Check the mixture quality and process conditions first.
Product and application
Select the system so that only relevant test steps appear. If no system is specified, the test will remain general.
01
What are you observing?
02
Identify the cause
03
For reference
All test steps in this guide can be used even without the guided process.
Terms briefly explained
Hand strength
The parts should be handled carefully. The connection is not yet fully load-bearing.
Complete curing
The curing conditions and times prescribed for the product were adhered to.
Adhesive gap
Distance between the two joining surfaces, not the length of the adhesive seam.
Pot life and nozzle life
Test the processability of a mixed quantity and the processability in the mixing nozzle separately.
Remains soft or hardens too slowly: 3 test steps
Test unmixed areas, cold temperatures, and aged material separately.
1 · Mixture
Do the components, mixing ratio and mixing nozzle match the product data sheet?
Uneven application or unsuitable nozzles will leave unmixed areas. A general mixing ratio does not apply to all products.
Check the correct resin/hardener combination and prescribed ratio.
Check the cartridge piston, the discharge of both components, and the recommended mixing nozzle; pre-run the nozzle according to the manufacturer's instructions.
For dosing systems, check the actual quantities of both components. Document any streaks or unmixed areas.
2 · Temperature
Does the actual processing temperature correspond to the specifications for the product?
Cold temperatures slow down many curing reactions. A thin layer of adhesive may cure more slowly than a larger, mixed quantity.
Measure the temperature of the material, component, and workplace.
Adhere to the specified waiting and curing times. Use heat only within the product-specific curing plan.
Consider pot life and time in the mixing nozzle separately from the time until load-bearing capacity.
3 · Storage
Has the material been stored within its shelf life and according to the data sheet?
Aging, humidity, separation of components or unsuitable temperatures can alter processing and hardening.
Record batch number, expiry date and inventory history.
Check for segregation, thickening, and contamination. Do not correct conspicuous material with unauthorized additives.
If the material quality is unclear, check a fresh, correctly stored batch for comparison.
Air bubbles: 3 test steps
Air can be introduced during transfer and mixing.
1 · Air entry
Is the material processed with as little air as possible during transfer and mixing?
Stirring, spatula use, and open transfer can trap air.
Mix slowly and in a controlled manner, without incorporating air.
Check suitable immersion tubes or follower plates for large containers.
2 · Ventilation
Is a suitable vent provided for the product?
Tough materials often release trapped air only slowly.
Test for suitability using vacuum degassing or vibration.
Only apply additional heat within the permissible process window.
3 · Mixture
Do the components, mixing ratio and mixing nozzle match the product data sheet?
Uneven application or unsuitable nozzles will leave unmixed areas. A general mixing ratio does not apply to all products.
Check the correct resin/hardener combination and prescribed ratio.
Check the cartridge piston, the discharge of both components, and the recommended mixing nozzle; pre-run the nozzle according to the manufacturer's instructions.
For dosing systems, check the actual quantities of both components. Document any streaks or unmixed areas.
Viscosity changes: 2 test steps
Aging and thixotropic behavior can alter the flow.
1 · Storage
Has the material been stored within its shelf life and according to the data sheet?
Aging, humidity, separation of components or unsuitable temperatures can alter processing and hardening.
Record batch number, expiry date and inventory history.
Check for segregation, thickening, and contamination. Do not correct conspicuous material with unauthorized additives.
If the material quality is unclear, check a fresh, correctly stored batch for comparison.
2. Homogeneity
Is the material homogeneous and without separation of components?
Stirring can temporarily reduce the viscosity of thixotropic products.
Check for segregation and homogenize only according to product specifications.
Avoid incorporating air while stirring; recheck dosage and flow behavior.
Lumps or crystals: 2 testing steps
Crystallization and cross-contamination are different causes.
1. Cross-contamination
Do the resin and hardener outlets remain cleanly separated?
Residue at the cartridge outlet can mix components during nozzle changes.
Check outlets and nozzle changes.
Document batch, storage conditions, and photos. Handle crystals only according to the manufacturer's product-specific procedure.
2 · Storage
Has the material been stored within its shelf life and according to the data sheet?
Aging, humidity, separation of components or unsuitable temperatures can alter processing and hardening.
Record batch number, expiry date and inventory history.
Check for segregation, thickening, and contamination. Do not correct conspicuous material with unauthorized additives.
If the material quality is unclear, check a fresh, correctly stored batch for comparison.
Stress cracks in plastic: 3 test steps
Uncured material and poor mixing can damage sensitive plastics.
1 · Mixture
Do the components, mixing ratio and mixing nozzle match the product data sheet?
Uneven application or unsuitable nozzles will leave unmixed areas. A general mixing ratio does not apply to all products.
Check the correct resin/hardener combination and prescribed ratio.
Check the cartridge piston, the discharge of both components, and the recommended mixing nozzle; pre-run the nozzle according to the manufacturer's instructions.
For dosing systems, check the actual quantities of both components. Document any streaks or unmixed areas.
2 · Response time
Is the exposure time of uncured material sufficiently short?
Faster hardening can shorten the exposure time.
Check the faster-curing type or suitable mixing nozzle with the application technology.
Test compatibility on the specific plastic.
3 · Surface
Are the actual materials clean, dry, and properly prepared?
Oil, release agents, varnishes, and weak oxide layers can impair adhesion. Changing suppliers can also alter the surface.
Determine the material and alloy or plastic mixture. Ask the supplier about any changes to release agents, plasticizers, and coatings.
Adjust the cleaning process to the material and allow the cleaning agent to evaporate completely. Check the blasting media for cleanliness and condition.
Apply adhesive promptly after pretreatment and avoid further contact or oxidation. If necessary, test wettability using suitable testing methods.
Insufficient strength: 3 test steps
First, define the fracture pattern and then examine the surface, application, and load.
1 · Surface
Are the actual materials clean, dry, and properly prepared?
Oil, release agents, varnishes, and weak oxide layers can impair adhesion. Changing suppliers can also alter the surface.
Determine the material and alloy or plastic mixture. Ask the supplier about any changes to release agents, plasticizers, and coatings.
Adjust the cleaning process to the material and allow the cleaning agent to evaporate completely. Check the blasting media for cleanliness and condition.
Apply adhesive promptly after pretreatment and avoid further contact or oxidation. If necessary, test wettability using suitable testing methods.
2 · Order & Fixing
Is sufficient adhesive applied to the correct area and is the joint held still during the curing process?
Gaps in the order, incorrect contact points, and movements during curing can explain local failures.
Check the dosage and actual wetting of the contact surface.
Maintain fixation until the required strength is achieved; pay attention to air gaps and torn structures.
Document the error rate and distribution. Individual failures may indicate fluctuating process conditions.
3 · Load
Is the bond only subjected to stress within its operating conditions after sufficient curing?
Premature stress, peeling forces, media, or differing thermal expansion can weaken a connection that initially appears to be good.
Compare the waiting time before loading with the product data sheet.
Capture joint geometry, temperature, chemicals and humidity in real-world use.
For peeling loads or different materials, test tougher or more flexible systems with the application engineer.
No or uneven discharge: 3 test steps
Check the cartridge, mixing nozzle, and material condition separately.
1 · Exit
Do both components dispense evenly from the designated cartridge?
Uneven application can alter the mixing ratio.
Check the dispensing gun, piston position and outlets according to the product specifications.
Avoid cross-contamination. Do not correct hardened or conspicuous material with additives.
2 · Mixture
Do the components, mixing ratio and mixing nozzle match the product data sheet?
Uneven application or unsuitable nozzles will leave unmixed areas. A general mixing ratio does not apply to all products.
Check the correct resin/hardener combination and prescribed ratio.
Check the cartridge piston, the discharge of both components, and the recommended mixing nozzle; pre-run the nozzle according to the manufacturer's instructions.
For dosing systems, check the actual quantities of both components. Document any streaks or unmixed areas.
3 · Storage
Has the material been stored within its shelf life and according to the data sheet?
Aging, humidity, separation of components or unsuitable temperatures can alter processing and hardening.
Record batch number, expiry date and inventory history.
Check for segregation, thickening, and contamination. Do not correct conspicuous material with unauthorized additives.
If the material quality is unclear, check a fresh, correctly stored batch for comparison.
Mixing nozzle gels too quickly - 3 test steps
Standing time and temperature can limit processing in the nozzle.
1 · Nozzle life
Is the permissible service life in the mixing nozzle being observed?
Pot life, nozzle life, and time until load-bearing capacity are different specifications.
Log downtime and actual material temperature.
Replace the mixing nozzle according to the manufacturer's instructions. Do not use a shorter nozzle without proof of suitability.
2 · Temperature
Does the actual processing temperature correspond to the specifications for the product?
Cold temperatures slow down many curing reactions. A thin layer of adhesive may cure more slowly than a larger, mixed quantity.
Measure the temperature of the material, component, and workplace.
Adhere to the specified waiting and curing times. Use heat only within the product-specific curing plan.
Consider pot life and time in the mixing nozzle separately from the time until load-bearing capacity.
3 · Mixture
Do the components, mixing ratio and mixing nozzle match the product data sheet?
Uneven application or unsuitable nozzles will leave unmixed areas. A general mixing ratio does not apply to all products.
Check the correct resin/hardener combination and prescribed ratio.
Check the cartridge piston, the discharge of both components, and the recommended mixing nozzle; pre-run the nozzle according to the manufacturer's instructions.
For dosing systems, check the actual quantities of both components. Document any streaks or unmixed areas.
German version prepared according to the archived Permabond guide troubleshooting-2-part-epoxyes.md. Always compare product-specific values and procedures with the corresponding technical data sheet.
