For FEP insulation, start with an FEP-carrier colour masterbatch and confirm the loading on the actual extrusion line. Colour selection, let-down ratio and a finished-part trial belong together.
1. Start with the actual base resin
Identify the resin grade and whether the product is solid insulation, a jacket, tubing or another extruded part. Choose a masterbatch intended for that base resin and application. A matching colour name does not make PFA, ETFE or PVDF carriers interchangeable with FEP.
Durafluor supplies a dedicated FEP series with 11 standard colours referenced to RAL, plus custom matching to a customer's reference sample. The colour card is a starting point for selection; approve the colour on the intended finished part.
2. Use wall thickness to discuss the starting addition rate
Durafluor's reference ranges for wire insulation are:
| Insulation wall thickness | Reference masterbatch addition rate |
|---|---|
| 0.15 mm | 2–5% |
| 0.25 mm | 1.5–4% |
| 0.5 mm and above | 1–3% |
These are starting guidelines, not a universal recipe. Base-resin colour, opacity requirements, shade and finished geometry affect the final loading. Do not interpolate a guaranteed loading from this table. Confirm the recommendation for your application and validate it by extrusion trial.
3. Prepare a controlled production trial
Record the actual base resin, concentrate grade and batch, intended addition rate, finished dimensions and line conditions. Establish a consistent dosing and mixing method under your site's approved procedure so the agreed loading is reproducible.
Use the resin supplier's processing and safety instructions and the equipment manufacturer's operating requirements. Temperature profile, residence time, drying requirements and changeover procedures are grade- and line-specific; this guide does not prescribe one setting for every FEP line.
Evaluate the trial's colour, dispersion and surface appearance on finished parts, then test the properties required by the customer's specification. Keep a reference sample and record the approved conditions before scaling up.
4. Check the evidence for the exact material
All 11 standard Durafluor FEP colour grades have CTI test reports for RoHS restricted substances and halogen content. Request the report for the selected grade rather than treating a general statement as the product's test record.
SDS documents are on file for 33 grades across the FEP, PFA and ETFE series. PVDF SDS coverage is still being completed. Ask for the relevant TDS and SDS during qualification. A masterbatch report does not certify the finished cable or remove the need for application-specific testing.
5. Send a useful sample enquiry
Include the base-resin grade, application, wall thickness or finished geometry, target colour or reference sample, opacity requirement and applicable customer specifications. If available, describe the current colour or dispersion problem and the proposed trial conditions.
Durafluor can discuss the matching FEP grade, a recommended starting loading and the documents available for evaluation. Contact us through www.durafluor.com/contact/.
Quick answers
Can I use the same masterbatch when switching from FEP to another fluoropolymer? Do not assume interchangeability. Select the appropriate carrier series for the new base resin and re-qualify the finished colour and relevant properties.
Does a higher addition rate always fix weak colour? Do not adjust loading in isolation. Review the base resin, wall thickness, opacity target, dosing and dispersion, then agree a trial plan.
Is there one extrusion temperature for every FEP colour masterbatch? No universal setting is provided here. Follow the instructions for the actual base resin and equipment, and confirm the concentrate's suitability for the proposed processing window.