of its superior lubricity, temperature endurance, and chemical resistance. As tubing or heat shrink, this polymer is highly embedded in applications ranging from medical devices, industrial, chemical, and analytical areas. Zeus PTFE heat shrink provides secure encapsulation to protect your vital components.

PTFE’s broad temperature tolerance -328 °F (-200 °C) to 500 °F (260 °C) makes it one of the few plastics that can be utilized in high and low temperature applications. PTFE possesses excellent dielectric strength making this heat shrink well-suited for encapsulation of wires and electrical devices. For outdoor use, PTFE heat shrink is virtually impervious to weather. With a 4:1 shrink ratio, this heat shrink is able to cover highly irregularly shaped parts.

Zeus heat shrink tubing products are provided in their expanded state. With a brief application of heat, these materials mold themselves snugly around intricate and irregular shapes forming a completely sealed covering. Sources of heat and methods of heating can vary. Please contact a Zeus Technical Account Manager to assist you in selecting the heat option best suited for your application.

Contact our team or call toll-free in the US 1-800-526-3842 or +1-803-268-9500 internationally today to see how we can develop a precision solution to give you a competitive advantage or to request prototyping samples.

Shrink Ratios and Recovery

Heat shrink ratio refers to the final diameter of the heat shrinkable material after being allowed to shrink fully unrestrained compared to the original diameter of the pre-shrunk material. After heat shrinking is complete, the material is considered to be in its “recovered” or “recovery” state. Thus, final dimensions for heat shrink usually refer to recovered or fully shrunk dimensions.

As an example, for a heat shrinkable material with a 4:1 heat shrink ratio, the final diameter of the fully shrunk (recovered) material will be reduced to 1/4 of the pre-shrunk diameter. Or, put another way, the original diameter of the pre-shrunk material will be 4× the diameter of the fully shrunk (recovered) material; the ratio of their diameters, pre-shrunk:recovered, will be 4:1.

Note that heat shrink is applied over a material or component to encapsulate it. Thus, in practical application, the heat shrink is restrained from being able to shrink fully.

Heat shrink ratio is a fundamental consideration for every application based on the degree of non-uniformity of the items or components to be covered. The more irregular the shape, the greater the heat shrink ratio needed to cover the shape. For more uniform parts such as cylinders or wires, smaller heat shrink ratios are usually sufficient to achieve proper coverage. Consideration should also be given to tapered parts: While appearing generally uniform in shape, the degree of taper should be taken into account when selecting heat shrink and its shrink ratio.

Heat Shrinking Guidelines for PTFE Heat Shrink Tubing

  1. Always assure good ventilation in the immediate work area before beginning the heat shrink process. (Caution: Fumes can cause nausea and dizziness).
  2. PTFE heat shrink tubing requires approximately 650 °F ± 25 °F (340 °C ± 5 °C) to initiate shrinkage. While this is a liberally safe range, these temperatures are approximate. Actual shrink temperatures may vary based on dimensions and wall thickness of the tubing, methods heat of application, and other factors. Zeus is happy to provide samples to test in your application and help you determine the best material to use.
  3. The part to be covered by the heat shrink must be able to tolerate the range of the heat shrink temperature.
  4. Parts or mandrels may act as a heat sink which may cool the heat shrink prematurely or require more time to reach the necessary temperature. Therefore, Zeus recommends preheating larger diameter mandrels and other parts.
  5. Generally, heat shrink should be allowed to recover a minimum of 20%. You may experience some slight longitudinal change depending on the amount of recovery. Contact Zeus if longitudinal change is a concern.
  6. Heating and cooling should be even on all sides for best results. Uneven heating or cooling tends to split the side of the heat shrink that is still in the “gel” state while the other side may be in the hard or crystalline state, particularly upon recovery.
  7. Ovens are the most reliable way to recover heat shrink products: Their generally more even heating reduces the risk of overheating the material (which can lead to brittleness and cracking). If a heat gun is to be used, please contact Zeus for tips on proper heat application to achieve the most uniform recovery.

Zeus PTFE heat shrink tubing is available with of 4:1 and 2:1 shrink ratios and can be selected based on American Wire Gauge (AWG) or fractional sizes. This heat shrinkable material incorporates all of the same high standards and qualities for which PTFE is known. We also provide custom specifications and tolerances including our Sub-Lite-Wall® sizes upon request.

Applicable Specifications

PTFE Heat Shrink complies with AMS 23053/12.

For all cases of military or commercial specifications, the latest revisions apply. This heat shrink is supplied in natural (translucent) color unless otherwise specified.  Mil-STD-104 colors are available upon request.

PLEASE NOTE: Some of the items above meet UL-224 certification. See our UL chart for the latest information.


    Encapsulation – PTFE heat shrink provides protection from a range of environmental extremes for your critical components. This heat shrink can easily tolerate wide temperature ranges, exposure to chemicals, and long-term weather exposure. PTFE heat shrink can be used to cover such items as temperature probes, metal roll covers, wires and cables, electronics, sensors, to name but a few.

    Insulation – PTFE heat shrink’s dielectric properties make is a good choice for encapsulating and insulating electrical components including batteries (lithium and alkaline) and other electrical devices. PTFE heat shrink’s heat tolerance allows it to continue to perform at temperatures from the very cold to the very hot.

    Wire Harness – PTFE heat shrink’s excellent dielectric properties make is a good choice for covering wires and cables and can even support splicing. Once covered, PTFE heat shrink also serves as insulation, and its properties are retained across its wide working temperature.


    Biocompatible – Zeus PTFE heat shrink is non-toxic and USP Class VI approved, so you can trust its biocompatibility.

    Broad Working Temperature – PTFE has an extended service temperature range of -328 °F (-200 °C) to 500 °F (260 °C) allowing this heat shrink to be used in cryogenic settings such as for temperature probes to very hot environments.

    Chemically Resistant – PTFE provides reliable protection from almost all common solvents, whether acids, bases, or hydrocarbons.

    Easy To Clean – Because of the highly lubricious nature of PTFE, this material possesses a highly non-stick surface making it easy to wipe clean.

    Excellent Dielectric Strength – PTFE heat shrink has exceptional dielectric strength and thus doubles as insulation when used with electrical components.

    Flame Resistant – The non-flammable nature of PTFE makes it a good choice for environments where there is high heat or the possibility of flame exposure. PTFE is UL 94 V-0 rated.

    Limiting Oxygen Index – PTFE heat shrink is highly disinclined to burn; this fluoropolymer tubing has a limiting oxygen index of >95.

    Low Coefficient of Friction – PTFE has the lowest coefficient of friction of any polymer making parts, cables, or wires covered with PTFE heat shrink easy to maneuver into confined spaces to be placed at their point of use.

    Low Extractables – The very low level of extractables for PTFE means that contaminants will not leach out of the heat shrink and into the parts it is covering.

    Mechanical Resistance – Once covered with our PTFE heat shrink, the covered items have an increased mechanical resistance even under severe conditions; this is particularly beneficial for joined parts such as wire splices and other delicate connections.

    Sterilizable – PTFE heat shrink’s temperature tolerance and physical properties allow it to easily withstand ETO and autoclave sterilization protocols.



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  • Approximate Ratio of Expanded I.D. to Recovered I.D. (fractional inch sizes)

    PTFE 4:1 Fractional


    Ordered as Fractional Size Expanded ID Min. Recovered ID Max Recovered Wall Thickness Nominal Tolerance
      in mm in mm in mm in mm
    5/64 0.078 1.98 0.025 0.64 0.009 0.23 ± 0.002 ± 0.05
    1/8 0.125 3.18 0.037 0.94 0.012 0.31 ± 0.002 ± 0.05
    3/16 0.187 4.75 0.050 1.27 0.012 0.31 ± 0.002 ± 0.05
    1/4 0.250 6.35 0.063 1.60 0.012 0.31 ± 0.002 ± 0.05
    5/16 0.312 7.92 0.078 1.98 0.012 0.31 ± 0.002 ± 0.05
    3/8 0.375 9.53 0.096 2.44 0.012 0.31 ± 0.002 ± 0.05
    7/16 0.438 11.13 0.112 2.84 0.012 0.31 ± 0.002 ± 0.05
    1/2 0.500 12.70 0.144 3.66 0.015 0.38 ± 0.004 ± 0.10
    9/16 0.562 14.27 0.155 3.94 0.015 0.38 ± 0.004 ± 0.10
    5/8 0.625 15.88 0.178 4.52 0.015 0.38 ± 0.004 ± 0.10
    11/16 0.687 17.45 0.198 5.03 0.015 0.38 ± 0.004 ± 0.10
    3/4 0.750 19.05 0.224 5.69 0.015 0.38 ± 0.004 ± 0.10
    7/8 0.875 22.23 0.244 6.20 0.015 0.38 ± 0.004 ± 0.10
    1 1.000 25.40 0.278 7.06 0.015 0.38 ± 0.004 ± 0.10
    1-1/4 1.250 31.75 0.347 8.81 0.015 0.38 ± 0.004 ± 0.10
    1-1/2 1.500 38.10 0.400 10.16 0.015 0.38 ± 0.004 ± 0.10
    1-3/4 1.750 44.45 0.450 11.43 0.015 0.38 ± 0.004 ± 0.10
    2 2.000 50.80 0.520 13.21 0.020 0.51 ± 0.005 ± 0.13
    2-1/4 2.250 57.15 0.585 14.86 0.020 0.51 ± 0.005 ± 0.13
    2-1/2 2.500 63.50 0.650 16.51 0.020 0.51 ± 0.005 ± 0.13
    2-3/4 2.750 69.85 0.710 18.03 0.020 0.51 ± 0.005 ± 0.13
    3 3.000 76.20 0.775 19.68 0.020 0.51 ± 0.005 ± 0.13
    3-1/4 3.250 82.50 0.835 21.21 0.020 0.51 ± 0.005 ± 0.13
    3-1/2 3.500 88.90 0.900 22.86 0.025 0.64 ± 0.005 ± 0.13
    3-3/4 3.750 92.95 0.960 24.38 0.025 0.64 ± 0.005 ± 0.13
    4 4.000 101.60 1.025 26.03 0.025 0.64 ± 0.005 ± 0.13