How to read and compare COTFIX fastness and solubility data
Use the published tables to compare an exact grade's reported values, then ask for the applicable method or lot evidence before relying on the number for a different process.
Published 6 October 2026 · Technical review and release approval completed by Shravan Goyal, Director.
What this data can and cannot tell you
Nuchem's COTFIX tables publish grade-specific values for solubility at 30°C, dry and wet rubbing, light, washing and dischargeability. They are catalogue statements for comparison, not lot-specific certificates of analysis. The current website does not name the test methods or conditions behind every column, so use the tables to shortlist a grade and request the applicable method or lot evidence before relying on a value for a different process.
1. Start with the exact grade row
The eight series tables contain 58 catalogue rows representing 57 distinct displayed trade names. Compare the row for the selected grade rather than applying one value to a whole series. A suffix such as a strength percentage is part of the displayed name and must not be treated as an interchangeable approval alias.
Example: D Series contains four rows. All four report solubility of 100 g/L at 30°C, but their published light and washing entries are not identical. H/P Printing contains twelve rows, with reported solubility values from 80 to 150 g/L.
2. Keep the temperature with the solubility value
The catalogue heading is Solubility gpl 30°C; gpl means grams per litre. Across the 58 rows, the displayed values run from 50 to 150. Cotfix Yellow HE4G reports 50, while Cotfix Orange P2R reports 150.
A larger displayed number is a different catalogue value, but the website does not currently state the solution preparation, endpoint, test tolerance or whether the number is a typical value or a minimum specification. Confirm those points before comparing the number with another supplier's data or using it to design a production recipe.
3. Keep dry and wet rubbing separate
Dry and wet rubbing are separate columns, so do not reduce them to one “rubbing fastness” claim. Cotfix Black WNN reports dry rubbing 4 and wet rubbing 4. Cotfix Yellow D reports dry rubbing 4–5 and wet rubbing 3–4.
The catalogue does not currently identify the rubbing method, instrument, wet condition or assessment scale. If a buyer specification names a standard and pass level, request the matching method and applicable result for the selected grade or lot.
4. Read light and both washing columns separately
Light is shown under Light Fastness 1/1 S/D. Washing is divided into Shade and Cotton. Treat them as three separate entries rather than one all-round rating.
The headings alone do not establish the light exposure method, the meaning of 1/1 S/D, the washing conditions or how Shade and Cotton were assessed. Those interpretations remain held until Nuchem confirms the applicable method definitions.
5. Check dischargeability independently
In the COTFIX tables, D means dischargeable, PD means partially dischargeable and ND means not dischargeable. These labels describe the listed shade's catalogue classification; the D label is different from the name of the COTFIX D Series.
Example: Yellow RR is marked PD, Red RR is marked ND and Blue RR is marked D. The label is not a discharge-printing recipe, production guarantee or proof of approval coverage.
A practical comparison checklist
| Question | Use the catalogue for | Confirm separately |
|---|---|---|
| Which grade? | Exact displayed name and series | Strength variant and approved alias |
| Solubility? | Reported value at 30°C | Method, endpoint and specification type |
| Fastness? | Separate dry, wet, light and washing entries | Standard, conditions, scale and lot result |
| Approval? | Route to product-specific records | Exact product, conditions, date and scheme scope |
What to send with a technical enquiry
Provide the exact COTFIX grade and strength variant, fibre, dyeing or printing process, target shade and depth, required test standard, whether dischargeability matters, expected volume and required approval documents. Ask for the applicable method or lot record if the decision depends on a particular performance value.