Sorry to hear that you are having a problem. If you have adequate heat to activate the adhesive & your time & pressure are good the following below may be your problem. What is the manufacture of the garment?
We have found that some polyester is giving us quite the challenge today. It is my understanding that sometimes a antimicrobial solution or SPF is being added to some of these fabrics. These chemicals are keeping the adhesives from bonding to the substrate. I even tested some other competitor’s products & had the same results so I’m confident it's something in the substrate.
We are also recommended that the customer TEST these products prior to a production run.
Lycra is a synthetic fiber most commonly added to cotton or polyester.
Screen printers are faced with these same challenges today.
A few ways we found to get around this was to wash the garment prior to heat application or apply methyl chloride to the area that you will be applying the vinyl. This chemical is readily available through screen printing supply companies. I have heard it called TS-3. The screen printers use it in a spray gun to blow out their screens. You could also out it in a plastic spray
bottle if you don’t have a spray gun.
This chemical is also used to dissolve our adhesive on the CUTTABLE vinyls if someone makes a mistake. I suggest that you apply it with a plastic syringe. The chemical is expensive & this helps to only apply it to the area where it's needed. Is doesn't seem to have an affect on the rubber or plastic parts of the syringe. I would not recommend that they store the solution in the syringe.
This would be applied to the inside of the garment so the solution is being introduced on the adhesive side of the vinyl. After applying the solution simply wait a few seconds for the adhesive to dissolve. Next, stretch the garment if the area where you wish to remove the vinyl. The vinyl will lift off the garment. You can then use a cotton cloth with a small saturation of the methyl chloride to remove an adhesive residue. This is not recommended for the print & cut materials as the inks will run rampant creating quite the mess. I have tried it all.
Migration is the other challenge that we are faced with today with polyesters. High heat is the main culprit. To combat this, simply reduce the application temperature & increase the dwell (application) time.
An example when applying EasyWeed -
Application Temp = normal temp is 305 degrees Fahrenheit - reduce this to 280 – 28 5degrees Fahrenheit
Application Time = normal 10 - 15 seconds - increase this to 15 - 20 seconds
Please feel free to call me if you need more assistance. Kathleen 440-665-5576