Thermofixation for Direct Disperse Inkjet Printing: How Temperature and Time Interact with Pretreatment Chemistry

Thermofixation is the stage where direct disperse inkjet printing changes from a surface-deposited image into a dyed polyester structure. Temperature increases molecular mobility in polyester and accelerates disperse-dye diffusion, while time determines how long that diffusion can continue. But temperature and time do not act on the dye alone. They also act on the pretreatment polymer, residual auxiliaries, fabric structure and any surface film that was created before printing. A pretreatment that gives excellent pre-fixation sharpness can still reduce final color yield if it holds too much dye at the surface, while an aggressive thermofixation condition can increase diffusion yet also change migration, shade, surface residue or fabric dimensions. The correct process therefore matches disperse-dye class, polyester construction and pretreatment chemistry inside a validated temperature–time window rather than using one universal thermofixation recipe.

How Do Temperature and Time Interact with Pretreatment Chemistry?

Thermofixation should be viewed as a coupled dye–polyester–pretreatment process.

A useful process chain is:

Pretreatment → Pretreatment Drying → Direct Inkjet Printing → Post-Print Stabilization / Drying Where Required → Thermofixation → Reduction Clearing / Washing → Final Print

During thermofixation:

• Heat increases the mobility of polyester molecular segments in accessible amorphous regions.
• Disperse dye molecules gain mobility and diffuse from the printed surface into the polyester.
• Pretreatment polymers and auxiliaries remain around or on the textile surface and can influence how easily dye leaves that surface environment.

Therefore:

Temperature × Time × Dye Class × Pretreatment Chemistry × Polyester Structure

must be considered together.

There is no universal temperature and time that is correct for every direct disperse ink, polyester fabric and pretreatment.

Where Thermofixation Sits in Direct Disperse Inkjet Printing

Direct-to-fabric disperse inkjet printing normally separates image formation from final dye fixation.

The printer deposits an aqueous disperse ink accurately onto the polyester surface.

Before fixation, much of the dye is still concentrated in or near:

• The dried ink deposit
• The pretreatment layer
• The fiber surface

Thermofixation supplies the thermal energy needed to move the disperse dye into the polyester phase.

This is why a pattern can look sharp immediately after printing but still have:

• Low final K/S
• High surface dye
• Poor rubbing fastness

after washing if fixation is insufficient.

Direct Disperse Thermofixation Is Not Sublimation Transfer

This article focuses on direct disperse inkjet printing on polyester fabric.

In sublimation transfer:

• Ink is first printed on paper.
• Heat transfers dye from paper into polyester.

In direct disperse inkjet printing:

• Ink is deposited directly on polyester.
• The fabric may already contain a pretreatment polymer and auxiliaries.
• Thermofixation must move dye from that printed textile surface into PET.

The pretreatment–fixation interaction is therefore much more direct in the fabric-printing route.

What Happens to Disperse Dye During Thermofixation?

Disperse dyes have low water solubility and affinity for hydrophobic polyester.

At elevated temperature, molecular mobility in the less-ordered regions of PET increases, making dye diffusion into the polymer more favorable.

The simplified mechanism is:

Surface Dye → Molecular Mobility / Desorption → Diffusion into Accessible PET Regions → Retention inside Polyester

This is a kinetic process.

The final result depends on:

• Dye molecular structure
• Température
• Time
• Polyester morphology
• Pretreatment surface environment

1. Temperature Controls the Rate of Dye Diffusion

As fixation temperature rises within a suitable range, disperse-dye diffusion into polyester generally accelerates.

This can increase:

• Intensité de la couleur
• Dye penetration
• Removal resistance during after-treatment

Published direct-polyester inkjet work illustrates this strongly: one pretreatment system showed much higher K/S at higher fixation temperatures than at a substantially lower temperature.

But this does not mean:

Higher Temperature Is Always Better.

The optimum depends on dye class, fabric and pretreatment chemistry.

2. Time Controls How Long Diffusion Continues

At a given temperature, longer time generally provides more opportunity for dye diffusion.

If time is too short:

• More dye can remain near the fiber surface.
• Post-wash K/S can remain below its achievable level.
• Surface / rubbing fastness can be weaker.

But simply extending time indefinitely is not an efficient control strategy.

The production target is the shortest stable residence time that gives the required:

• Rendement en couleur
• Fastness
• Shade
• Fabric quality

3. Temperature and Time Are Coupled, but Not Perfect Substitutes

A higher temperature can often achieve a similar or stronger fixation response in less time.

A lower temperature may require longer time.

Cependant :

Temperature × Time Is Not a Simple Interchangeable Number.

Different thermal conditions can change:

• Dye diffusion rate
• Dye sublimation / migration tendency
• Pretreatment-film behavior
• Polyester dimensional response

For example, published polyester inkjet research compared combinations including lower-temperature / longer-time and higher-temperature / shorter-time conditions, and the K/S response did not increase indefinitely with thermal severity.

Therefore, optimize a two-dimensional temperature–time window rather than one variable alone.

What Happens When Temperature Is Too Low?

Possible symptoms include:

• Low post-wash K/S
• Large amount of removable surface dye
• Weak dry / wet rubbing fastness
• Good pre-fixation appearance but poor final color

If the print is sharp before fixation but weak after reduction clearing, insufficient dye diffusion is a stronger suspect than pretreatment sharpness.

What Happens When Time Is Too Short?

A short thermal exposure can produce symptoms similar to low temperature:

• Incomplete dye diffusion
• Higher floating / removable dye
• Lower final color yield

Before increasing pretreatment polymer or ink load, verify whether the existing fixation time allows the selected disperse dye to reach its intended polyester depth.

What Happens When Thermal Severity Is Too High?

Excessive temperature or time can create different risks depending on dye, polymer, fabric and equipment.

Possible effects include:

• Unwanted dye migration
• Sublimation loss or shade instability for susceptible dyes
• Changes in surface-polymer film
• Fabric dimensional change
• Increased energy cost

One published direct-polyester inkjet study, for example, showed strong K/S at two high-temperature conditions but did not show continuous improvement at the highest tested thermal condition.

The important lesson is:

Do Not Optimize Thermofixation by Maximum Heat Exposure.

What Pretreatment Must Do Before Thermofixation

Before fixation, the pretreatment has already performed its main image-formation job.

It should have helped control:

• Lateral ink spreading
• Pénétration
• Printed-line width
• Surface color distribution

During thermofixation, that same pretreatment should not prevent an acceptable amount of disperse dye from moving into the polyester.

Therefore, a good direct-disperse pretreatment balances:

Pre-Fixation Surface Hold

with:

Thermal Dye Transfer into Polyester.

Pretreatment Polymer: Sharpness Before Fixation vs. Dye Release During Fixation

Polymeric pretreatments improve sharpness by restricting uncontrolled ink flow on the polyester surface.

But high polymer concentration or an overly continuous film can also retain more disperse dye near the surface.

Research on direct disperse inkjet systems has noted this trade-off: water-borne macromolecular pretreatments help prevent infiltration and improve sharpness, but they can also hinder dye penetration into polyester and increase floating color that must later be washed away.

The correct polymer add-on is therefore:

Enough to Control Spreading, but Not More Than Needed for the Required Surface Localization.

When Polymer Add-On Is Too Low

Before fixation, low polymer add-on can cause:

• Wider droplets
• Fuzzy edges
• Deeper uncontrolled penetration

Thermofixation cannot restore geometric sharpness that was already lost during printing.

If the image is blurred before fixation, changing fixation temperature is usually not the first correction.

When Polymer Add-On Is Too High

Excess polymer can create:

• Very strong surface localization
• Heavy dried film
• More retained surface dye
• Greater after-wash demand

The print may look dark and sharp before washing but lose significant color during reduction clearing if a large fraction of the dye never diffused effectively into PET.

This is why pre-wash K/S should not be used alone to approve pretreatment dosage.

Polymer Chemistry Changes the Thermal Response

Different pretreatment polymers do not behave identically when heated.

Possible differences include:

• Formation d'un film
• Softening behavior
• Rétention d'eau
• Dye affinity
• Thermal stability

Common pretreatment routes can use polysaccharides, cellulose derivatives or synthetic / compound polymers.

A thermofixation window validated for one polymer system should not automatically be transferred to another.

Pretreatment Rheology Still Matters During Fixation

Rheology acts mainly before fixation, but its effects continue into thermofixation because it determines:

• How much polymer remains on the face
• How deeply chemistry penetrates
• How uniformly the surface layer dries

Two pretreatments with the same standing viscosity can create different polymer distributions.

Those distributions can then release disperse dye differently during heat fixation.

Therefore:

Same Brookfield Viscosity ≠ Same Thermofixation Response.

Salts and Ionic Auxiliaries

Some published polyester inkjet pretreatments contain salts that alter polymer rheology or surface interaction.

Selected formulations have shown improvements in sharpness and color yield.

But salt effects depend on:

• Ion type
• Valence
• Polymer chemistry
• Posologie

Salt residue also remains present during thermofixation and after-treatment.

Do not copy one literature salt formulation as a universal polyester recipe.

Film-Forming / Crosslinkable Pretreatments

Some specialized polyester pretreatments contain latex, resin or crosslinkable chemistry.

For these systems, the fixation heat can perform two functions simultaneously:

• Promote disperse-dye diffusion into PET
• Change or cure the pretreatment film

Published one-bath polyester inkjet research has shown that pretreatment chemistry and curing temperature/time can interact strongly with final K/S and surface properties.

This is an important boundary:

A Thermofixation Window Can Also Be a Pretreatment-Film Reaction Window.

Therefore, supplier-specific instructions matter more for reactive / crosslinkable pretreatment systems.

Pretreatment Drying Is Not Thermofixation

Before printing, pretreatment is commonly dried to create a controlled surface.

This stage primarily removes the pretreatment carrier water and establishes polymer distribution.

It is not the stage where disperse dye is fixed, because no printed disperse dye is present yet.

Keep these settings separate in production records:

• Pretreatment drying temperature / time
• Thermofixation temperature / time

Confusing the two makes troubleshooting difficult.

Post-Print Drying Is Also a Separate Stage

Some direct disperse processes include drying or stabilization after inkjet printing but before final thermofixation.

Its purpose is to control the wet printed image and handling before high-temperature fixation.

If post-print drying is inadequate, ink can continue to move before thermofixation.

If it is excessively aggressive, the surface deposit can change before dye diffusion begins.

Record this stage independently when it exists.

Residual Moisture Before Thermofixation

The moisture state entering thermofixation affects the early heating phase.

More retained moisture means:

• More energy is initially used for water evaporation.
• The printed surface can remain mobile for longer.
• Actual fabric-temperature rise can lag the chamber setting.

This is why two fabrics exposed to the same nominal thermofixation condition can experience different thermal histories if their incoming moisture differs.

Keep pre-fixation moisture reasonably consistent during a temperature/time study.

Measure Sharpness Before and After Fixation

This is one of the fastest diagnostic tools.

Before Fixation	After Fixation	Likely Direction
Blurred	Blurred	Pretreatment / printing / wet-image control
Sharp	Less sharp	Thermal migration / fixation-stage movement
Sharp	Sharp but weak after washing	Insufficient dye diffusion / fixation
Sharp and dark before wash	Large color loss after clearing	High surface dye / incomplete fixation

Do not use final K/S alone to decide whether the defect began before or during thermofixation.

Thermal Migration During Fixation

When heat is applied, dye and residual formulation components gain mobility.

If the pretreatment surface contains too much unfixed dye or a film with strong dye affinity, heat can change where the dye resides.

Possible effects include:

• Edge softening
• Surface dye redistribution
• Reduced white-ground cleanliness

Thermal migration is dye- and system-specific.

If image geometry changes only after fixation, compare lower and higher thermal severity while keeping pretreatment and printing constant.

How Thermofixation Changes Color Yield

Color yield generally improves as more disperse dye enters and remains in the polyester within the useful fixation window.

Published direct-inkjet polyester work has shown large K/S differences among different temperature/time combinations.

But final K/S is a combined result of:

• Initial ink amount
• Pretreatment localization
• Dye diffusion
• After-treatment loss

Always compare post-wash / post-clearing K/S.

How Thermofixation Changes Dye Penetration

Before fixation, disperse dye can remain concentrated near the printable face.

During fixation, dye diffuses into PET.

Higher thermal severity can increase penetration into the fiber phase, but this is not the same as liquid ink penetration through the fabric thickness.

Distinguish:

• Liquid Penetration Before Fixation — controlled mainly by ink, pretreatment and fabric structure.
• Molecular Dye Diffusion During Fixation — controlled mainly by dye/PET thermal kinetics.

These mechanisms should not be confused.

How Thermofixation Changes Fastness

When more dye becomes incorporated into polyester rather than remaining as loose surface color, resistance to after-treatment and rubbing can improve.

But fastness also depends on:

• Dye chemistry
• After-treatment quality
• Residual surface dye
• Fabric / finish

Do not assume high K/S automatically means adequate fastness.

Both should be tested.

Why Reduction Clearing Matters to the Final Evaluation

Many direct disperse printing processes use reduction clearing or another validated wash-off route after heat fixation.

This removes:

• Unfixed / surface disperse dye
• Residual pretreatment polymer
• Other process residues

A thermofixation condition should therefore be approved from the fabric after the normal clearing / washing sequence.

Otherwise, surface dye can make an under-fixed condition appear darker than it really is.

Different Disperse Dyes Need Different Thermal Windows

Disperse dyes differ in:

• Molecular size
• Energy class
• Sublimation fastness
• Diffusion behavior
• Thermal stability

A thermofixation condition developed for one red dye is not automatically correct for:

• Another red
• Blue
• Black mixture
• A different ink supplier

Multi-color production should be validated with the most demanding shade / ink set, not only one convenient laboratory color.

Polyester Construction Changes the Thermofixation Window

Fabric construction changes heat transfer and dye distribution.

Important variables include:

• GSM
• Thickness
• Filament count
• Porosity
• Étirement

Therefore, a fixation setting should be validated on the real production fabric rather than on polyester fiber identity alone.

Woven Polyester

Stable woven fabrics can show relatively predictable residence and dimensional behavior.

But dense woven construction can require different heat penetration from lightweight open weave.

Vérifier :

• Face / back shade
• Dimensional change
• Post-clearing K/S

Knitted Polyester

Knits can respond strongly to heat and tension.

Thermofixation can interact with:

• Réglage de la largeur
• Relaxation
• Étirement
• GSM

Record fabric dimensions together with color results during scale-up.

Microfiber Polyester

Fine-filament polyester has high surface area and can display different dye uptake and thermal response from conventional filament fabric.

Do not transfer a coarse-filament thermofixation window directly to microfiber without testing.

Polyester Blends

Polyester blends can impose additional thermal constraints because the second fiber or finish may respond differently to high temperature.

For blends, check:

• Thermal tolerance of all fiber components
• Stabilité dimensionnelle
• Shade on the polyester component
• Hand

Do not optimize fixation solely for PET if the complete fabric cannot tolerate the condition.

Production Thermofixation Equipment

Laboratory hot-air devices and production stenters / fixation units do not create identical thermal histories.

Production adds:

• Full-width airflow
• Continuous fabric motion
• Zone-to-zone temperature profiles
• Exhaust and chamber humidity
• Tension du tissu

Scale-up should therefore reproduce:

• Final post-clearing K/S
• Netteté
• Fastness
• Fabric dimensions

rather than simply copying the laboratory set temperature.

Set Temperature vs. Actual Fabric Temperature

The machine setpoint is not always the fabric temperature.

Actual fabric heating depends on:

• Incoming moisture
• Fabric mass
• Air velocity
• Temps de séjour
• Machine loading

During the early part of the fixation zone, evaporation and heat transfer can delay the fabric reaching the target thermal condition.

Use direct or validated indirect fabric-temperature measurements when precise scale-up is required.

Nominal Residence Time

Where effective fabric path length is known:

Nominal Residence Time = Effective Heated Path Length ÷ Line Speed

This provides a useful production reference.

But:

Same Nominal Residence Time ≠ Same Thermal Exposure.

Airflow and actual fabric temperature must also be considered.

Airflow and Widthwise Thermal Uniformity

Uneven airflow can create different thermal histories across the fabric width.

This can produce:

• Left-to-right K/S variation
• Different dye diffusion
• Different dimensional response

If pretreatment and printing are uniform before fixation but post-fixation shade becomes uneven, map:

• Airflow
• Température du tissu
• Post-clearing K/S

across the width.

Build a Temperature × Time Matrix

Start from the ink supplier / validated process baseline.

Then build a controlled matrix around it.

Condition	Température	Time	Post-Clearing K/S	Fastness / Shade
A	Lower controlled	Longer	Measure	Evaluate
B	Reference	Reference	Contrôle	Contrôle
C	Higher controlled	Shorter	Measure	Evaluate
D	Reference	Shorter	Measure	Under-fix stress point
E	Higher controlled	Reference	Measure	Thermal stress point

The exact temperatures and times must come from the selected disperse ink, polyester substrate and equipment.

Do not copy literature conditions as production defaults.

Build a Pretreatment × Thermofixation Matrix

After the basic temperature/time window is known, compare pretreatment levels.

Pretreatment Condition	Lower Thermal Severity	Reference Thermal Severity	Higher Thermal Severity
Lower polymer add-on	Test	Test	Diagnostic
Reference add-on	Test	Contrôle	Test
Higher polymer add-on	Diagnostic	Test	Test

For each condition, compare:

• Pre-fixation sharpness
• Post-fixation sharpness
• Post-clearing K/S
• Fastness
• Tissu à la main

This identifies whether a fixation problem is being masked by excess or insufficient pretreatment.

Recommended Diagnostic Sequence

1. Confirm print sharpness before thermofixation.
2. Freeze pretreatment, ink load and printer settings.
3. Run a temperature × time matrix.
4. Measure post-clearing K/S and fastness.
5. Check whether image geometry changes during fixation.
6. If fixation remains weak, inspect polymer add-on / surface dye retention.
7. Only then change pretreatment chemistry.

This prevents the mill from trying to solve an under-fixation problem by increasing thickener or ink load.

Recommended Laboratory Workflow

1. Use one representative polyester fabric lot.
2. Freeze pretreatment product, add-on and pretreatment drying.
3. Freeze disperse ink, printer mode and ink coverage.
4. Measure sharpness before fixation.
5. Apply the reference thermofixation condition.
6. Build controlled lower / reference / higher temperature-time conditions around the validated baseline.
7. Use the same post-fixation reduction clearing / washing route.
8. Measure post-clearing K/S.
9. Measure sharpness again.
10. Evaluate rubbing / washing fastness as required.
11. Check dimensional change and fabric hand.
12. Select a robust temperature–time window rather than one narrow optimum.

For controlled process matching, use Échantillons et correspondances.

Production Trial Approval

Record:

• Polyester construction / GSM / width
• Disperse ink supplier / grade
• Pretreatment product / batch
• Pretreatment concentration / dry add-on
• Pretreatment drying conditions
• Residual moisture before printing
• Print mode / ink load
• Post-print drying if used
• Thermofixation equipment
• Zone / set temperatures
• Line speed / residence time
• Actual fabric temperature where available
• Widthwise uniformity
• Reduction clearing / washing
• Post-clearing K/S
• Netteté
• Fastness
• Fabric dimensions / hand

Approve the combined pretreatment–printing–thermofixation process rather than one temperature number.

Common Thermofixation Mistakes

1. Treating Higher Temperature as Automatically Better

Higher temperature accelerates dye diffusion but can also change migration, shade, pretreatment film and fabric dimensions.

2. Changing Pretreatment and Fixation at the Same Time

The source of the final K/S or sharpness change becomes unclear.

3. Evaluating Color Before Reduction Clearing

Surface dye can make an under-fixed condition look deceptively strong.

4. Using One Universal Temperature / Time for All Disperse Inks

Dye molecular structure and sublimation behavior differ.

5. Ignoring Pretreatment Polymer Add-On

Too much surface polymer can limit dye transfer into PET and increase floating color.

6. Confusing Liquid Penetration with Molecular Dye Diffusion

One occurs mainly before fixation; the other occurs during thermal fixation.

7. Copying Laboratory Temperature Directly to Production

Actual fabric temperature and airflow can differ substantially.

8. Approving the Average Shade but Ignoring Widthwise Variation

Uneven airflow can create different fixation across the fabric width.

Troubleshooting Table

Problème constaté	First Variables to Check	Do Not Assume
Sharp before fixation, weak after clearing	Temperature, time, polymer surface retention, dye class	More pretreatment is the first solution
Blurred before fixation	Pretreatment add-on, ink spreading, residual moisture	Thermofixation can restore sharpness
Sharp before fixation, blurrier after fixation	Thermal migration, temperature severity, pretreatment film	The printer caused the final blur
High pre-wash K/S but large color loss after clearing	Surface dye, fixation depth, excess polymer	Pre-wash color proves good fixation
K/S increases with temperature then plateaus / falls	Dye-specific optimum, sublimation / migration, time	Continue increasing temperature
Production shade differs left-to-right	Airflow, actual fabric temperature, residence uniformity	Pretreatment concentration is globally wrong
Different ink color fixes differently	Dye class / molecular structure, ink supplier guidance	One temperature-time pair fits every color
Good K/S but poor rubbing fastness	Surface dye, after-treatment, fixation depth	High color strength guarantees good fastness

Coût total d'utilisation

Thermofixation affects:

• Energy
• Vitesse de la ligne
• Rendement en couleur
• Reduction-clearing load
• Rework

A useful model is:

Total Cost in Use = Pretreatment + Printing + Post-Print Drying + Thermofixation Energy + Reduction Clearing + Rework + Quality Loss

An overly severe fixation process can increase energy without improving post-clearing color.

An under-fixed process can save short-term energy but increase:

• Surface dye
• Clearing demand
• Rework
• Fastness failures

Optimize cost per acceptable finished meter.

What Information Should You Send to a Supplier?

For useful thermofixation / pretreatment troubleshooting, provide:

• Polyester fabric construction / GSM
• Direct disperse ink supplier / grade
• Current pretreatment product / TDS
• Pretreatment concentration / dry add-on
• Pretreatment application route
• Pretreatment drying conditions
• Residual moisture if available
• Printer / print mode / approximate ink coverage
• Post-print drying if used
• Thermofixation equipment
• Set temperature(s)
• Line speed / residence time
• Reduction clearing / washing conditions
• Pre-fixation sharpness
• Post-fixation / post-clearing K/S and sharpness
• Main issue: low color, thermal blur, migration, floating dye or fastness

FSX Chemical can use this information through Échantillons et correspondances to separate pretreatment and thermal-fixation causes.

Critique Digital Textile Printing Pretreatment, Textile Printing Thickener Testing Parameters et Textile Printing Applications for related process control.

How Should a Mill Optimize Thermofixation for Direct Disperse Inkjet Printing?

A practical workflow is:

Freeze Pretreatment → Confirm Pre-Fixation Sharpness → Build Temperature × Time Matrix → Fix → Reduction Clear / Wash → Measure K/S / Sharpness / Fastness → Check Fabric Dimensions → Then Fine-Tune Pretreatment If Needed

Les principes fondamentaux sont les suivants :

1. Temperature accelerates disperse-dye diffusion into polyester, while time controls how long that diffusion can proceed.
2. Temperature and time interact but are not perfectly interchangeable because they also affect dye migration, pretreatment films and fabric behavior.
3. Pretreatment must provide enough surface hold for sharp printing without trapping excessive dye outside the polyester during fixation.
4. Pretreatment drying, post-print drying and thermofixation are three separate process stages and should be recorded separately.
5. Pre-fixation sharpness and post-clearing K/S should both be measured so image-formation defects can be separated from fixation defects.
6. The best process is the temperature–time–pretreatment window that gives stable post-clearing color, sharpness, fastness and fabric quality at the lowest practical Total Cost in Use.

Foire aux questions

1. What is thermofixation in direct disperse inkjet printing?

It is the high-temperature stage used to promote molecular diffusion of disperse dye from the printed textile surface into polyester after direct inkjet printing.

2. Is a higher thermofixation temperature always better?

No. Higher temperature can accelerate dye diffusion, but excessive thermal severity can increase migration, sublimation risk, energy use or fabric / pretreatment-film changes.

3. Can lower temperature be compensated by longer time?

Sometimes partially, but temperature and time are not perfectly interchangeable. Dye class, PET structure and pretreatment chemistry must be considered.

4. Why does the print look dark before washing but become weak after reduction clearing?

A large fraction of the dye may still be on or near the surface rather than effectively diffused into polyester. Check fixation temperature/time and pretreatment polymer add-on.

5. Can too much pretreatment thickener reduce fixation?

It can in some systems. Excess polymer may retain more dye in the surface film and increase floating color, even while improving pre-fixation sharpness.

6. Is pretreatment drying the same as thermofixation?

No. Pretreatment drying occurs before printing and establishes the pretreatment surface. Thermofixation occurs after printing and promotes disperse-dye diffusion into polyester.

7. Is post-print drying the same as thermofixation?

No. Post-print drying or stabilization controls the wet printed image before the high-temperature dye-fixation stage.

8. Why can sharpness become worse after thermofixation?

Thermal migration, excessive thermal severity, surface-film behavior or residual dye mobility can change edge definition during fixation.

9. What should be measured besides K/S?

Measure pre- and post-fixation sharpness, post-clearing K/S, penetration, rubbing/washing fastness, white-ground cleanliness and fabric dimensions as relevant.

10. Can one thermofixation recipe be used for every disperse ink color?

Not automatically. Different disperse dyes and ink formulations can have different molecular size, diffusion and sublimation behavior.

11. Why can production fixation differ from the laboratory?

Actual fabric temperature, airflow, moisture, line speed and residence uniformity can differ even when the nominal temperature is similar.

12. What should I send FSX Chemical for thermofixation troubleshooting?

Send the polyester construction, disperse ink/TDS, pretreatment/TDS and add-on, drying conditions, thermofixation temperature/time or line speed, reduction clearing route and pre-/post-fixation print results.

Match Pretreatment Surface Control with the Thermofixation Window

If direct disperse printing on polyester is sharp before fixation but loses color, develops thermal blur, shows high floating dye or changes fastness after thermofixation, FSX Chemical can help separate pretreatment, dye-diffusion and production-heating causes.

Commencez par Échantillons et correspondances and provide your current polyester, disperse ink, pretreatment and thermofixation conditions.

Critique Digital Textile Printing Pretreatment for current FSX pretreatment routes📧 E-mail: Service@fsxchemical.com

The correct thermofixation condition is not the highest temperature or longest time. It is the controlled thermal window that releases enough disperse dye from the printed pretreatment layer, drives it into polyester efficiently, preserves image geometry and fabric quality, and minimizes removable surface dye after the normal clearing process.