Hot Peel/Hot Split Transfers
“Hot peel” or “hot split” refers to transfers made by peeling away the transfer paper immediately after they are applied in the transfer press – or while they are still hot. Both hot peel and hot split are often used interchangeably, but they aren’t always the same. Hot split transfers split the ink film between the paper and the fabric after heat and pressure are applied. As the paper is peeled from the fabric, some of the ink remains on the transfer paper while the majority melts into the fabric. This splitting of the ink film produces a very soft, breathable print when using standard opacity inks. Some types of transfer inks melt almost entirely into the fabric and leave very little, if any, residual ink on the paper. The paper and/or the ink used, along with application time, temperature and pressure of the heat seal machine, all govern whether the ink melts entirely into the fabric or not. Hot peel transfers that release almost the entire ink film may not be quite as soft and breathable as hot split transfers. SoftTrans (ST-88) is a popular hot peel transfer paper designed to be used with hot split plastisol inks. It combines good dimensional stability with a special sizing designed to provide an even, consistent split for hot peel inks. This special sizing also helps to increase the shelf life of the printed transfer. Either side of the Soft Trans paper can be printed with good results.
Over gelation of the inks, when printing transfers, can cause poor release, spotty transfers, or poor adhesion. To print transfers, inks must be gelled between each color. Gelation temperatures usually range from 225°F to 275°F depending on ink film thickness, and the type of ink being used. Properly gelled ink is dry to the touch and should break apart easily if removed from the paper.
Hot split or hot peel inks are plastisol inks that have a lower melt point than standard plastisol inks. The lower melt point allows the inks to release or split quickly from the paper and to penetrate into the garment. This gives the inks a very soft hand and excellent durability. There are Hot Split Additives (like International Coatings Quick Trans 500 or Excalibur 906 Hot Split Additive) which can be added to standard plastisol inks to convert them to hot split or hot peel transfer inks.
Cold Peel Transfers
A cold peel transfer will deposit all of the ink onto the garment. These transfers usually have a thicker rubbery feel. Cold peel transfers have great opacity, but often must be used with adhesive powders sprinkled over the plastisol to achieve greater adhesion and durability. The most common cold peel paper (Transfer T-75) was developed to be smoother and more stable than parchment type paper. Parchment paper can be used, but is best suited for one-color transfers only… since it shrinks considerably when heated. T-75 is an ideal choice for multi-color jobs where registration and fine detail are important. However, it is for cold peel transfers only, and not recommended for hot split plastisol transfers. The gelation temperature for cold peel inks is usually around 180°F to 225°F. Poor adhesion and/or elongation (stretch) may result from over gelation of the inks. Adhesive powders can be sprinkled on wet ink and gelled for better adhesion and durability.
1. Never allow the paper to sit where it will be affected by weather conditions or possible damage.
2. Always stack cartons flat. Never stand on end side as this will cause curling and damage.
3. A cool dry, place is ideal for storing any type of heat transfer paper. Keep paper on racks or pallets away from excessive heat/moisture.
4. Always keep paper in original wrappers and cartons until the transfer paper is ready for use. Never leave unwrapped. Re-wrap or cover with plastic.
5. Rotate your paper stock often. Use first-in/first-out principle when managing your stock.
6. For the best transferring results, pre-shrinking the transfer paper is recommended for all multi-color jobs. Pre-shrinking of the paper should be done using the exact same conditions used for the print job (temperature and time on the dryer) and if possible, the same dryer as well. Immediately after pre-shrinking, the transfer paper must be covered with moisture proof paper or plastic, as humidity can cause paper to grow back to its original size within 10 minutes. Ideally, any type of pre-shrunk paper should be kept in a hot room or hot box at 90°F or above and should have low humidity.
7. For best color registration, the transfer paper should be exposed to the atmosphere as little as possible to prevent weathering and warping of the paper. Some printers have a mini hot box at the printing press or they use very small lifts with one person designated to bring the paper from the hot room to the printing press. This is extremely important on days where the weather has very high humidity levels.
8. In general, it is best to gel the plastisol ink at as low of a temperature as possible to prevent any kind of over gelation.
9. For printing jobs that use multiple colors, be sure to use long grain transfer paper whenever possible, as this will reduce the amount of shrinkage experienced with the transfer paper being used.