The three most common problems
- Poor adhesion
- Colour (dye) Migration
- Cutting or Weeding issues.
1) Problems with Adhesion
First - Is the product suitable for use with a heat transfer? Some products have waterproof or water resistant coatings that prevent the adhesive from bonding well or bonding at all.
How can you tell of a fabric has a water-resistant finish or coating?
Use an eye dropper and place one drop of water onto the surface of the fabric. The different levels of water resistance can be seen by the way the water droplet is either absorbed or repelled. (See images below)
Second - is your heat press up-to-the-job?
- Does it produce the correct temperature? If it is not a good quality press or if it has not been calibrated well, the actual temperature inside the press might be different to the temperature shown on the display. Also please remember that most heat presses do not reach full temperature clo9se to the edges.
- Does your press produce even pressure across the full width of the bed? Some beds become curved after extensive use and the silicone rubber pads can also become uneven.
- Are you pressing the heat transfer at the right temperature, pressure and time as per the transfer manufacturer's recommendations?
- Has the heat press reached the set temperature and have you operated the press once or twice to make sure that the bottom platen is hot before you press a logo. If you don't do this then the first one or two logos might not adhere fully.
Third - Are you using the right kind or heat transfer?
Some products that have a light water resistant coating can be decorated with heat transfer but you musty use a different transfer type which is usually called Extra or heavy-duty. It has a thicker layer of adhesive hat is designed to penetrate more deeply into the fibers for stronger bond.
Fourth - Is the heat transfer being used for cold-peel or for hot-peel. A cold peel film must be allowed to cool down first before peeling the carrier.
Final Adhesion:
- If a heat transfer appears to be fully adhered to the garment but then shows signs of peeling after laundering then the most likely cause is an issue with layering or laundering. It is very important to always use the same kinds of peel films for layered heat transfers; that is warm peels on warm peels and cold peels on cold peels. When it comes to metallic peels, the metallic peel should always be on top.
- Another important thing to check is that you're applying to right film to the fabric you're working with. Films that work very well on nylon and leather may cause issues on cotton, polyester and blended garments.
- The other likely cause of final adhesion issues is issues with laundering. This problem can be very difficult to identify because you can't control how end-users launder garments and from experience the end users are not likely to confess that maybe they made a mistake.
- Some work-wear gets very dirty. End users might use harsh laundry detergents and hot water neither of which are good.
- Bleach is always a "No"
- Fabric softeners also should not be used
- Drying machines can produce temperatures that are too high for many heat transfers. This can affect not only the adhesive but the film too. If a customer complains that the transfer is wrinkly and/or misshapen after laundering then it is almost certainly because it has been through a dryer and was left crumpled whilst it was cooling down.
- Cotton garments like T shirts often shrink a little after the first wash. This will cause the heat transfer to take on a wrinkly appearance because the fabric that it is adhered to has shrunk. The solution: Pre-wash and dry the garments before applying the heat transfer or try heat pressing the logo again to see of the wrinkled appearance will reduce.
Color Migration
Colour migration is what happens mostly with polyester garments that have been dyed with strong colours like Red, Black, Navy Etc. The dyes use are called sublimation dyes and they are activated by heat. Some of the dye migrates into the heat transfer during laundering, drying or ironing. Oddly enough it is not always apparent at the time of heat pressing but can happen slowly over time.
Not only can the heat transfer be affected by dye migration but with some garments there can be a transfer of colour from the fabric into the transfer film too. This would typically show up as a square or rectangular area around the logo that is a little lighter in colour as compared to the rest of the garment.
For example, white graphics applied to dark polyester or cotton shirts might become grey instead. There are 3 ways to deal with this:
What can be done to avoid these problems?
- Use dye sublimation blocking film can help to prevent the dye from being absorbed into the heat transfer. Note: Dye sub blocking films tend to be thicker than regular heat transfer and so might not have a soft feel.
- Reducing the temperature of the heat press to a level that is not enough to activate the dye. Note: The heat transfer adhesive must be of a type that will melt at a lower temperature (130 deg C or less)
Cutting Problems
For the most part, heat transfer film is very simple to cut, as it is very thin and soft. Problems that can arise are probably a result of 1 of 4 things; incorrect blade, an extra liner, improper film loading or excessive blade wear.
- Incorrect Blade. The thickness and density of a fabric determines which kind of blade you'll need to cut it. For most regularly garments, a standard issue 45° plotter blade is sufficient. For thicker and denser garments and fabrics, a 60° blade known as a "flock blade" will be necessary. There is also a special blade made specifically for cutting fine details like small characters.
- Extra liners. In order to protect some of the more specialised films like reflective film, there might be a liner covering the face film. This layer is purely for protection during transportation and storage, and will interfere with cutting if it's left on. Carefully remove the extra liner in an area only large enough to cut the image and nothing more before you begin cutting.
- Is the film loaded into the cutter with the right side facing upwards? Cut-only films are cut from the reverse side (adhesive side up / coloured side down) with logo in regular view. Printable films are printed and cut right side up with logos mirrored.
- Blade adjustment and wear. If everything else is looking good; you're using the correct blade, the extra liner layers are removed, and the film is loaded properly, it may simple be the case that your blade has been blunted or worn down through extended use.
- Use correct blade type
- If in doubt - try a new blade.
- Check for correct blade depth (approx. 1 credit card thickness protruding from the blade holder)
- Check for correct blade pressure and cut speed
- TEST BEFORE STARTING PRODUCTION
Weeding Problems.
The most likely cause of a weeding problem is that you've cut into or through the face film, but haven't cut through the adhesive. Alternatively, you may have cut too deeply, which can occur when using a film on a paper liner. The best way to avoid either of these problems is to make sure you do a test cut. If the test cut comes out fine after weeding, only then should you send the job through.
If the blade depth and pressure are adjusted well you should be able to see a light score mark on the liner film after the transfer has been applied. If the liner is deeply scored, you've used too much force and/or cut too deep. If the liner isn't scored at all, you haven't cut all the way through the adhesive, which means you have cut too lightly and/or used too little force.
